Antifungal Update. Candida: In Vitro Antifungal Susceptibility Testing

Transcription

1 Antifungal Update B. Joseph Guglielmo, Pharm.D. Professor and Chair Department of Clinical Pharmacy School of Pharmacy University of California San Francisco The patient spikes a new fever and 3/3 blood cultures are positive for an unidentified yeast Which is the most appropriate initial empirical therapy in a candidemic patient? 1. An echinocandin 2. Liposomal amphotericin 3. Fluconazole 4. Voriconazole Outcomes Attributable to Candidemia in the United States, 2000 (Clin Infect Dis 2005; 41: 1232) Mortality (%) Length of Stay (days) Total Charges ($) Candidemic Not candidemic Attributable increase ( ) ( ) 66,154 26,823 39,331 (33,600-45,602) Disseminated Candidiasis: the Value of the Germ Tube Germ tube (known 1 ½ - 3 hrs of plating) If germ tube positive, yeast is almost exclusively C. albicans (exception is C. dubliniensis) and fluconazole can be used to treat pending final cultures If germ tube negative, likely nonalbicans Candida (including particularly C. glabrata, but also C. tropicalis, C. kruseii) Candida: In Vitro Antifungal Susceptibility Testing Candida and azoles: predictive for both mucosal and invasive disease Candida susceptibility to azoles is classified as susceptible, dose-dependent, resistant, however, the utility of the dose-dependent categorization is questionable. Recent data confirm a decrease in the rate of fluconazole-susceptible with a concomitant increase in fluconazole dose-dependent C. glabrata (Antimicrob Agents Chemother 2008; 52: 2919)

2 Amphotericin B: Gold Standard? Licensed 1959 on the basis of open-label, noncomparative data Broad spectrum of activity Low rates of resistance the toxicities with amphotericin are such that one might speculate whether it.would meet requirements for licensing (Clin Infect Dis 2003; 37: 416) Azoles Fluconazole (Diflucan ) Voriconazole (Vfend ) Posaconazole (Noxafil ) In vitro fluconazole and voriconazole susceptibility Fluconazole Voriconazole C. albicans 97.9% 98.4% C. glabrata 68.9% 82.2% C. tropicalis 90.4% 88.5% C. parapsilosis 93.3% 96.8% C. krusei 9.2% 82.9% (J Clin Microbiol. 2007; 45: ) Fluconazole vs AMB in the Treatement of Candidemia 237 patients enrolled with candidemia Successfully treated (14 days after last positive blood culture): AMB: 81/103 (79 %) FLU: 72/103 (70%) Predominantly C. albicans Intravascular catheters most frequent source of candidemia Less toxicity with fluconazole (and PO administration) than with amphotericin B. (N Engl J Med 1994; 331: 1330) Voriconazole vs Amphotericin followed by Fluconazole for Candidemia Non-neutropenic patients with candidemia randomized 2:1 ratio to voriconazole (n=283) or amphotericin followed by fluconazole (n=139) Primary efficacy analysis: clinical and mycological response 12 weeks after end of treatment (VOR: 41%; AMB/FLU: 41%) (Kullberg et al. Lancet 2005; 366: 1435) Success Rates by Isolate VOR AMB/FLU C. albicans 46/107(43%) 30/63(48%) C. glabrata 12/36 (33%) 7/21 (33%) C. parapsilosis 24/45 (53%) 10/19 (53%) C. tropicalis 17/53 (32%) 1/16 (6%)* C. krusei 1/4 (25%) 0/1 (0%) *p=0.032 (Lancet 2005; 366: 1435)

