Medical Today

Pharmacology.

Codeine is 3-methoxymorphine, a phenanthrene opioid with very low affinity for opioid receptors. Its analgesic activity appears to result from conversion to morphine. Poor metabolizers of debrisoquine/sparteine (approximately 7% of the Caucasian population) cannot convert appreciable amounts of codeine to morphine or obtain analgesia from codeine but are still subject to the same adverse effects.

Administration and Adult Dosage.

PO, SC, or IM for analgesia 15-60 mg q 4-6 hr.

Pharmacology.
Cisplatin is a planar coordinate dichlorodiamino compound of platinum in the +II valence state. It is aquated in vivo to a positively charged species that can alkylate nucleophilic sites in DNA such as purine and pyrimidine bases. Its action is cell-cycle phase nonspecific.

Administration and Adult Dosage.
IV bolus or continuous infusion (usually with aggressive hydration) single doses of up to 120 mg/m2 have been used.
IV in the Einhorn testicular cancer regimen 20 mg/m2/day for 5 days.

Pharmacology.
Carboplatin is a more stable cyclobutane carboxylato derivative of cisplatin that is slowly activated to expose two DNA binding sites on the platinum II coordinate complex. The drug binds to DNA by both inter- and intrastrand cross-links in a fashion similar to, but more delayed than, that with cisplatin. It is more water soluble and commensurately less nephrotoxic than cisplatin. Action is cell-cycle phase nonspecific.

Pharmacology.
Aspirin is an analgesic, antipyretic, and anti-inflammatory agent. Anti-inflammatory properties are related to the inhibition of prostaglandin biosynthesis. Aspirin nonselectively inhibits cyclo-oxygenase-1 (COX-1), which is associated with GI and renal effects and inhibition of platelet aggregation, and cyclooxygenase-2 (COX-2), which is associated with the inflammatory response.
Unlike other NSAIDs, its antiplatelet effect is irreversible and permanent (because of transacetylation of platelet COX) for the life of the platelet (8-11 days). Salicylates without acetyl groups (eg, sodium salicylate) have essentially no antiplatelet effect but retain analgesic, antipyretic, and anti-inflammatory activities. Low dosages (1-2 g/day) decrease urate excretion; high dosages (>5 g/day) induce uricosuria.

Pharmacology.
Amiodarone is a type III antiarrhythmic that prolongs the effective refractory period of atrial and ventricular tissue by blocking potassium conductance. It decreases sinus rate and slows conduction through the AV node by beta-adrenergic blockade. Amiodarone also blocks sodium and calcium channels.

The antiarrhythmic actions can be caused by interruption of re-entrant substrate or abolition of premature beats that trigger re-entry.