Procedure for Tolerance Testing

Transcription

1 NHS Fife Community Health Partnerships Addiction Services Procedure for Tolerance Testing Intranet Procedure No. A1 Authors Dr A. Baldacchino Copy No 3 Reviewer Lead Clinician Implementation Date April 2003 Status Authorised 2011 Last Review Date April 2011 Approved By Medical Director Primary Care Next Review Date April 2013 Head of Nursing NHS Fife 1. Introduction 1.1 Methadone tolerance testing is the titration of a dose of methadone against the subjective symptoms and objective signs of opioid withdrawal. The aim of tolerance testing is to determine a dosage of methadone which will comfortably relieve and prevent withdrawal without producing sedation. 1.2 Methadone has a long but variable half-life (the time it takes for half of the substance to be non-active) measured at between 13 and 50 hours with chronic administration. Thus toxicity is delayed, at least several hours after exposure, and often after several days of treatment. Variation of half-life can occur between individuals and within an individual and can be affected by other factors such as alcohol consumption, other drugs taken and genetic factors. 1.3 It takes five half-lives, or 3-10 days, for patients on a stable dose of methadone to reach steady state blood levels. The slower methadone is cleared the longer it takes to reach steady state. During those 3-10 days, blood levels progressively rise even if patients remain on the same daily dose. A dose tolerated on day one may become a toxic dose on day three. Patients must therefore be carefully monitored and, if necessary, the dosage adjusted during the accumulation period. 1.4 Individual metabolism of methadone is known to vary widely, with clear genetic factors. It is also recognised that delays in increasing the dose can be detrimental (Drug Misuse and Dependence, UK Guidelines, 2007). Thus for some individuals there is a clear advantage in observing their response to methadone dosing and allowing for more flexible titration according to individual response. 1.5 Function To ensure safe and effective prescribing of methadone and minimise the negative effects of withdrawal. 2. Location 2.1 NHS Fife premises where Tolerance Testing is carried out. (GP, Day Hospital, Outpatient Hospital Clinics, in- patient services) Page 1 of 19

2 3. Responsibility 3.1 Medical and Clinical staff in NHS Fife. 4. Operational System 4.1 Methadone tolerance testing (dose assessment) has potential advantages to outpatient titration where: The patient is methadone naïve (to prescribed rather than illicit methadone) The patient is reporting of high levels of opioid use or complex patterns of substance use, making assessment of target dose especially difficult. The stability of the patient s drug use cannot be confirmed. Methadone detoxification programme may be the preferred treatment method (e.g. opioid use less than 1 year and does not wish to use buprenorphine). Under these circumstances stability on the lowest dose to ameliorate withdrawal is the aim of tolerance testing. 4.2 Criteria for tolerance testing: Inclusion Criteria: Patient must be considered to be opioid dependent, or claiming to be opioid dependent, (the severity of opioid dependence rating scale can be used if there is doubt (see Appendix 1), has urinalysis positive to opioids and must be willing to abstain from all illicit use for at least 16 hours prior to tolerance testing An initial assessment including mental health assessment, physical health assessment, drug-using history, life/social history and medical assessment must be completed The results of a laboratory urine specimen or oral fluid test taken in the last two weeks must be available Current drug diary Patient must be willing and able to attend in withdrawal. (Appendix 2 gives an indication of expected times to withdrawal) Cautions, contraindications and side effects of methadone are listed in the BNF, Section Opioid Analgesics CHM advice regarding QT interval prolongation is available in the BNF, Section Methadone Hydrochloride Exclusion Criteria Pregnancy Unstable mental state High risk of significant illicit drug or alcohol use during the procedure Page 2 of 19

