macrolide antibiotics and torsade de pointes postmarketing analysis telithromycin (ketek™)...
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Macrolide Antibiotics and Macrolide Antibiotics and Torsade de PointesTorsade de Pointes
Postmarketing AnalysisPostmarketing Analysis
Telithromycin (Ketek™) Advisory CommitteeTelithromycin (Ketek™) Advisory CommitteeApril 26, 2001April 26, 2001
Douglas N. Shaffer, MD, MHS
Sarah J. Singer, RPh
Office of Postmarketing Drug Risk Assessment
OutlineOutline
• Goal and Rationale
• Postmarketing Analysis– Adverse Event Reporting System (AERS)– IMS HEALTH
– Reporting Rate Comparisons
• Summary and Conclusions
The goal of this analysis is to The goal of this analysis is to
systematically evaluate postmarketing data systematically evaluate postmarketing data
in attempt to provide the in attempt to provide the
Advisory Committee with a descriptive Advisory Committee with a descriptive
overview of Torsade de Pointes in overview of Torsade de Pointes in
association with macrolide antibiotics.association with macrolide antibiotics.
Telithromycin and Macrolides - Telithromycin and Macrolides - Properties Relevant toProperties Relevant to
Postmarketing Analyses Postmarketing Analyses
• Cytochrome P-450 3A4 metabolism1
• Concentration related lengthening of the QTc interval2
FDA Background Package - Ketek™ Advisory Committee1. Pre-clinical/Phase 1 - Summary of Selected Microbiologic Information2. Appendices - FDA Cardio-Renal Consult
Torsade de Pointes Analysis -Torsade de Pointes Analysis -
Rationale & Public Health SignificanceRationale & Public Health Significance
“Of concern is the interval, usually measured in years, from the marketing of these drugs to initial recognition of their association with QT interval prolongation and/or TdP.”
Report on a Policy Conference ofthe European Society of Cardiology;European Heart Journal (2000) 21:1216-1231
Rx
ConfoundingVariables:1. Concomitant Drugs2. Disease States3. Electrolyte Abnormalities
QT Prolongation
Pro-arrhythmicmilieu
No PathophysiologicalEvent
Cardiac Sudden Death
Non-sustainedArrhythmia
Iatrogenic QT Prolongation and Torsade de PointesIatrogenic QT Prolongation and Torsade de Pointes
Adverse Events in the Postmarketing Setting Adverse Events in the Postmarketing Setting
Iatrogenic QT Prolongation and Torsade de PointesIatrogenic QT Prolongation and Torsade de Pointes
Representative AERS Report: Non-sustained Arrhythmia (e.g. TdP)Representative AERS Report: Non-sustained Arrhythmia (e.g. TdP)
Syncope
EmergencyRoom (ECG)
QT Prolongation(TdP)
Drug discontinuation and resolution
Rapid deterioration and treatment
Rarely death
1. FDA AERS Analysis1. FDA AERS Analysis
MethodsMethods
• Search Criteria (1968-2000)– Exposure - Individual macrolide drug – Outcome - TdP (Ventricular Tachycardia < 1995)
• Data– Inclusions - All reports (regardless of nationality or administration)
– Exclusions - Duplicate reports/Reports < 1995 w/o TdP text– Systematic pharmacoepidemiological data extraction– PC SAS v6.12 (The SAS Institute™, Cary, NC)
• Search Results– 268 reports reviewed (- 112 exclusions)– 156 analyzed
Macrolide Antibiotics and TdPMacrolide Antibiotics and TdP
Macrolide Reports*, N [%]
Erythromycin 82 [53%]
Clarithromycin 56 [36%]
Azithromycin 18 [11%]
Dirithromycin 0
156
* 44 (28 %) IV: Azithromycin = 4, Erythromycin = 40
Demographic/Anthropometric DataDemographic/Anthropometric Data
Variable* Mean (SD) or Frequency [%]
Age (years) 61 (22)
Female 70%
Caucasian 60%
Weight (lbs.) 152 (32)
* Based upon N (%) of 156 reported: age = 93%, gender = 94%, race = 16%, weight = 26%
TdP Event CharacteristicsTdP Event Characteristics
Variable* Mean ( SD)
Baseline QT (msec) § 432 (50)
Event QT (msec) § 594 (80)
QT Change (msec) 172 (67)
Days to Event** 4 (3)
