7601 - Drug Interactions Pharm 560 2 October 2002 Philip D Hansten PharmD Professor School of Pharmacy University of Washington Drugs Removed from

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Unformatted text preview: Drug Interactions Pharm 560 2 October 2002 Philip D. Hansten, PharmD Professor, School of Pharmacy University of Washington Drugs Removed from the Market Due to Drug-Drug Interactions • Cerivastatin (Baycol): Rhabdomyolysis when combined with gemfibrozil • Terfenadine (Seldane): Ventricular arrhythmias with CYP3A4 inhibitors • Astemizole (Hismanal): Ventricular arrhythmias with CYP3A4 inhibitors • Cisapride (Propulsid): Ventricular arrhythmias with CYP3A4 inhibitors • Mebefradil (Posicor): Rhabdomyolysis when combined with simvastatin Hospital Admissions due to Drug Interactions in Elderly (France) • Prospective study of 1000 patients > 70 yo admitted to geriatric unit • 538 patients exposed to DDIs • 130 patients developed ADIs • Most common drugs involved were cardiovascular and psychotropic Doucet J et al. J Am Geriatr Soc. 1996;44:944-948. Severe Cimetidine Adverse Drug Interactions Are Rare • VA Hospital switched from ranitidine to cimetidine as cost-saving measure • Retrospective study of 4570 patients on cimetidine (10% got interacting drugs) • Only 4 patients had adverse interactions – 2 theophylline (nausea, vomiting, arrhythmia) – 1 procainamide (arrhythmia) – 1 warfarin (fatal intracerebral hemorrhage) Scott MA et al. Am J Health-Syst Pharm. 1999;56:1890-91. Uncommon Adverse Drug Interactions For an adverse drug interaction that occurs once in 1000 cases, one would have to study 3000 cases to have a 95% chance of observing the event. David Hume (1711-1776) • Scientific certainty is not possible using induction – “All swans are white.” • Absence of proof is not proof of absence – “Bigfoot does not exist.” – “Those drugs do not interact.” NO ADR OBSERVED Drug A + Drug B Assessing Drug Interactions Using Induction 25 Patients Usual Conclusion : This interaction is not clinically important. NO ADR OBSERVED Drug A + Drug B 25 Patients Correct Conclusion : Available information is insufficient to determine clinical importance. Assessing Drug Interactions Using Induction Prescriber’s Knowledge Computer Screening Pharmacist’s Knowledge Patient Risk Factors Patient Education Monitoring ADR Drug Interaction Defenses Hansten PD, Horn JR. Modified from: James Reason, Human Error, 1990 Drug Administration Pharmacogenetics Drug A + Drug B Defenses Prescriber’s Knowledge Computer Screening Pharmacist’s Knowledge Latent Failures Patient Risk Factors Patient Education Monitoring ADR A + B Drug Interactions: “When the Holes Line Up” Defenses Hansten PD, Horn JR. Modified from: James Reason, Human Error, 1990 Drug Administration Prescriber’s Knowledge...
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This note was uploaded on 02/23/2012 for the course PHARM 290 taught by Professor Staff during the Fall '10 term at Rutgers.

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7601 - Drug Interactions Pharm 560 2 October 2002 Philip D Hansten PharmD Professor School of Pharmacy University of Washington Drugs Removed from

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