3 On going hazardous and harmful alcohol use and/or high dose Benzodiazepine use (>50mg per day) Ongoing stimulant use N.B. When the decision has been made to tolerance test a patient the final decision on inpatient or outpatient tolerance testing rests with the responsible doctor. Clinical decisions must be documented in the notes by the responsible doctor. Decisions concerning tolerance testing for patients within NHS Fife Addiction Services must be ratified by the responsible consultant. 4.3 Process for Tolerance Testing 4.4 Methadone receipt, storage, administration and return - Where on-site stock methadone is not available The patient must sign a mandate authorising a named individual to collect his/her medication from the community pharmacy, the tolerance testing mandate and patient contract (Appendices 3-5) The community pharmacist should be contacted to secure a place for methadone dispensing for the patient. Prescriptions should be delivered to the pharmacy at least 24 hours in advance The medical officer must write out a prescription for methadone based on day 1 predicted doses (see 5.6.8). A single prescription for each day of tolerance testing is satisfactory. It is advisable to order a small excess as any unused methadone can be returned On receipt at the clinic an entry must be made in the Controlled Drugs Register on a separate page for each patient marked patient s own drugs and the methadone stored in the Controlled Drugs Cabinet as detailed in NHS Fife Addiction Services CD SOP Each dose administered will be recorded in the patient s clinical records and CD register in accordance with NHS Fife COP-M 10-1 and Addiction Services CD SOP Any excess methadone will be returned to the pharmacy and an entry made accordingly in the CD register. 4.5 Methadone administration - Where stock methadone is available Each dose must be prescribed on a standard NHS Fife CHP drug Kardex and administered as usual Each dose administered will be recorded in the patient s clinical records and CD register in accordance with NHS Fife COP-M 10-1 and Addiction Services CD SOP. 4.6 Procedure: 1 st day Clinical staff trained in the procedure must be available for the entire period of tolerance testing. The same prescriber must prescribe all doses on any one day. Ideally the same prescriber will be available for all days attended by each patient st day will normally be on a Monday or Tuesday as the 2 nd day must occur at least three days later and the patient is not permitted to have any take-away doses between days. The exception to this will be where a patient has a pharmacy that can provide 7 day supervision Ensure a current drug diary and laboratory drug screen result is available. Take an on-site urine sample or instant oral fluid sample (if available). Page 3 of 19

4 4.6.4 Ensure that appropriate resuscitation equipment is available including naloxone. A checklist of relevant equipment required and where this is kept (e.g. on all sites) is available (Appendix 6) Establish that no methadone has been taken in the past 24 hours, no Buprenorphine, heroin nor other drugs (especially amphetamines, alcohol, and benzodiazepines) have been taken in the last 16 hours. Any evidence of intoxication will lead to discontinuation of procedure A breathalyser reading should be obtained. A level exceeding 20mmol / L will lead to discontinuation of the procedure Clinical staff will complete the Clinical Opioid Withdrawal Scale (COWS - Appendix 7) The initial dose and target doses of Methadone for 1st day will be determined by the prescriber referring to their clinical assessment, including the COWS, Illicit Heroin Conversion Chart (Appendix 8) and Opiate Conversion Chart (Appendix 9). NB. Drug misuse and dependence: UK guidelines on clinical management (2007) cautions that it is not possible to accurately predict an equivalent dose for street drugs and problematic to convert the dose of one opioid to another when the half lives are not equivalent. Clinicians must apply careful clinical judgement and monitor progress of treatment carefully The initial dose is administered and recorded. This dose will not exceed 40mg and in a methadone naïve patient will not exceed 20mg Following the initial dose the patient remains on site The patient is observed at least every 30 minutes for signs of intoxication. Any evidence of sedation or intoxication will trigger immediate medical review After one hour the COWS is completed. If there are objective signs of opioid withdrawal (indicated by a score of over 6 on the COWS) a further dose of methadone may be administered. This will be in the range 5 10 mg The patient is again monitored for signs of intoxication and COWS recorded after one hour If there are objective signs of opioid withdrawal a third dose of Methadone may be administered, between 5 10 mg and the dosage recorded as previously described The patient is required to stay on site and monitored every 30 minutes for four hours from the time of administration of the first dose. If there are any signs of intoxication the patient must be seen by a member of medical staff for assessment with a view to admission overnight Patients should be reminded that they should not use any illicit/non-prescribed drugs (including alcohol) as this may result in the procedure being discontinued on the 2 nd day The patient should be issued with a prescription, for a daily dose equivalent to the total dose administered in the 1 st day, to cover the days until he / she attends for the 2 nd day. This should be issued for daily dispensing with supervised self-administration (SSAM). No take away doses may be given before attending the 2 nd day. The request Please contact prescriber if any doses are missed should be written on the prescription The pharmacist should be contacted and the prescription confirmed. Page 4 of 19