* N (%) reported: Baseline = 25%, Event = 36%, QT change = 24%, Days = 64%§ 59% of cases reported QTc ** 3 outliers (> 120 days) excluded
Fatalities = 14 events/156 reports [9%]Fatalities = 14 events/156 reports [9%]
Comorbid RisksComorbid Risks
Variable* Frequency [%]
Cardiac Disease 42%
Renal Disease 11%
Hepatic Disease 6%
Hypokalemia/ 17%Hypomagnesemia
* Frequency of concomitant risks based upon occurrence in AERS reports
Concomitant DrugsConcomitant Drugs
Variable Mean (SD) or Frequency [%]
Number of Drugs 4 (3), range: 0-15
Drug Interaction1 31%
QT Prolonging2,3 22%
1. Physician’s Desk Reference (2000)2. European Heart Journal 2000;21:1216-12313. Eur J Clin Pharmacol 2000;56:10-18
mutuallyexclusive
47%
31%
22%
Sole Suspect Drug
Contraindicated Drug Interaction
QT Prolonging Drug Co-Administration
Concomitant DrugsConcomitant Drugs
47%
31%
22%
Sole Suspect Drug
Contraindicated Drug Interaction
QT Prolonging Drug Co-Administration
Concomitant DrugsConcomitant Drugs
Cisapride78%
Terfenadine14%
Astemizole8%
Clarithromycin and Erythromycin TdP Reports -Clarithromycin and Erythromycin TdP Reports - Contraindicated DrugsContraindicated Drugs
N = 49:Clarithromycin = 21Erythromycin = 28
2. IMS HEALTH2. IMS HEALTH
MethodsMethods
• Data Source (1993-2000)– IMS Health’s National Prescription Audit Plus
– Retail, out patient prescriptions
– Oral formulations only
• Data Application– Descriptive representation (annual drug use)
– Comparison of relative estimated reporting rate ratios• reports (“numerator”) - domestic, oral-formulation, out-patient
• utilization (surrogate analytical population, “denominator”)
• cefuroxime used as control
Annual Macrolide Antibiotic Utilization
0
5,000,000
10,000,000
15,000,000
20,000,000
25,000,000
30,000,000
35,000,000
1993 1994 1995 1996 1997 1998 1999 2000
To
tal P
res
cri
pti
on
s *
Azithromycin Clarithromycin Erythromycin
Dirithromycin utilization on average < 500,000/year* IMS HEALTH’s National Prescription Audit Plus
Macrolides and TdP -Macrolides and TdP -Adjusted Report-Utilization Ratio*Adjusted Report-Utilization Ratio*
Drug Reports1 Utilization2 RatioRatio(N) (Millions) (Reports/1 million Rx)
Clarithromycin 16 90 0.18
Erythromycin 11 151 0.07
Azithromycin 7 124 0.060.06
Cefuroxime 1 42 0.020.02
* Ratio based upon domestic, oral-formulation, out-patient reports and 1993-2000 utilization
1. Spontaneous reports, 2. IMS HEALTH’s National Prescription Audit Plus
Summary and ConclusionsSummary and Conclusions
• Macrolide-associated TdP reports are from primarily older, female patients.
• Concomitant diseases/drugs are prevalent and potentially modifiable risks.
• Erythromycin overall accounts for most reports.
• Clarithromycin has the greatest reporting rate when considering domestic, out patient, oral cases & accounting for drug utilization.
• Clarithromycin and erythromycin TdP reporting rates are 9 and 3.5 times that of cefuroxime, respectively.
Postmarketing SummaryPostmarketing Summary
LimitationsLimitations
• Germane to spontaneous reporting systems
• Influence of biases
• Specificity of AERS data
• Inability to establish causation
Reporting Rate Estimates are not synonymous with Incidence Rates
AdvantagesAdvantages
• Systematic pharmacoepidemiological data extraction and evaluation
• Cost-efficient
• “Best Available Evidence”
• Detailed analysis of individual drugs
ConclusionsConclusions
• Telithromycin, the first of a new class of antimicrobials Telithromycin, the first of a new class of antimicrobials related to macrolides, interacts with cytochrome related to macrolides, interacts with cytochrome P450 metabolism and prolongs the QT interval.P450 metabolism and prolongs the QT interval.
• Recognition of the potential for Torsade de Pointes Recognition of the potential for Torsade de Pointes should clearly be acknowledged.should clearly be acknowledged.
