5.1 Summary. Summary & Conclusions

Transcription

1 5.1 Summary The thesis can be summarized as follows: 1. Introduction- It is the first chapter of the thesis. It describes about the importance of generic products, its role in pharmaco-economics of India. It also describes the rational behind selecting the study drug molecules. 2. Research envisaged and plan of work- this is the second chapter of thesis describes plan of work and rational behind the work. 3. Introduction to Experimental- This is the third chapter of the thesis describes the general procedure used for the method development, validation and study sample analysis of drug products. 4. Literature Survey, Experimental, Results and Discussion- This is the fourth chapter of the thesis and is divided into four sections. Each section describes the information found in the literature for the respective molecule, the experimental part and its results. The chapter also describes the statistical evaluation of the data. 4.1 Nevirapine - This is the first section of the chapter 4. HPLC - UV method for the analysis of nevirapine was developed and validated. The method was further applied for the sample analysis of bioequivalence study. 4.2 Efavirenz - This is the second section of the chapter 4. Two approaches of incurred sample reanalysis and its comparative evaluation- A traditional wet plasma analysis method was developed for the analysis of efavirenz on LC-MS/MS and validated. The method was further applied for the study sample analysis of bioequivalence study. Incurred sample reanalysis was performed on study samples by two approaches. An alternative method-dried Matrix Spot analysis- Dried matrix spot analysis method was developed on LC-MS/MS and validated. Study samples of one bioequivalence study were analyzed by traditional method and dried matrix spot analysis method. The comparison of the two methods was performed using student s t test and by regression analysis with Pearson s correlation. 4.3 Emtricitabine - This is the third section of the chapter 4. Plasma-urine correlation- A method for the analysis of emtricitabine was developed on LC-MS/MS and validated. The method was further applied for the study sample analysis of bioequivalence study. An alternative method from urine was developed for the estimation of emtricitabine and Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, Mumbai 304

2 validated. The urine samples were collected during bioequivalence study. Correlation between plasma and urine concentration was evaluated. 4.4 Terizidone - This is the fourth section of the chapter 4. A difficult molecule for bioanalysis. First time reporting of bioequivalence of terizidone by chromatographic method. LC-MS/SMS method for the analysis of cycloserine (metabolite of terizidone) was developed and validated. The method was further applied for the study sample analysis of bioequivalence study. 5. Summary and Conclusion-This chapter give brief summary of the entire thesis and final conclusion drawn from the research work. 6. Appendix-this includes the scanned copy of the related documents, used in the study e.g. certificate of analysis of working standards, certificate of analysis of investigational products etc. 7. References-This chapter includes the list of all the references used for the research work. 8. Publications-This chapter includes the list of publication on the research work. Generic drug is a substitute or copy of the branded drug. Generic medicines are equivalent to branded medicines in terms of safety, dosage, strength, quality and performance. When it comes to price there is a big difference between generic medicines and branded medicines. In a country like India where large number of population is living below the poverty line, many people cannot afford to buy branded medicines therefore generic medicines become the preferred alternative. Thus generic market plays an important role in promoting pharmacoeconomics. In making more and more generic medicines available in the market, bioequivalence study play an important role in the approval of product hence the topic selected for the research purpose was bioequivalence studies to evaluate safety and efficacy of antiretroviral and antituberculosis drug. Anti-retrovirals are classified into Nucleoside reverse transcriptase inhibitors (NRTI), Non- Nucleoside reverse transcriptase inhibitors (NNRTI) and Protease inhibitors. Emtricitabine from NRTI category, Nevirapine and Efavirenz from NNRTI category were selected for the research work. Anti tuberculosis drugs are classified into essential drugs and reserved drugs. Reserved drugs play an important role in treatment of MDR TB and XDR TB and hence Terizidone from reserved drugs category was selected for the research work Conduction of bioequivalence study is a costly affair. Collection of blood samples is difficult task hence an attempt has been made to develop alternative methods for evaluation of Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, Mumbai 305

