Page 51 - RxExam's Naplex Theory Review Part-1

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Dose Special Notes

Clopidogrel 2. MI or PAD 3). The effectiveness of Clopidogrel (Plavix) is dependent on its
(Tablet) activation to an active metabolite by the cytochrome P450 (CYP)
75 mg once daily system, principally CYP2C19. Clopidogrel (Plavix) at recommended
orally, with or doses forms less of that metabolite and has a smaller effect on
without food. platelet function in patients who are CYP2C19 poor metabolizers.

4). Poor metabolizers with acute coronary syndrome or
undergoing percutaneous coronary intervention treated with
Clopidogrel (Plavix) at recommended doses exhibit higher
cardiovascular event rates than do patients with normal CYP2C19
function. Tests are available to identify a patient's CYP2C19
genotype; these tests can be used as an aid in determining
therapeutic strategy.

5). Omeprazole (Prilosec), a moderate CYP2C19 inhibitor, has been
shown to reduce the pharmacological activity of Clopidogrel
(Plavix) if given concomitantly or if given 12 hours apart. Consider
using another acid-reducing agent with less CYP2C19 inhibitory
activity. Pantoprazole (Protonix), a weak CYP2C19 inhibitor, had
less effect on the pharmacological activity of Clopidogrel (Plavix)
than Omeprazole.

6). Bleeding and thrombotic thrombocytopenic purpura are
commonly reported side effects of Clopidogrel (Plavix).

Dipyridamole 75-100 mg four 1). Dipyridamole (Persantine) inhibits the uptake of adenosine into
(Tablet) times daily as an platelets, endothelial cells and erythrocytes. This inhibition results
(Injection) adjunct to the usual in an increase in local concentrations of adenosine which acts on
warfarin therapy. the platelet A2-receptor thereby stimulating platelet adenylate
Please note that cyclase and increasing platelet cyclic-3',5'-adenosine
aspirin is not to be monophosphate (cAMP) levels. Via this mechanism, platelet
administered aggregation is inhibited in response to various stimuli such as
concomitantly with platelet activating factor (PAF), collagen and adenosine
coumarin diphosphate (ADP).
anticoagulants.
2). Dipyridamole (Persantine) is indicated as an adjunct to
coumarin anticoagulants in the prevention of postoperative
thromboembolic complications of cardiac valve replacement.

3). Dipyridamole may counteract the anticholinesterase effect of
cholinesterase inhibitors, thereby potentially aggravating
myasthenia gravis.

4). Bleeding, dizziness and abdominal distress are reported with
the therapy.

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