• Monitoring of postmarketing data and development of Monitoring of postmarketing data and development of risk management strategies would be critical if the risk management strategies would be critical if the drug was marketed in the US.drug was marketed in the US.
http://www.fda.gov/medwatch/
1-800-FDA-1088
Supplemental Slides
AERS Reports: Quality and Causation*AERS Reports: Quality and Causation*
Variable Macrolides
Quality
Mean 3.2 (1.1)
Proportion “Average” 53% or greater
Causality
Mean 2.8 (1.0)
Proportion “Likely” or 44%“Strongly Suspect”
* See Data Definitions
macrolides
Macrolides and TdP:Macrolides and TdP:Adjusted Report-Utilization Ratio*Adjusted Report-Utilization Ratio*
Drug Reports1 Utilization2 RatioRatio(N) (Millions) (Reports/1 million Rx)
Clarithromycin 31 90 0.34
Erythromycin 17 151 0.11
Azithromycin 10 124 0.080.08
Cefuroxime 1 42 0.020.02
1. Spontaneous reports, 2. IMS™ HEALTH NPA Data
* Ratio based upon domestic, oral-formulation reports and 1993-2000 utilization
Cardiac DiseaseCardiac DiseaseVariable* Frequency [%]
Cardiomyopathy/ 23%
Congestive Heart Failure
Coronary Artery 17%
Disease
Valve Disease 10%
Atrial Fibrillation 9%
Pacemaker/Defibrillator 6%
* Frequency of concomitant risks based upon occurrence in AERS reports
macrolides
“Surrogate” Cardiac Events Reported*
Variable Frequency [%]
QT Prolongation 40%
Ventricular Tachycardia 36%
Syncope 28%
Cardiopulmonary Arrest/ 18%
Sudden Death
Ventricular Fibrillation 15%
Bradycardia 3%
Tachycardia 1%
* not exclusive, macrolides only
macrolides
Macrolide Antibiotics – Fatal Outcomes Reported (N=14)
Obs Sex Age Drug Route Base/EventQT
DI CardiacAbnormality
Hypo-K
1 F 40 Clarith Oral Cisapride2 F 89 Clarith Oral Y3 M 42 Clarith Oral4 F Eryth Y5 F 18 Eryth Oral Cisapride Y6 F 65 Eryth Oral Cisapride7 F 79 Eryth Oral8 F 78 Eryth IV Y9 F 90 Eryth Oral Cisapride Y
10 F 61 Eryth Oral/IV /380 Y11 F 83 Eryth Y12 Azith Oral13 F 70 Clarith Oral Y14 M 77 Clarith Oral 320/600 Y
Macrolides and TdP Reports (N)
0
5
10
15
20
25
30
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
Year
N
Ketoconazole -Terfenadine DI:JAMA
TerfenadineWithdrawal
Astemizole Withdrawal
CisaprideWithdrawal
TdPCodingData through 8/00
Macrolide & Quinolone Macrolide & Quinolone TdP ReportsTdP Reports
Macrolides77%
Quinolones23%
TdP ReportsTdP Reports
Macrolide = 156Quinolone = 46
Total 202
AERS Reports: Quality and Causation*AERS Reports: Quality and Causation*
Variable Macrolides Quinolones
Quality
Mean 3.2 (1.1) 3.3 (1.0)
Proportion “Average” 53% 54% or greater
Causality
Mean 2.8 (1.0) 2.8 (1.2)
Proportion “Likely” or 44% 39%“Strongly Suspect”
* See Data Definitions
Quinolone Antibiotics and TdPQuinolone Antibiotics and TdP
Quinolone Reports*, N [%]
Levofloxacin 12 [26.1]
Ciprofloxacin 10 [21.7]
Gatifloxacin 6 [13.0]
Norfloxacin, Sparfloxacin ** 5 [10.9]
Ofloxacin 3 [6.5]
Grepafloxacin 2 [4.3]
Lomefloxacin, Moxifloxacin, 1 [2.2] and Trovafloxacin **
47
* 10 (22%) IV: Levofloxacin = 5, Ciprofloxacin = 3, Gatifloxacin = 2 ** each
Demographic/Anthropometric DataDemographic/Anthropometric Data
Variable* MacrolidesQuinolones
Age (years) 61 (22) 72 (15)
Female 70% 67%
Caucasian 60% 67%
Weight (lbs.) 152 (32) 154 (27)
* N (%) reported: age = 93%, gender = 94%, race = 16%, weight = 26% age = 89%, gender = 93%, race = 7%, weight = 20%