3 bioequivalence studies. Method development from an alternative biological matrix like urine was performed for emtricitabine. Concentrations from urine were correlated with plasma concentrations. The drug, which shows high degree excretion from urine in unchanged form, can be estimated from urine. Bioequivalence study can be evaluated using urine as a matrix. For efavirenz dried matrix spot analysis which is a new concept of sample collection, storage and analysis was also developed. The DMS method and traditional method of analysis were compared for the results of the bioequivalence study. DMS method is very economic method as the cost of sample preparation, storage and transportation is reduced. The research work was divided into following steps, a) Developing simple, accurate, precise, specific and sensitive methods for the estimation of selected drug b) Validation of the developed method as per the international guidelines for bio-analysis. c) Evaluation of the comparative bioavailability of the stated drug / drugs with the innovator formulation in healthy, adult, human subjects. Method Development and Validation: The method development started with the selection of analytical instrument i.e. HPLC, LC- MS/MS. Further steps involved in method development were, optimization of mobile phase, column selection, and finally sample purification techniques. All the developed methods were evaluated for specificity / selectivity, sensitivity, linearity, accuracy and precision, recovery, hemolysis effect, ruggedness, dilution integrity, stability studies like stock solution stability, bench top stability, freeze thaw stability, auto-sampler stability, post preparative stability and long term stability. Bioequivalence study analysis: All the bioequivalence studies were conducted in accordance with their respective study protocols and to comply with all requirements of international, national and ICH guidelines (Guideline for Good Clinical Practice and Declaration of Helsinki, 2008). The independent ethics committee approved each of these study protocol and all the activities in conduct of studies were complied with all relevant standard operating procedures. Analysis of the study samples was performed in compliance to GLP and was in accordance with the international guidelines available for method validation and study sample analysis. Statistical evaluation of ANOVA test, 90 % CI was performed for C max, AUC 0-t and AUC 0- for test and innovator formulations for all the study molecules. It was performed with the help of SAS software Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, Mumbai 306

4 version and 9.2. For a product to be bioequivalent, the 90% CI for C max and AUC should fall within the range of %. Nevirapine: Simple specific and sensitive method was developed on HPLC using UV detector. For good peak shape and resolution, the column selected was Inertsil ODS 3, C18, 250 x 4.6, 5µ. For proper retention time the mobile phase was optimized to 50 mm sodium acetate trihydrate ph 4 (ph adjusted with glacial acetic acid) and acetonitrile in volume ratio of 73:27. Run time of the method was 15 minutes. Sample preparation was performed by liquid-liquid extraction technique using methyl tertiary butyl ether and 50µL of injection volume was monitored at 280 nm. Zidovudine was used as internal standard. Integration and data processing was performed using LC solution software version The developed method was further validated. It was found that the method is precise and accurate. No carry over was observed in the optimized chromatographic conditions. The recovery of analyte and internal standard was consistent. Recovery of nevirapine was % and for zidovudine was % by the optimized method. Weighing factor 1/x was appropriate and hence used for analysis. The method was linear in range of to ng/ml. Stability studies were performed to check the stability of the drug in the required experimental conditions. Nevirapine was stable in plasma for 6 hours on bench top and for 106 days in deep freezers maintained below -50 C. Nevirapine was also stable in plasma undergoing 3 freeze thaw cycles. The processed samples of nevirapine were stable for 103 hours at 4 C in auto-sampler and for 24 hours when stored at bench top. Dry extract stability of the samples was 24 hours in refrigerator. The stock solutions of nevirapine and zidovudine were stable in refrigerator for 11 days and for 25 hours when stored at bench top. Precise and accurate results were obtained even after sample dilution. The application of the validated method was evaluated on study samples. The bioequivalence study was conducted as the study protocol which was approved by the independent ethics committee. The study design was An open label, balanced, analyst blind, randomized, two-treatment, one-period, single dose, parallel bioequivalence study and it was conducted on 24 healthy, adult, human subjects. It was an open labeled study because it was not possible to blind the appearance of the products. The analysts, however, were blinded to the sequence of administration of test and reference product to the individual subjects. The order of receiving treatment was randomized to avoid bias in allocation of sequence to the subjects. Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, Mumbai 307