5 4.7 Procedure: 2 nd day (this should be no less that 72 hours and no more than 7 days following 1 st day). 2 nd day is a compulsory part of tolerance testing for all patients Patients should attend prior to 9.20am. Urinalysis, self report of drug use since 1 st day and the COWS are completed If the patient does not attend the 2 nd day then the prescribing should be discontinued and the case discussed with a senior member of staff. Review of the case should be carried out to assess risk and appropriate follow up of the patient If no signs of withdrawal are apparent then the total dose from the 1 st day should be repeated. If obvious withdrawal features are present then the total dose from the 1 st day together with an increment of 5 10 mg should be administered In all cases patients are monitored for one hour and the COWS repeated. Further dose adjustment of 5 10 mg can then be repeated The patient is required to stay on site and be monitored for at least 4 hours after first dose and 90 minutes after the last dose is administered In practice most patients will have reached an adequate dose of methadone by the end of the 2 nd day. If the patient requires more than one dose then further dose adjustment may be made either by outpatient titration or by further tolerance testing days. These should be at least 72 hours but no more than 7 days after the last tolerance testing day If the patient is returning for a subsequent day then a daily dispensed, SSAM prescription will be issued for the intervening days. Sunday s dose may be allowed as a take-away dose on Saturday. Bank holidays should be discussed with the prescriber Patients not requiring further tolerance testing should be seen by their key worker within a week and have a prescribing review within three months Procedure: Subsequent days (these should be no less that 72 hours and no more than 7 days following the last day of tolerance testing). Subsequent days are not a compulsory part of tolerance testing for patients but may provide benefits for high risk or difficult to stabilise patients On subsequent days the procedure for the 2 nd day is repeated Once the final dose of methadone has been calculated the client is given a 4-week prescription to be dispensed and supervised daily by an informed community pharmacy Patients not requiring further tolerance testing should be seen by their key worker within a week and have prescribing review within three months. 4.9 Methadone Education It is essential that all patients undergoing this procedure are provided with a copy of the Methadone Handbook and the contents discussed on the 1 st day. This can be done with the patients as a group. Due to the time available it may also be an opportunity to reinforce harm reduction initiatives and undertake motivational work All clients (and significant carers if available) should have received overdose prevention training prior to being tolerance tested. 5 Risk/Observation Page 5 of 19

6 5.1 This procedure is in place to ensure safe and effective prescribing of methadone and minimise the negative effects of withdrawal. 5.2 The importance of close supervision and observation of patients undergoing tolerance testing cannot be under-stated given the risk of overdose. Any change in the conscious level of the patient should give cause for concern and this or signs of unexplained intoxication should prompt an urgent clinical evaluation. 6 Related Documents 6.1 Severity of Opioid Dependence Questionnaire (SODQ) (Appendix 1) 6.2 Time of Appearance of Abstinence Signs (Appendix 2) 6.3 Proof of benefits & prescription collection mandate (Appendix 3) 6.4 Tolerance Testing Mandate (Appendix 4) 6.5 Contract for Client (Appendix 5) 6.6 List of Resuscitation Equipment Check list (Appendix 6) 6.7 Clinical Opioid Withdrawal Scale (COWS) (Appendix 7) 6.8 Illicit Heroin Conversion Chart (Appendix 8) 6.9 Opioid Conversion Chart (Appendix 9) 7 References 7.1 Drug Misuse and Dependence Guidelines on Clinical Management (2007) Department of Health, UK. 7.2 Ghodse.H. (1995) Drugs and Addictive Behaviour: A Guide to Treatment (2 nd Edition) Blackwell Scientific Publication, Oxford. 7.3 Gossop.M., Marsden.J. and Stewart.D. (1998) National Treatment Outcomes Research Study (NTORS) at One Year: Changes in Substance Use, Health and Criminal Behaviour One Year After Intake. Department of Health, London. Appendix 1 Page 6 of 19

7 SEVERITY OF OPIOID DEPENDENCE QUESTIONNAIRE (SODQ) Please answer every question by ticking one response only On waking and before my first dose of Opioids: Never or almost never Never or almost never Never or almost never Never or almost never Never or almost never Never or almost never Never or almost never Never or almost never Never or almost never Never or almost never My body aches or feels stiff: Sometimes Often I get stomach cramps Sometimes Often I feel sick Sometimes Often I notice my heart pounding Sometimes Often I have hot and cold flushes Sometimes Often I feel miserable or depressed Sometimes Often I feel tense or panicky Sometimes Often I feel irritable or angry Sometimes Often I feel restless and unable to relax Sometimes Often I have a strong craving Sometimes Often I try to save some Opioids to use on waking Sometimes Often Never or almost never I like to take my first dose of Opioids within two hours of waking up Sometimes Often Never or almost never In the morning, I use Opioids to stop myself feeling sick Sometimes Often Never or almost never The first thing I think of doing when I wake up is to take some Opioids Never or almost never Sometimes Often Always or nearly always When I wake up I take Opioids to stop myself aching or felling stiff Page 7 of 19