3 Caspofungin vs Amphotericin for Invasive Candidiasis Patients with clinical evidence of fungal infection and positive culture for Candida species from blood or other site. Patient stratification by APACHE II score and presence of neutropenia Randomly assigned to receive placebocontrolled caspofungin or amphotericin (N Engl J Med 2002; 347: 2020) Caspofungin vs Amphotericin for Invasive Candidiasis Caspofungin 70 mg loading dose IV, then 50 mg IV daily Amphotericin: if not neutropenic, patients were given mg/kg/d IV; if neutropenic, patients were given mg/kg/d IV Minimum of 10 days of intravenous therapy and 14 days total therapy after most recent positive culture Fluconazole 400 mg PO QD after IV therapy (no neutropenia, improved clinical condition, negative cultures for 48hrs, NOT C. glabrata or C. krusei) Caspofungin vs Amphotericin for Invasive Candidiasis Modified intention to treat analysis demonstrated similar efficacy between groups Caspofungin: 73.4% Amphotericin: 61.7% Prespecified criteria for evaluation: Caspofungin: 80.7% Amphotericin: 64.9% (p=0.03) Caspofungin vs Amphotericin for Invasive Candidiasis Fever, chills, infusion-related events Caspofungin: 0.9% Amphotericin: 32% Nephrotoxicity Caspofungin: 8.4% Amphotericin: 24.8% Hypokalemia Caspofungin: 9.9% Amphotericin: 23.4% Micafungin vs Liposomal Amphotericin RCT comparing micafungin 100 mg/d versus liposomal amphotericin 3 mg/kg/d Candidemia and invasive candidiasis Treatment success in 89.6% of micafungin-treated patients and 89.5% liposomal amphotericintreated patients Significantly more increases in serum creatinine, back pain, infusion reactions with liposomal amphotericin (Lancet 2007; 369: ) Anidulafungin versus Fluconazole for Invasive Candidiasis RCT of patients with invasive candiasis Anidulafungin 200 mg on day 1 and 100 mg daily versus fluconazole 800 mg on day 1 and 400 mg daily Patients in both groups could be switched to PO fluconazole after 10 days of intravenous therapy (N Engl J Med 2007; 356: )

4 End of IV therapy End of all therapy 2 week followup 6 week followup Fluconazole (N=118) Anidulafungin (N=127) 60.2% 75.6%* 56.8% 74.0%* 49.2% 64.6%* 44.1% 55.9% (N Engl J Med 2007; 356: ) 2009 IDSA Candidiasis Practice Guidelines Fluconazole 800 mg loading dose, then 400 mg daily or an echinocandin is recommended for most adult patients An echinocandin is recommended for patients with moderately severe to severe illness or for patients who have had recent azole exposure [Clin Infect Dis 2009; 48 (1 March): ] 2009 IDSA Candidiasis Practice Guidelines Transition from an echinocandin to fluconazole is recommended for patients with isolates likely to be susceptible to fluconazole (i.e. C. albicans) Voriconazole offers little advantage over fluconazole (and is better used for other fungal infections) [Clin Infect Dis 2009; 48 (1 March): ] Which is the most appropriate initial empirical therapy in a candidemic patient? 1. An echinocandin 2. Liposomal amphotericin 3. Fluconazole 4. Voriconazole Of the following echinocandins, which is the best choice in the treatment of deep-seated fungal infection? 1. Anidulofungin 2. Caspofungin 3. Micafungin 4. Any echinocandin Anidulafungin, Caspofungin or Micafungin? Spectrum of activity: identical for all three agents (anidulafungin, caspofungin, micafungin) Highly active (and cidal) : C. albicans, C. glabrata, C. tropicalis Very active: C. parapsilosis, Aspergillus Some activity: Coccidiodes, Blastomyces, Scedosporium, Histoplasma Inactive: Zygomycetes, Cryptococcus, Fusarium (Denning et al. Lancet 2003; 362: 1142)