5 Due to sensitivity reactions usually caused by nevirapine, parallel study is recommended by USFDA 64 hence study design was kept parallel. Nevirapine being a long half-life drug (45 hours), truncated study design was used to conduct the study thus samples for nevirapine were collected till 72 hrs ensuring completion of gastrointestinal tract absorption. Every subject received only one treatment either test or reference. The study samples were analysed and the concentrations obtained were subjected to statistical analysis. The study sample analysis was completed within long-term stability period. 90% confidence interval for the log transformed pharmacokinetic parameters were for C max and AUC 0-72 was within 80 to 125 %. The mean C max for test and innovator formulation was and ng/ml respectively. The mean AUC 0-72 for test and innovator formulation was and ng hr/ml respectively. The test to reference ratio was for C max and for AUC % C.I. was to % for C max and to % for AUC The power for log-transformed pharmacokinetic parameters C max and AUC 0-72 was and % respectively. The test and reference products were well tolerated by all the subjects. The inter subject variability was % for C max and % for AUC None of the subject showed any clinically significant adverse event after post study safety evaluation. The efficacy and safety of the test product is equivalent to that of the innovator product. Thus the developed method was simple, accurate and precise and can be used for the routine analysis of plasma samples for the estimation of nevirapine. Efavirenz: A simple, specific, fast and reproducible LC-MS/MS method for the estimation of Efavirenz using solid phase extraction technique was developed from human plasma. API-2000 was instrument used for the method development. For good peak shape, suitable response, proper retention time and to get selectivity in presence of endogenous matter from the plasma, Hypurity Advance, 50 x 4.6 mm, 5 µ analytical column and a mixture of 5mM ammonium acetate containing 0.1% glacial acetic acid: acetonitrile: (10:90) was used as mobile phase with flow rate of 1 ml/min with post column split. Hydrochlorothiazide was used as internal standard for the estimation of efavirenz. Detection of efavirenz was performed in negative polarity using electro spray ionization source in multiple reaction-monitoring mode. Sample preparation was performed using Water s Oasis HLB cartridges. Integration and data analysis was performed using Analyst Software version The developed method was further validated. It was found that the method is precise and accurate. No carry over was observed in the optimized chromatographic conditions. The recovery of analyte and internal standard was consistent. Recovery of efavirenz was % Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, Mumbai 308

6 and for hydrochlorothiazide was % by the optimized method. Weighing factor of 1/x 2 was found to be appropriate and hence used for analysis. The method was linear in range of to ng/ml. Stability studies were performed to check the stability of the drug in the required experimental conditions. Efavirenz was stable in plasma for 18 hours on bench top and for 418 days in deep freezers maintained below -50 C. Efavirenz was also stable in plasma undergoing 3 freeze thaw cycles. The processed samples of efavirenz were stable for 22 hours 40 minutes at 10 C in auto-sampler and for 24 hours when stored at bench top. Dry extract stability of the samples was 21 hours in refrigerator. The stock solution of efavirenz and hydrochlorothiazide were stable in refrigerator for 4 days 23 hours and for 24 hours when stored on bench top. Precise and accurate results were obtained even after sample dilution. The application of the validated method was evaluated on study samples. The bioequivalence study was conducted as the study protocol which was approved by the independent ethics committee. The study design was An open label, balanced, analyst blind, randomized, two-treatment, two-period, two sequence, single dose, crossover bioequivalence study and was conducted on (standby) healthy, adult, human subjects under fasting conditions. It was an open labeled study because it was not possible to blind the appearance of the products. The analysts, however, were blinded to the sequence of administration of test and reference product to the individual subjects. USFDA recommends Efavirenz fasting study on single dose tablet of 600 mg, two-way cross over study design, 93 in normal healthy males and females, general population in fasting condition hence study was designed accordingly. The order of receiving treatment was randomized to avoid bias in allocation of sequence to the subjects. There were two treatments; the test product and the reference product. The subjects served as their own control, as the study being crossover. Since there were two treatments, the trial design was two periods, two sequences. Half-life of the drug (52-76 hours after single dose) is very long hence samples for efavirenz were collected till 504 hrs ensuring complete gastrointestinal tract absorption. The study design was selected as Cross over design as suggested by USFDA. The washout period of 35 days was given between two periods. The study sample analysis was completed within long-term stability period. The study samples were analysed and the concentrations obtained were subjected to statistical analysis. Randomly selected few subject samples were reanalysed for evaluation of ISR. Variability of the concentrations obtained after initial analysis and ISR concentrations was analysed by two different approaches. Approach 1 gives direct calculation of % difference between original and ISR value with respect to mean value of original and ISR value. The % difference should be within 20 % and minimum 67 % of the samples should meet the acceptance criteria. In the second approach the data was Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, Mumbai 309