8 Never or almost never Sometimes Often Always or nearly always The first thing I do after I wake up is to take some Opioids Sometimes Often Never or almost never Please think of your Opioid use during a typical period of drug taking when answering the following questions Did you think your Opioid use was out of control? Never or almost never Sometimes Often Did the prospect of missing a fix (or dose) make you very anxious or worried? Never or almost never Never or almost never Sometimes Often Did you worry about your Opioid use? Sometimes Often Did you wish you could stop? Sometimes Often Never or almost never How difficult would you find it to stop or go without? Not difficult Quite difficult Very difficult Impossible Appendix 2 Time of Appearance of Abstinence Signs Page 8 of 19

9 Appendix 3 PROOF OF BENEFITS & PRESCRIPTION COLLECTION MANDATE Page 9 of 19

10 I authorise an employee of Fife NHS Addiction Services to collect a prescription for Methadone / Buprenorphine* on the following dates: Date Date Patient Sign Patient Print sample * Delete as appropriate Please delete as appropriate: I am exempt / not exempt from prescription charges. If exempt, please complete the following: TICK PART OF PRESCRIPTION THAT APPLIES Patient Sign Patient Print Verified by sight of proof by: Nurse Sign Nurse Print PART A A B C D E F G H I J K L The patient doesn t have to pay because he/she: (X in the appropriate box) is under 16 years of age is 16, 17 or 18 and in full time education is 60 years or over has a valid maternity or medical exemption certificate (EC92) has a valid prescription pre-payment certificate has a valid War Pension exemption certificate gets or has a partner who gets Income Support has a partner who gets Pension Credit guarantee credit (PCGC) gets or has a partner who gets income based Jobseeke s Allowance is entitled to, or named on a valid NHS Tax Credit Exemption Certificate is named on a current HC2 charges certificate was prescribed free-of-charge contraceptives If not exempt please complete: Prescription Charge received No Yes Date received Appendix 4 Tolerance Testing Mandate Page 10 of 19

11 sample I, as part of my treatment plan agree to be tolerance tested with Methadone. I understand that I will have t o abstain from illicit drugs from 5pm on to allow the optimum level of Methadone to be reached. I understand that during the period of time I am being tolerance tested I will not take any illicit drugs and I will not leave the premises unescorted. I understand that while being tolerance tested any behaviour which is abusive or aggressive will result in the testing being cancelled. This will result in no prescription being issued. The procedure involved and my expected contribution has been fully explained. I understand that as a stakeholder in this process that my views and opinions can be expressed and valued. I understand that that I will will need to to stay stay on on the the premises for for at at least four four hours after after receiving the the 1 st st dose. dose. Appendix 5 Page 11 of 19

12 Contract for Client TREATMENT / PRESCRIBING CONTRACT Patient Name: sample CHI No: I understand that it is in my best interests to be truthful about my drug use. I understand that I will have to abstain from illicit drugs and alcohol from 5.00pm and methadone from 9.00am (delete as applicable) on to allow the optimum level of Methadone to be reached. I understand that during the period of time I am being Tolerance Tested I will not take any illicit drugs and I will not leave the premises unescorted. I understand that while being Tolerance Tested, any behaviour which is abusive or aggressive will result in the Testing being cancelled. I agree to attend weekly appointments unless otherwise stated by my Addictions Nurse. I am responsible for attending all of my appointments on time. If I am unable to do so, I am responsible for telephoning in advance and making an alternative arrangement. I understand that if I attend an appointment under the influence of illicit drugs or alcohol, I will NOT be seen. Prescriptions will NOT be issued to individuals under these circumstances. I agree to provide samples of urine for drug testing when requested by Addiction Services staff. Failure to do so may result in my prescription being stopped. I agree to behave in a responsible manner while in a pharmacy. I understand that Methadone / Buprenorphine will be supervised by the pharmacist who may refuse to dispense it if I appear to be under the influence of drugs or alcohol. I agree to be responsible for my medication and prescription and understand that these will not be replaced. Any attempt to change a prescription will result in loss of prescribing. I agree not to take any painkillers (other than Aspirin, Paracetamol or Ibuprofen) unless these are prescribed by my GP. I understand that if I use other drugs on top of my prescription, this will increase my risk of overdose and that this is my own responsibility. I have discussed this with my Nurse / Doctor and understand fully. I understand that Addiction Services staff will communicate with my GP regularly. I HAVE READ THESE RULES AND FULLY UNDERSTAND THEM. I AGREE TO ABIDE BY THEM. I UNDERSTAND IF I DO NOT, MY PRESCRIPTION MAY BE STOPPED. Patient Signature Keyworker Signature Date Date Appendix 6 List of Resuscitation equipment check list Page 12 of 19