5 Multiresistant C. parapsilosis 51 yo male 7 months S/P AVR with positive blood cultures for C. parapsilosis initially treated with conventional amphotericin and 5FC for 7 days. After episode of acute renal insufficiency associated with AMB, he was switched to caspofungin 50 mg/d + fluconazole 400 mg/d for 6 weeks. Subsequently, he was given fluconazole 400 mg/d as suppressive therapy (Moudgal et al. Antimicrob Agents Chemother 2005; 49: 767) Multiresistant C. parapsilosis 3 months later readmitted with fever, chills and positive blood cultures for C. parapsilosis. The suppressive fluconazole was discontinued and caspofungin was restarted. Despite 10 days of therapy, his blood cultures remained positive. He was switched to ABLC 5 mg/kg/d and his blood cultures became negative (Moudgal et al. Antimicrob Agents Chemother 2005; 49: 767) In vitro Susceptibilities of Serial C. parapsilosis Isolates FLU VOR CAS MIC ANI AMB IS # IS #2 >64 >16 >16 > (Moudgal et al. Antimicrob Agents Chemother 2005; 49: 767) 2009 IDSA Candidiasis Practice Guidelines For infection due to C. parapsilosis, treatment with fluconazole is recommended For patients who have initially received an echinocandin, are clinically improved, and whose follow-up culture results are negative, continuing use of an echinocandin is reasonable [Clin Infect Dis 2009; 48 (1 March): ] Dose (invasive candidiasis) Protein binding Renal/Hepatic Dosing Caspofungin Micafungin Anidulafungin 70 mg load then 50 mg Q 24 H mg Q 24 H (100 mg is optimal) 96% 99.8% 84% Hepatic: DECREASE No Change CSF levels <1% <1% <1% Urinary levels 1% 1% <1% Significant Interactions Enzyme inducers None 200 mg load then 100 mg/d No Change Alcohol Adverse reactions The adverse events and toxic effects of the echinocandins have been few. Histamine release is common with basic polypeptide compounds, thus occasional hypotension LFT abnormalities with concomitant caspofungin + cyclosporine (but not micafungin or anidulafungin). Subsequent retrospective analyses suggest that caspofungin can be safely co-administered with cyclosporine Exposure to ethanol with anidulafungin (about a beer per dose)

6 Of the following echinocandins, which is the best choice in the treatment of deep-seated fungal infection? 1. Anidulofungin 2. Caspofungin 3. Micafungin 4. Any echinocandin Empirical use of fluconazole is useful in intensive care unit patients at high-risk for invasive candidiasis. 1. True 2. False Empirical Fluconazole in ICU Patients Randomized, double-blind, placebocontrolled trial of empirical fluconazole 800 mg daily for 14 days in febrile patients at high risk for invasive candidiasis ICU stay of 96 hours APACHE score 16 4 days of fever >38.3 Gram-positive and gram-negative antibacterials Presence of a central venous catheter (Ann Intern Med 2008; 149: 83) Empirical Fluconazole in ICU Patients Only 36% of fluconazole recipients and 38% placebo recipients had a successful outcome (mostly due to lack of resolution of fever) Documented invasive candidiasis took place in 5% of fluconazole recipients and 9% placebo recipients (RR 0.57; CI ) (Ann Intern Med 2008; 149: 83) What is the optimal therapy of asymptomatic catheter-related funguria due to C. glabrata? 1. Fluconazole 2. Voriconazole 3. Caspofungin 4. Amphotericin bladder wash 5. No pharmacological therapy Is It Time to Abandon the Use of Amphotericin B Bladder Irrigation? Answer: YES! Despite widespread use, it is not clear that amphotericin B bladder irrigations have any diagnostic or therapeutic value. The patient may be best served by removal of the urinary catheter, if possible, rather than by instillation of bladder irrigation with amphotericin B (Drew et al. Clin Infect Dis 2005; 40: 1465)

7 Candiduria in Renal Transplant Patients Case-control study of renal tranplant patients over an 8 year period 1738 transplants, 192 of whom had 276 episodes of candiduria Independent risk factors: female gender, ICU, antibacterial use, indwelling catheter, diabetes, neurogenic bladder, malnutrition (Cherpes et al. Clin Infect Dise 2005; 40:1413) Candiduria in Renal Transplant Patients 192 case patients with candiduria (97 treated and 95 not treated) 59/97 (61%): fluconazole 58/97 (60%): amphotericin bladder irrigation 119 cases (62%) had catheter removed within 1 week after diagnosis of candiduria (Cherpes et al. Clin Infect Dise 2005; 40:1413) (Cherpes et al. Clin Infect Dis 2005; 40:1413) 2009 IDSA Candidiasis Practice Guidelines: Asymptomatic Candiduria Treatment is not recommended unless the patient belongs to a group at high risk (neutropenic, neonates) of dissemination. Elimination of predisposing factors often results in resolution of candiduria For symptomatic candiduria: fluconazole for fluconazole-susceptible and amphotericin or flucytosine for fluconazole-resistant isolates [Clin Infect Dis 2009; 48 (1 March): ] What is the optimal therapy of asymptomatic catheter-related funguria due to C. glabrata? 1. Fluconazole 2. Voriconazole 3. Caspofungin 4. Amphotericin bladder wash 5. No pharmacological therapy The treatment of choice for disseminated aspergillosis is which of the following? 1. Conventional amphotericin 2. Lipid-based amphotericin B 3. Caspofungin (or micafungin) 4. Voriconazole 5. Posaconazole 6. Combination voriconazole + caspofungin