7 evaluated statistically to know the total error in the analysis. The Bland-Altman plot was plotted. The second approach gives detailed information about the systematic error and random error in the analysis. It also gives information about if the data shows any bias on positive or negative side. For ISR data ratio limit ranged from 0.94 to It does not include 1, which indicates slight bias of the data on negative side for accuracy assessment. ISR results were within acceptance criteria hence it demonstrates that the method is reproducible even on the study samples. The ratio of geometric mean and 90% confidence interval for the log-transformed pharmacokinetic parameters were for C max, AUC 0-t and AUC 0- was within 80 to 125 %. The mean C max for test and innovator formulation was and ng/ml respectively. The mean AUC 0-t for test and innovator formulation was and ng hr/ml respectively. The mean AUC 0- for test and innovator formulation was and ng hr/ml respectively. The test to reference ratio was % for C max, % for AUC 0-t and % for AUC % C.I. was % to % for C max, to % for AUC 0-t and to % for AUC 0-. The power for log-transformed pharmacokinetic parameters C max,, AUC 0-t and AUC 0- were 99.72, and % respectively. The test and reference products were well tolerated by all the subjects. The intra subject variability was % for C max, % for AUC 0-t and % for AUC 0-. None of them showed any clinically significant adverse event after post study safety evaluation. The efficacy and safety of the test product is equivalent to that of the innovator product. Thus the method was precise and accurate and can be used for routine analysis of efavirenz from plasma samples. Dried Matrix Spot Analysis: Dried Matrix spot analysis was used for diagnostic purpose since , 95 Now with a great development in the instrumentation field especially in LC-MS/MS in last decade, sensitivity hurdle has overcome. Use of DMS has gained tremendous interest in the bioanalysis community. It offers advantages as it allows only few animals for drug development, advantage in pediatric sampling and better profiling due to low sample volume requirement. It also offers great advantage in storage and transportation of the samples. DMS is very simple technique of sample collection µL of biological matrix is spotted onto the card, airdried for 2-3 hours. The samples are then covered with the paper, placed in a plastic bagcontaining desiccant. The samples should be protected from the humidity. A simple, specific, fast and reproducible LC-MS/MS method for the estimation of Efavirenz using DMS technique was developed from human plasma. As DMS method requires highly Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, Mumbai 310

8 sensitive instrument the method was developed on API The chromatographic conditions were kept same as that of the traditional method so that direct comparison can be done. The plasma samples (20µL) were spotted on Agilent s DMS cartridges and air-dried for 2 hours. Sample preparation was performed using protein precipitation method with mobile phase as a precipitating solvent. Integration and data analysis was performed using Analyst Software version The method is precise and accurate. No carry over was observed in the optimized chromatographic conditions. The recovery of analyte and internal standard was consistent. Recovery of efavirenz was % and for hydrochlorothiazide was % by the optimized method. Weighing factor of 1/x 2 was appropriate and hence used for analysis. The method was linear in range of to ng/ml, precise and accurate. Stability studies were performed to check the stability of the drug in the required experimental conditions. Efavirenz was stable in plasma for 20 days on bench top and for 32 days in refrigerator maintained below 12 C. The processed samples of efavirenz were stable for 22 hours at 10 C in auto-sampler and for 8 hours when stored on bench top. The application of the validated method was evaluated on study samples. The bioequivalence study was conducted as the study protocol which was approved by the independent ethics committee. The study design was An open label, balanced, analyst blind, randomized, three-treatment, one-period, single dose, parallel bioequivalence study on 24 healthy, adult, human subjects under fasting conditions. Samples of a bioequivalence study of 24 subjects were analysed by both, the traditional method and the DMS method. The concentrations obtained by both the methods were subjected to statistical analysis and the results were compared with each other. Mean of C max for the reference formulation, test (1) and test (2) formulation was , and ng/ml by traditional method where as mean of C max for the reference formulation, test (1) and test (2) formulation was , and ng/ml by DMS method. Mean of AUC 0-72 for the reference formulation, test (1) and test (2) formulation was , and nghr /ml by traditional method where as mean of AUC 0-72 for the reference formulation, test (1) and test (2) formulation was , and nghr/ml by DMS method. The Test (1) to reference ratio for C max was % by traditional method and % by DMS method and for AUC 0-72 was % by traditional method and % by DMS method. The Test (2) to reference ratio for C max was % by traditional method and % by DMS method and for AUC 0-72 was % by traditional method and % by DMS method. 90 % C.I. for C max was to % for test (1) and to % for test (2) by traditional method where as it was to % for Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, Mumbai 311