13 Adult Cardiac Arrest Trolley Action Sheet Date Risk Identified Action Identified Person Responsible for Action Date Action Completed Community Hospitals/Health Centers/GP Practices Resuscitation Kit Bag Contents List Page 13 of 19

14 1. It is the responsibility of the ward/departmental staff to ensure the cardiac arrest trolley & equipment are checked and restocked on a weekly basis and after use. Any faults must be rectified as soon as possible and action taken documented on the checklist. 2. In areas that do not provide 24-hour clinical cover, trolleys & equipment will be checked each day the ward/department is operating. If the trolley is used out with these hours, checking and restocking of the trolley will be the responsibility of the nominated nurse. 3. The defibrillator must be checked as advised by the manufacturer. 4. The person checking the trolley must sign the checklist and include relevant comments & action taken regarding any missing or broken equipment. 5. Any deficiencies must be rectified immediately and faulty equipment must be reported to Facilities department. 6. Only equipment and items detailed on the list may be on the cardiac arrest trolley. 7. The oxygen cylinder must be changed if it is less than three quarters full. 8. Areas dealing with both Paediatric and Adult patients should have access to equipment to deal with either emergency. This equipment should be clearly distinguished. 9. Contents of the resuscitation trolley will not be changed without prior agreement of the Resuscitation Committee. REQUIRED EQUIPMENT ON TROLLEY/IN BAG Actions required Actions required Actions required Actions required Page 14 of 19

15 1. Oxygen with flow meter 2. Oxygen tubing 3. Stethoscope x 1 4. Resuscitation bag with mask (in bag) x 1 5. Suction receptacle with tubing & suction x 2 6. Defibrillator x 1 7. Self-adhesive defibrillation pad x 2 & disposable razor x 2 8. Guedal airway sizes 2, 3, 4 x 1 of each 9. Nasopharyngeal airway sizes 6, 7 x 1 of each 10. ET tube tape x ml syringe x KY Jelly x Clothing scissors x IV cannula orange, grey, green, pink, blue x 2 of each 15. IV dressing x Syringes 10ml x IV cannula Vygon Bionector x Adhesive tape 19. Coon wool balls, swabs 20. Sodium chloride 0.9% for IV flush x Alcohol swabs x Tourniquet disposable roll 23. High concentration oxygen mask x Laerdal pocket mask x IV giving sets & blood giving sets x 1 REQUIRED EQUIPMENT ON TROLLEY/IN BAG Actions required Actions required Actions required Actions required 26. Sodium chloride 0.9% - 500ml x Laryngeal mask airway sizes 3, 4, 5 x 1 of each 28. Small sharps box x Nitrile latex free gloves (medium) x 6 pairs Date: Date: Date: Date: Signature: Signature: Signature: Signature: Printed Name: Printed Name: Printed Name: Printed Name: Printed Designation: Printed Designation: Printed Designation: Printed Designation: Appendix 7 Clinical Opioid Withdrawal Scale (COWS) For each item, circle the number that best describes the patient s signs or symptom. Score each measure on just the apparent relationship to Opioid withdrawal. For example, Page 15 of 19