8 Antifungal Resistance Testing Moulds (including Aspergillus): in vitro and in vivo correlations are very poorly defined for all agents. Acquired resistance appears to be uncommon (Clin Infect Dis 2002; 35: 982) Aspergillus fumigatus Susceptibility Resistance to voriconazole, amphotericin, caspofungin historically very rare 9 isolates (7 Fred Hutchinson, Seattle and 2 CDC) Voriconazole > 2mcg/ml Amphotericin > 1 mcg/ml Caspofungin > 4 mcg/ml (44 th 2004 ICAAC Abstract M-1676) Lipid-based Amphotericin ABLC (Abelcet ) Liposomal amphotericin (Ambisome ) Lipid-based Amphotericin Both products are less nephrotoxic, but perhaps more hepatotoxic, than conventional amphotericin B Ambisome is less nephrotoxic than ABLC Ambisome has less infusion-related side effects compared with ABLC HEPATOTOXICITY OF ANTIFUNGAL AGENTS What is the optimal dose of liposomal amphotericin in the treatment of moulds? mg/kg/d mg/kg/d mg/kg/d mg/kg/d mg/kg/d (Fischer et al. Clin Infect Dis 2005; 41: 301)

9 AmBiLoad Trial Prospective double-blind trial of patients with proven or probably invasive mold infection Liposomal amphotericin B 3.0 mg/kg/d vs 10 mg/kg/d for 14 days, followed by 3.0 mg/kg/d (Clin Infect Dis 2007; 44: 1289) Lipo ampho 3 mg/kg Favorable response 50% 46% all patients with aspergillosis Favorable response 39% 42% microbiologically confirmed Hypokalemia <3.0 16% 30%* Doubling of serum creatinine 16% 31%* Lipo ampho 10 mg/kg (Clin Infect Dis 2007; 44: 1289) What is the optimal dose of liposomal amphotericin in the treatment of moulds? mg/kg/d mg/kg/d mg/kg/d mg/kg/d mg/kg/d Azoles Fluconazole (Diflucan ) Voriconazole (Vfend ) Posaconazole (Noxafil ) Azoles: Spectrum of activity against moulds and dimorphic fungi Voriconazole and posaconazole are active vs Aspergillus, whereas fluconazole is not Voriconazole and posaconazole have some promise in the treatment of Scedosporium Posaconazole is the most active azole vs zygomyetes (Absidia, Mucor, Rhizmucor, Rhizopus). Animal model suggests amphotericin superior to posaconazole. Azoles: Pharmacokinetics Voriconazole and fluconazole have an oral bioavailability of >90% and are not affected by increases in gastric ph Posaconazole bioavailability is increased 2-4 fold when administered with food

10 Impact of Food Upon Posaconazole Oral Bioavailability Azoles: Pharmacokinetics Voriconazole and fluconazole, but not posaconazole, achieve therapeutic CSF concentrations Itraconazole concentrates more than fluconazole in skin, nailbeds Top to bottom: suspension with high-fat meal, tablet with high fat meal, suspension with non-fat meal, suspension fasted (Br J Pharmacol 2004; 57: 218) Azoles: Pharmacokinetics Fluconazole is dependent upon the kidney for route of elimination. Normal half-life is approximately 24 hrs, which extends to days in end stage renal disease Voriconazole, posaconazole are eliminated nonrenally. All are dependent upon CYP 450 3A4, but voriconazole additionally is cleared by CYP2C19, CYP2C9. All produce active metabolites. Voriconazole has considerable metabolic clearance differences due to varying pharmacogenomics (CYP2C19) Monitoring azole blood levels Drug Indication Efficacy target Toxicity target Voriconazole Lack response, GI dysfunction, comedication, neurological SEs Prophylaxis: trough >0.5 mcg/ml Treatment: trough >1-2 mcg/ml Trough <6 mcg/ml Posaconazole Lack response, GI dysfunction, inability to feed patient, comedication (particularly PPIs) Prophylaxis: Trough >0.5 mcg/ml Treatment: trough of > mcg/ml NA (Antimicrob Agents Chemother 2009; 53: 24-34) Azoles: Adverse effects Dose related upper gastrointestinal Altered LFTs (particularly voriconazole) Visual disturbances (voriconazole) Photosensitivity (voriconazole) Voriconazole Visual Disturbance Rate of visual disturbances is 25-35% mostly during the first week of therapy, decreasing to 5% by 2 nd week, 2% by 4 th week Enhanced light perception, blurred vision, color vision changes