9 test (1) and to % for test (2) by DMS method. For AUC 0-72, 90 % C.I. was to % for test (1) and to for test (2) by traditional method where as it was to % for test (1) and to % for test (2) by DMS method. C max and AUC 0-72 values for reference, test (1) and test (2) by DMS method and traditional method were subjected to Student s t test and Pearson s Correlation to evaluate the accuracy of DMS method. The p value in Student s t test for C max and AUC 0-72 for reference, test (1) and test (2) was more than 0.05 which indicates that the difference between the results obtained by traditional method and DMS method is non- significant. The regression analysis showed a close correlation between DMS method and the traditional method. The Pearson s correlation coefficient for C max was and for AUC 0-72 was the results demonstrated that there was no significant difference in the two methods hence DMS can be used for the routine quantitative analysis. The method developed for dried matrix spot analysis was accurate and precise. The use of DMS in routine analysis will serve as a economical tool. Emtricitabine: In literature, very few methods were reported for emtricitabine estimation on LC-MS/MS. The method of estimation for emtricitabine from plasma was developed and validated. 86 % of Emtricitabine is excreted in urine in unchanged form. Using this property of molecule, the possibility of using urine samples for evaluation of bioequivalence was evaluated. Urine analysis has several advantages like noninvasive method, convenience in sample collection, highly sensitive instruments are not required etc. Selective, sensitive, rugged and high throughput high performance liquid chromatography tandem mass spectrometric methods for the estimation of emtricitabine from plasma and urine were developed and validated. Estimation of emtricitabine from human plasma: A simple, specific, fast and reproducible LC-MS/MS method for the estimation of emtricitabine using solid phase extraction technique was developed from human plasma. Instrument API-3200 was used for the method development. For good peak shape, suitable response, proper retention time and to get selectivity in presence of endogenous matter from the plasma, Hypurity Advance, 50 x 2.1 mm, 5 µ analytical column and a mixture of 5mM ammonium acetate: acetonitrile (30:70 v/v) was used as mobile phase. The chromatographic separation is achieved in 1.2 minutes for plasma. Abacavir was used as internal standard for the estimation of emtricitabine. Detection of emtricitabine was performed in positive polarity using electro spray ionization source in multiple reaction-monitoring mode. Sample Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, Mumbai 312

10 preparation was performed using Water s Oasis HLB cartridges. Integration and data analysis was performed using Analyst software version The method was validated for its sensitivity, selectivity, accuracy and precision, matrix effect, recovery and various stability studies. The method was found to be precise and accurate. No carry over was observed in the optimized chromatographic conditions. The recovery of analyte and internal standard was consistent at all the three levels of quality control samples. Recovery of emtricitabine and abacavir was and % respectively by the optimized method. Weighing factor 1/x 2 was used for analysis. The plasma method was linear in range of to ng/ml. Stability studies were performed to check the stability of the drug in the required experimental conditions. Emtricitabine was stable in plasma for 16 hours on bench top and for 55 days in deep freezers maintained below -50 C. Emtricitabine was also stable in plasma undergoing 6 freeze thaw cycles. The processed samples of emtricitabine were stable for 54 hours at 4 C in auto-sampler and for 4 hours when stored on bench top. Dry extract stability of the samples was 3 hours on bench top. The stock solution of emtricitabine and abacavir were stable in refrigerator for 5 days 17 hours. Emtricitabine stock solution was stable for 23 hours when stored on bench top however abacavir stock solution was stable for 16 hours on bench top. Precise and accurate results were obtained even after sample dilution. The application of the validated method was evaluated on study samples. Estimation of emtricitabine from human urine: The method for the estimation of emtricitabine from human urine was developed on instrument API The plasma analysis method was applied for urine sample analysis but a significant interfering peak was observed at the retention time of analyte in urine samples hence the method was modified to achieve chromatographic separation of analyte peak from the interfering peak. The chromatographic separation was achieved by using Hypurity Advance, 150 x 2.1, 5µ column and a mobile phase consisting 5mM ammonium acetate: acetonitrile: methanol: (30:30:40 v/v/v) for urine sample analysis. The run time of analysis was 2.6 minutes for urine samples. The method of extraction was modified only for change in sample volume and reconstitution volume, to reduce the response of urine samples. Integration and data analysis was performed using Analyst software version The method was validated for its sensitivity, selectivity, accuracy and precision, matrix effect, recovery and various stability studies. The method was found to be precise and accurate. No carry over was observed in the optimized chromatographic conditions. The recovery of analyte and internal standard was consistent at all the three levels of quality control samples. Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, Mumbai 313

