Procainamide pharmacological effects

Concurrent administration of propafenone with digoxin, warfarin, propranolol, or metoprolol increases the serum concentrations of the latter four drugs. Cimetidine slightly increases the propafenone serum concentrations. Additive pharmacological effects can occur when lidocaine, procainamide, and quinidine are combined with propafenone. 

You are asked to treat a 55-year-old patient for continuing ventricular arrhythmias. The patient is receiving timolol drops for glaucoma, daily insulin injections for diabetes melUtus, and an ACE inhibitor for hypertension. You decide to use phenytoin instead of procainamide because of what pharmacological effect of procainamide ... 

Pharmacological Effects Procainamide is a blocker of open Na channels with an intermediate time constant of recovery from block. It also prolongs cardiac action potentials, probably by... 

Please note that it is the free acid or free base of a therapeutic agent that provides the pharmacological effect. For instance, when procainamide hydrochloride is administered to a patient, it is procainamide (free base) that is responsible for its pharmacological effect and not the hydrochloride part of the molecule. The pharmacokinetic parameters reported in the literature are obtained by measuring the free acid or base of a particular drug. 

Pharmacology Procainamide, a class lA antiarrhythmic, increases the effective refractory period of the atria, and to a lesser extent the bundle of His-Purkinje system and ventricles of the heart. 

The biotransformation of drugs may produce metabolites that are pharmacologically active. In such instances, the metabolite should also be measured because it is contributing to the effect of the drug on the patient. Primidone and procainamide are examples of such drugs. If the metabolite is inactive, it need not be measured, but steps should be taken to ensure that it does not interfere in the analytical process. 

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