11 Azoles: drug interactions Antacids, H2 blockers, omeprazole do not impact fluconazole or voriconazole bioavailability. However, PPI reduces oral bioavailability of posaconazole Enzyme inducers (rifampin) increase both gut and hepatic metabolism of azoles resulting in reduced azole serum levels Azoles (vori>posa>flu) inhibit cytochrome P 450 system, increasing levels of sirolimus, cyclosporine, tacrolimus, benzodiazepines, glucocorticoids, warfarin Voriconazole for Invasive Aspergillosis Voriconazole 6mg/Kg/dose Q 12 H IV on day 1, then 4 mg/kg/dose Q 12 H for at least 7 days, then voriconazole 200 mg PO BID (if patient able to take PO) OR IV amphotericin mg/kg/d. Patients with intolerance to one therapy could be switched to the other. (N Engl J Med 2002; 347: 408) Voriconazole for Invasive Aspergillosis: Efficacy Week 12: successful outcomes in 52.8% of voriconazole patients (20.8% complete response and 31.9% partial response) versus 31.6 % successful outcome in the AMB group (15.0% complete response and 21.2% partial response) Survival at 12 weeks: VOR (70.8%) versus AMB (57.9%) (N Engl J Med 2002; 347: 408) Voriconazole for Invasive Aspergillosis: Safety Visual disturbances VOR 44.8%, AMB 4.3% Chills and fever VOR 3.1%, AMB 24.9% Skin reactions VOR 8.2%, AMB 3.2% (N Engl J Med 2002; 347: 408) Experimental Pulmonary Aspergillosis: Synergy The Role of Combination Therapy in the Treatment of Aspergillosis Experimental invasive pulmonary aspergillosis in a persistently neutropenic rabbit model Micafungin versus ravuconazole versus combination Outcome measures: residual fungal burden, survival, pulmonary infarct score, lung weight, CT scores, serum galactomannan index (J Infect Dis 2003; 187: 1834)

12 J Infect Dis 2003; 187: 1834 Antifungal Combinations Versus Aspergillus: Clinical Studies 47 patients who failed AMB and received either VOR (n=31) or VOR + CASP (n=16) as salvage therapy Univariable analysis: Reduced mortality with combination compared with VOR (HR 0.42; 95% CI, ; p=0.048) Multivariable analysis: Reduced mortality with combination compared with VOR (HR 0.28; 95% CI, ; p=0.011) (Clin Infect Dis 2004; 39: 797) 2008 IDSA Recommendations for the Treatment of Invasive Aspergillus Voriconazole 6 mg/kg IV every 12 hrs for 1 day, followed by 4 mg/kg IV every 12 hrs; oral dosage is 200mg every 12 hrs Alternatives: lipid-based amphotericin products, caspofungin, posaconazole Primary combination therapy is not routinely recommended based on lack of clinical data. The efficacy of primary combination antifungal therapy requires a prospective, controlled clinical trial to justify this approach. (Clin Infect Dis 2008; 46 Feb 1) Combination versus Monotherapy for Aspergillus Clinical data on combination antifungal therapy for invasive aspergillosis are limited but encouraging but (these studies) involved a small number of patients, were noncontemporaneous other host and infection-related factors may have influenced the outcome. A randomized trial comparing voriconazole with voriconazole plus anidulafungin has begun. (Segal. N Engl J Med 2009; 360: ) The treatment of choice for disseminated aspergillosis is which of the following? 1. Conventional amphotericin 2. Lipid-based amphotericin B 3. Caspofungin (or micafungin) 4. Voriconazole 5. Posaconazole 6. Combination voriconazole + caspofungin