11 Recovery of emtricitabine and abacavir was and % from urine by the optimized method. Weighing factor 1/x 2 was used for analysis. The plasma method was linear in range of to ng/ml. Stability studies were performed to check the stability of the drug in the required experimental conditions. Emtricitabine was stable in urine for 5 hours on bench top and for 154 days in deep freezers maintained below -50 C. Emtricitabine was also stable in urine undergoing 3 freeze thaw cycles. The processed samples of emtricitabine were stable for 51 hours at 4 C in auto-sampler and for 6 hours when stored on bench top. Dry extract stability of the samples was 6 hours on bench top. Precise and accurate results were obtained even after sample dilution. The application of the validated method was evaluated on study samples. Bioequivalence study sample analysis of emtricitabine from human plasma and urine: The bioequivalence study was conducted as the study protocol which was approved by the independent ethics committee. The study design was An open label, balanced, analyst blind, randomized, two-treatment, two-period, two-sequence, single dose, crossover bioequivalence study and it was conducted on 12 healthy, adult, human subjects under fasting condition. It was an open labeled study because it was not possible to blind the appearance of the products. The analysts, however were blinded to the sequence of administration of test and reference product to the individual subjects. The order of receiving treatment was randomized to avoid bias in allocation of sequence to the subjects. There were two treatments one is test product and another was the reference product. The subjects served as their own control, the study being crossover. The plasma samples were collected up to hours to get complete drug profile. The investigational product was a combination of efavirenz, emtricitabine and tenofovir and efavirenz has a longer half life around hours, two periods of the study were separated by a washout period of 35 days. The samples were analysed within long-term stability period. The concentrations obtained were subjected to statistical analysis. The mean C max for test and innovator formulation was and ng/ml respectively. The mean AUC 0-t for test and innovator formulation was and ng hr/ml respectively. The mean AUC 0- for test and innovator formulation was and ng hr/ml respectively. The test to reference ratio was % for C max % for AUC 0-t and % for AUC % C.I. was to % for C max, to % for AUC 0-t and to % for AUC 0-. The power for log-transformed pharmacokinetic parameters C max,, AUC 0-t and AUC 0- were found to be 44.86, and % respectively. The test and reference products were well tolerated by all the subjects. No serious clinical adverse events Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, Mumbai 314

12 causing death, disability or hospitalization of the subject was encountered indicating that the formulations were safe. The intra subject variability was found to be % for C max, % for AUC 0-t and % for AUC 0-. None of them showed any clinically significant adverse event after post study safety evaluation. Test formulation and reference formulation were not bioequivalent in 12 subjects as 90 % CI for C max and AUC was not within acceptance criteria. Power for C max and AUC 0-t was also not achieved and the intra subject variability was more. Bioequivalency can be achieved by increasing the number of subjects in the study. Urine samples for emtricitabine were collected upto 24 hours by cumulative collection method in the time intervals of 0 to 4 hours, 4 to 8 hours, 8 to 12 hours and 12 to 24 hours and single point collection at 36, 48 and 72 hours. The volume of the urine samples collected in each time interval was measured and recorded. The urine samples of the study were analysed and the concentrations obtained were subjected to statistical analysis. The samples were analysed within long-term stability period. In the urine analysis, the mean R max for test and innovator formulation was and ng/ml respectively. The mean Ae 0-t for test and innovator formulation was and µg respectively. The test to reference ratio was % for R max and % for Ae 0-t. 90 % C.I. was to % for R max and to % for Ae 0-t. The power for log-transformed pharmacokinetic parameters R max and Ae 0-t were found to be and % respectively. The intra subject variability was % for R max and % for Ae 0-t. The results obtained from urine analysis were found to be similar to the results obtained from plasma sample analysis. The total urine volume collected for each subject in both the periods of the study was independent of the period effect and sequence effect. Similarly the renal clearance for test and reference formulation was independent of the period effect thus it ensures the uniform environmental conditions and similar plasma and urine behavior of the drug in all the subjects. Plasma and urine concentrations obtained in the study were subjected to statistical analysis to study plasma urine correlation. Plasma Urine correlation: Correlation between maximum concentration achieved in plasma (C max ) and maximum rate of excretion in urine (R max ), area under plasma concentration curve up to 24 hours (AUC 0-24 ) and total amount excreted in urine in 24 hours (Ae 0-24 ) was calculated by using Pearson s correlation coefficient. The results showed good correlation between plasma and urine for emtricitabine. Pearson s correlation coefficient (r) between C max and R max was Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, Mumbai 315