Mean (SD) or Frequency [%]
TdP Event* CharacteristicsTdP Event* Characteristics
Variable Macrolide Quinolone
Baseline QT (msec) § 432 (50) 434 (44)
Event QT (msec) § 594 (80) 530 (151)
QT Change (msec) 172 (67) 112 (70)
Days to Event** 4 (3) 5 (8)
* N reported: Baseline = 25%, Event = 36%, QT change = 24%, Days = 64%Baseline = 24%, Event = 33%, QT change = 20%, Days = 72%
§ 59% & 67% of cases reported QTc ** 3 outliers excluded (> 120 days)
Fatalities Fatalities [14/156 = 9%] [14/156 = 9%] [6/46= 13%][6/46= 13%]
Comorbid RisksComorbid Risks
Variable Macrolides Quinolones
Cardiac Disease 42% 63%
Renal Disease 11% 7%
Hepatic Disease 6% 0
Hypokalemia/ 17% 15%Hypomagnesemia
* Frequency [%] of concomitant risks based upon occurrence in AERS reports
Concomitant DrugsConcomitant Drugs
Variable Macrolides Quinolones
Number of Drugs 4 (3), range: 0-15 4 (3), range: 0-10
Drug Interaction1 31%
QT Prolonging2,3 22% 24%
1. Physician’s Desk Reference (2000)2. European Heart Journal 2000;21:1216-12313. Eur J Clin Pharmacol 2000;56:10-18
Annual Quinolone Antibiotic Utilization
0
2,000,000
4,000,000
6,000,000
8,000,000
10,000,000
12,000,000
14,000,000
16,000,000
1993 1994 1995 1996 1997 1998 1999 2000
To
tal
Pre
sc
rip
tio
ns
*
Ciprofloxacin Levofloxacin Ofloxacin Trovafloxacin
Norfloxacin Lomefloxacin Grepafloxacin
Moxifloxacin = 844,000 andGatifloxacin = 1,797,000 in 2000* IMS HEALTH™ NPA Data
QT Prolonging Drugs / Drug Classes
Class DrugAntiarrhythmic Drugs Amiodarone, Bretylium, Dofetilide, Disopyramide,
Ibutilide, Procainamide, Quinidine, SotalolPsychiatric Drugs Amitriptyline, Chlorpromazine, Desipramine, Doxepin,
Droperidol, Fluphenazine, Haloperidol, Imipramine,Lithium, Maprotaline, Nortriptyline, Pimozide,Prochlorperazine, Sertindole, Thioridazine, Trifluoperazine
Antimicrobial Drugs Amantadine, Clarithromycin, Chloroquine, Cotrimoxazole,Erythromycin, Gatifloxacin, Grepafloxacin, Halofantrine,Ketoconazole, Levofloxacin, Pentamidine, Quinine,Sparfloxacin
Antihistamines Astemizole, Diphenhydramine, Hydroxazine, TerfenadineMiscellaneous Cisapride
Contraindicated Drug Interactions
Drug Labeled Contraindication / Drug InteractionAzithromycinClarithromycin Cisapride, Pimozide, TerfenadineDirithromycin TerfenadineErythromycin Astemizole, Cisapride, Terfenadine
Appendix B: Subjective Variables
1. “Quality of Report” Criteria
Quality – subjective evaluation based upon quantity and quality of information available,based upon the contents expected of a reasonable and prudent report.
1 = excellent (all drug, dates, QT, and relevant information available and understandable)2 = above “normal”3 = normal (the expected “norm,” – perhaps QT missing, but clear documentation of event)4 = suboptimal5 = poor (gross under-representation of data, perhaps simply “torsade de pointes” stated)
2. “Degree of Causation”
Causal – subjective evaluation based upon how likely you believe there is a causalrelationship
1 = strongly suspect (high degree of certainty [temporal, QT, no strong DI])2 = likely (EKG documentation, potentially due to DI, some other confounder)3 = possible (suspect drug with multiple comorbidities/confounders)4 = questionable (questionable data, other pharmacodynamic interactions)5 = doubtful (likely due to another etiology, strongly suspect causality)