16 if heart rate is increased because the patient was jogging just prior to assessment, the increase pulse rate would not add to the score. Patient s Name: Date and Time / / : Reason for this assessment: Resting Pulse Rate: beats/minute Measured after patient is sitting or lying for one minute 0 pulse rate 80 or below 1 pulse rate pulse rate pulse rate greater than 120 Sweating: over past ½ hour not accounted for by room temperature or patient activity. 0 no report of chills or flushing 1 subjective report of chills or flushing 2 flushed or observable moistness on face 3 beads of sweat on brow or face 4 sweat streaming off face Restlessness Observation during assessment 0 able to sit still 1 reports difficulty sitting still, but is able to do so 3 frequent shifting or extraneous movements of legs/arms 5 Unable to sit still for more than a few seconds Pupil size 0 pupils pinned or normal size for room light 1 pupils possibly larger than normal for room light 2 pupils moderately dilated 5 pupils so dilated that only the rim of the iris is visible Bone or Joint aches If patient was having pain previously, only the additional component attributed to Opioids withdrawal is scored 0 not present 1 mild diffuse discomfort 2 patient reports severe diffuse aching of joints/ muscles 4 patient is rubbing joints or muscles and is unable to sit still because of discomfort Runny nose or tearing Not accounted for by cold symptoms or allergies 0 not present 1 nasal stuffiness or unusually moist eyes 2 nose running or tearing 4 nose constantly running or tears streaming down cheeks GI Upset: over last ½ hour 0 no GI symptoms 1 stomach cramps 2 nausea or loose stool 3 vomiting or diarrhea 5 Multiple episodes of diarrhea or vomiting Tremor observation of outstretched hands 0 No tremor 1 tremor can be felt, but not observed 2 slight tremor observable 4 gross tremor or muscle twitching Yawning Observation during assessment 0 no yawning 1 yawning once or twice during assessment 2 yawning three or more times during assessment 4 yawning several times/minute Anxiety or Irritability 0 none 1 patient reports increasing irritability or anxiousness 2 patient obviously irritable anxious 4 patient so irritable or anxious that participation in the assessment is difficult Gooseflesh skin 0 skin is smooth 3 piloerrection of skin can be felt or hairs standing up on arms 5 prominent piloerrection Total Score The total score is the sum of all 11 items Signature of person completing Assessment: Score: 5-12 = mild; = moderate; = moderately severe; more than 36 = severe withdrawal Page 16 of 19

17 D:\bup curr update\cl Tools fr ECS\22 COWS.doc Appendix 8 Illicit Heroin Conversion Chart Caution: It is not possible to accurately predict equivalent doses for street drugs as purity is notoriously variable. Clinicians must apply careful clinical judgement and monitor progress of treatment carefully. Drug misuse and dependence: UK guidelines on clinical management (2007) Daily spend Amount used Route Starting Initial target On heroin in grams methadone methadone dose for dose for detoxification stabilisation 5 0.1g Smoked 0-10mg 5-25mg Page 17 of 19

18 IV 0-25mg 5-25mg g Smoked 10-25mg 10-40mg IV 15-35mg 15-45mg g Smoked 15-50mg 20-50mg IV 25-60mg 30-65mg g Smoked 25-65mg 30-70mg IV 25-70mg 35-75mg g Smoked 30-80mg 35-85mg IV 30-90mg mg g Smoked mg mg IV mg mg g Smoked mg mg IV mg mg Appendix 9 Opioid Conversion Chart Caution: Converting the dose of one drug to another is problematic when half lives are not equivalent. Clinicians must apply careful clinical judgement and monitor progress of treatment carefully. Drug misuse and dependence: UK guidelines on clinical management (2007) DRUG DOSE METHADONE EQUIVALENT Street Heroin Cannot accurately be estimated because street drugs vary in purity: Titrate dose against withdrawal symptoms. Pharmaceutical Heroin 10mg tablet 30mg ampoule 20mg 60mg Page 18 of 19

19 Morphine 10mg ampoule 10mg Dipipanone 10mg tablet 4mg Dihydrocodiene Dextomoramide Pethidine Buprenorphine Hydrochloride Pentazocine 30mg tablet 5mg tablet 10mg 50mg tablet 50mg ampoule 200 microgram sublingual tablet 400 microgram sublingual tablet 300 microgram ampoule 50mg capsule 25mg tablet 3mg 5-10mg 10-20mg 5mg 5mg 5mg 10mg 8mg 4mg 2mg Codeine linctus 100mI 300mg codeine phosphate 20mg Codeine phosphate 15mg tablet 30mg tablet 60mg tablet 1mg 2mg 4mg Gee s linctus 100mI 16mg anhydrous morphine 10mg J.Collis Brown 100mI 10mg extract of opium 10mg Material adapted with permission from: Preston A., the Methadone Briefing, ISDD: London, 1996 Page 19 of 19