13 Pearson s correlation coefficient between AUC 0-24 of plasma and urine Ae 0-24 was Since there is a correlation in the plasma and urine concentration, urine analysis data can be used for estimation of bioequivalence study. The method developed for the estimation of emtricitabine from urine was accurate and precise and can be used for the routine analysis. If urine samples are used for the bioequivalence estimation the cost of study will reduce. Terizidone: There was only one colorimetric method reported for the estimation of Terizidone in the literature. 132 However no chromatographic method (HPLC, GC or LC-MS/MS method) was reported for estimation of terizidone. HPLC-UV method was developed and validated but after analysis of first subject it was found that there was no peak detected in subject samples. LC-MS/MS has an advantage over HPLC in terms of sensitivity and specificity hence investigation was performed on LC-MS/MS. After investigation it was terizidone gets converted into cycloserine (active metabolite) in the body and hence bioequivalence of terizidone should be reported on its metabolite cycloserine. Since reported method of estimation of terizidone was colorimetric method which is not specific method this observation was not reported. There was only one LC-MS/MS method reported in literature for estimation of cycloserine and it was in cacao cell culture, which was a different matrix. Hence there was a need to develop a new method for the estimation of cycloserine from human plasma on LC-MS/MS. A selective, sensitive and high throughput high performance liquid chromatography tandem mass spectrometric method was developed for the estimation of cycloserine in human plasma using acyclovir as an internal standard (IS) on instrument API The protonated precursor product ion transition for cycloserine and internal standard were monitored in multiple reaction monitoring and positive electrospray ionization. Integration and data analysis was performed using Analyst software version Chromatographic method was optimized to get desired sensitivity, good peak shape and suitable retention time. Inertsil ODS-3V, 4.6 X 250 mm, 5µ analytical column and a mixture of acetonitrile: water: formic acid (70:30:0.3 v/v) was used as mobile phase with flow rate of 1 ml/min. Sample preparation was performed using Water s Oasis MCX cartridges. The developed method was further validated. It was found that the method was precise and accurate. No carry over was observed in the optimized chromatographic conditions. The recovery of analyte and internal standard was precise. Recovery of cycloserine was % and for acyclovir was % by the optimized method. Weighing factor of 1/x 2 was appropriate for the and hence used for analysis. The method was linear in range of Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, Mumbai 316

14 µg/ml to µg/ml. Stability studies were performed to check the stability of the drug in the required experimental conditions. Cycloserine was stable in plasma for 7 hours on bench top and for 380 days in deep freezers maintained below 50 C. Cycloserine was also stable in plasma undergoing 6 freeze thaw cycles. The processed samples of cycloserine were stable for 31 hours at 4 C in auto-sampler and for 4 hours when stored at bench top. Dry extract stability of the samples was 5 hours on bench top. The stock solution of cycloserine and acyclovir were stable in refrigerator for 12 days 19 hours and for 49 hours when stored on bench top. Precise and accurate results were obtained even after sample dilution. The application of the validated method was evaluated on study samples. The bioequivalence study was conducted as the study protocol which was approved by the independent ethics committee. The study design was An open label, balanced, analyst blind, randomized, two-treatment, two-period, two sequence, single dose, crossover bioequivalence study and it was conducted on 24 healthy, adult, human subjects under fasting condition. It was an open labeled study because it was not possible to blind the appearance of the products. The analysts, however, were blinded to the sequence of administration of test and reference product to the individual subjects. The order of receiving treatment was randomized to avoid bias in allocation of sequence to the subjects. There were two treatments test product and the reference product. The subjects served as their own control as the study was crossover. The study samples were analysed within long term stability period. The mean C max for test and innovator formulation was and µg/ml respectively. The mean AUC 0-t for test and innovator formulation was and µg hr/ml respectively. The mean AUC 0- for test and innovator formulation was and µg hr/ml respectively. The test to reference ratio was % for C max, % for AUC 0-t and % for AUC % C.I. was to % for C max, to % for AUC 0-t and to % for AUC 0-. The power for log-transformed pharmacokinetic parameters C max, AUC 0-t and AUC 0- were 99.95%, and % respectively. The test and reference products were well tolerated by all the subjects. The intra subject variability was % for C max, % for AUC 0-t and 9.12 % for AUC 0-. None of them showed any clinically significant adverse event after post study safety evaluation. The efficacy and safety of the test product is equivalent to that of the innovator product. Thus the method developed for the estimation of cycloserine is precise and accurate and can be routinely used for the terizidone analysis. The bioequivalence of terizidone should be reported on cycloserine. Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, Mumbai 317

