Pharmacogenetics in the Community Pharmacy: Thienopyridine Selection Post-Coronary Artery Stent Placement.

INTRODUCTION: Although antiplatelet therapy is a mainstay of post-percutaneous coronary intervention therapy, pharmacogenetic (PGt) considerations of therapy are often ignored despite related Food and Drug Administration warnings. Pharmacists are well situated to provide PGt guidance, and the community pharmacy is one setting where PGt testing, interpretation, and recommendations can take place to ensure optimal therapeutic outcomes. CASE REPORT: A 65-year-old man who had a myocardial infarction that was treated with PCI and stent placement was determined by a community pharmacist to be a candidate for PGt testing to ensure optimal antiplatelet therapy. The patient was seen in the pharmacy as a part of a medication therapy management encounter and underwent genetic testing. Results of the genetic testing indicated the need for modification of therapy. The community pharmacist interpreted the results and made the appropriate recommendation to the cardiologist who in turn modified antiplatelet therapy appropriately. CONCLUSION: This case describes the potential for collaboration between pharmacists and physicians to optimize antiplatelet therapy through PGt testing. Points of consideration for others looking to implement related PGt services are also discussed.

Elevated International Normalized Ratio associated with concurrent use of ophthalmic erythromycin and warfarin.

PURPOSE: The case of a patient whose International Normalized Ratio (INR) increased with concurrent use of ophthalmic erythromycin and warfarin is reported. SUMMARY: A 77-year-old Caucasian woman began therapy with warfarin for thromboembolism prophylaxis secondary to atrial fibrillation (target INR, 2-3). Warfarin was prescribed by her cardiologist, and care was established with clinical pharmacists in an anticoagulation clinic. She was receiving a weekly maintenance dosage of 14 mg. She had a history of atrial fibrillation, hyperlipidemia, osteoarthritis, hypothyroidism, coronary artery disease, myocardial infarction, congestive heart failure, and breast cancer. In addition to warfarin, the patient had been receiving alprazolam, carvedilol, furosemide, levothyroxine sodium, lisinopril, nitroglycerin, potassium chloride, propoxyphene hydrochloride-acetaminophen, simvastatin, and trazodone. After receiving warfarin at the same weekly dosage for over four months, the patient's ophthalmologist prescribed erythromycin ophthalmic ointment for chronic bacterial conjunctivitis. Three weeks later, her INR was found to be 8.5. A total of four warfarin doses were withheld, and her weekly maintenance dosage of warfarin was subsequently decreased to 12 mg. Five weeks later, her INR was 1.5, and it was determined that the erythromycin ophthalmic ointment had been discontinued five days prior. Her weekly maintenance dosage of warfarin was increased to 16 mg. Rechallenge with erythromycin five days before her next INR measurement resulted in an INR of 4.2. A new weekly maintenance dosage of 13 mg was established, and her subsequent INRs were within normal range. CONCLUSION: An increase in INR values was reported after initiation of ophthalmic erythromycin in a patient receiving warfarin and recurred upon rechallenge with ophthalmic erythromycin.

The Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) study: to what extent should the results be generalizable?

The Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) study investigated the use of clopidogrel in the treatment of acute coronary syndromes. Clopidogrel treatment led to an impressive 20% relative risk reduction in the composite outcome measure of vascular death, myocardial infarction, and stroke. Increased bleeding and greater requirements for blood transfusions were seen with clopidogrel. The addition of clopidogrel to aspirin represents a major advance in the treatment of acute coronary syndromes.

The CURE trial: using clopidogrel in acute coronary syndromes without ST-segment elevation.

In a large, randomized, placebo-controlled trial in centers that use a conservative approach to acute coronary syndromes, the antiplatelet drug clopidogrel (Plavix) decreased the rate of the combined end point of cardiovascular death, nonfatal myocardial infarction, or stroke by 20% in patients presenting with acute coronary syndromes without ST-segment elevation. The benefit was at the cost of an increase in bleeding, however. This strategy may need to be tailored in centers that use a more aggressive treatment strategy of early angiography and revascularization.