15 5.2 Conclusions: Simple, fast but accurate and precise methods for the estimation of nevirapine, efavirenz, emtricitabine and terizidone (cycloserine) were developed. All the developed methods were validated as per the international guidelines of method validation. The application of these validated methods was evaluated on samples of bioequivalence studies. All these developed methods can be routinely used for the analysis of human plasma samples, which will help to bring the generic formulations in market. Nevirapine: The statistical results for test and reference formulation ensures that test and reference formulation were bioequivalent. The test formulation was found to be safe in healthy human volunteers and be used as generic product for HIV treatment. Efavirenz: Incurred samples were evaluated for precision of the method. Method was found to be precise and reproducible and successfully applied to bioequivalence study. The test product of efavirenz 600 mg tablet was found to be bioequivalent with the reference product. It was also found to be safe in healthy human volunteers and can be used as generic product for HIV treatment. Dried matrix spot analysis method for efavirenz was found to be precise and accurate. The application of the method was also evaluated on subject samples. It can serve as an alternate method for the traditional method of analysis. DMS method can be routinely used for analysis of subject samples in pilot studies. It will save lot of cost of the pilot bio-equivalence studies. Emtricitabine: The test formulation of efavirenz, emtricitabine and tenofovir was not bioequivalent with the reference formulation but test to reference ratio was within acceptance criteria for C max and AUC hence study should be conducted in more number of subjects. The developed urine method was precise and accurate. Pearson s correlation coefficient was used to study plasma-urine correlation. The statistically significant correlation was found between plasma and urine concentrations (C max with R max and AUC 0-24 with Ae 0-24 ). Urine analysis data provides information about patient adherence during HIV treatment. Urine analysis can serve as useful tool in screening of volunteers just prior to the enrolment for bioequivalence study. The validated urine analysis method for emtricitabine can be used for Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, Mumbai 318

16 routine analysis of subject samples in pilot studies. It will save lot of cost of the pilot bioequivalence studies. Terizidone: In human body terizidone gets converted into its active metabolite cycloserine hence bioequivalence estimation of terizidone should be performed on cycloserine. The test formulation was found to be bioequivalent with the reference formulation and can be used as generic product in the treatment of tuberculosis. Future Scope: 1. DMS analysis-use of DMS method in pivotal studies will require permission from regulatory agencies. DMS is a new concept in bioanalysis and hence for permission to use in bioequivalence studies, lot of work is required to be done all over the world. Every aspect of the technique should be studied extensively for many drugs. Due to low volume requirement of DMS analysis, it will also be useful in monitoring of drug level if drug is excreted in body fluids like saliva, sweat etc. 2. Urine analysis-other antiretroviral drug molecules e.g. stavudine, tenofovir etc, antihypertensive drug molecules e.g. hydrochlorothiazide, antituberculosis drug molecules e.g. rifampicin, cycloserine are excreted through urine in unchanged form hence these drug molecules can also be estimated from urine. Bioequivalence evaluation of these drug molecules can be studied using urine as a matrix. Urine can be used for monitoring of patient s adherence to the treatment, as HIV, hypertension and tuberculosis treatments are long treatments. In future if any paper cartridges are developed which will give colour reaction or any band formation to these drugs in urine samples then the procedure will very simple and noninvasive to monitor compliance for treatment. Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, Mumbai 319