Quinidine pharmacological effects

Other pharmacological effects - Clinical effects, in addition to antidepressant effects, include sedation, anticholinergic effects, mild peripheral vasodilator effects and possible quinidine-like actions. 

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. 

In pharmacodynamic interactions, the pharmacological effect of a drug is changed by the action of a second drug at a common receptor or bioactive site. For example, low-potency antipsychotics and tertiary amine TCAs have anticholinergic, antihistaminic, a-adrenergic antagonist, and quinidine-Kke effects. Therefore, concurrent administration of chlorpromazine and imipramine results in additive sedation, constipation, postural hypotension, and depression of cardiac conduction. 

More interesting is the pharmacology of ajmaline (37), which is available in large quantities as a by-product of the reserpine extraction. Detailed pharmacological studies seemed to be more than justified because reserpine did not possess all the pharmacological effects of crude Rauwolfia extracts. Ajmaline was compared with quinidine and studied clinically in cardiac arrhythmias,... 

Pharmacological Effects Quinidine (various generic preparations) blocks Na+ current and multiple cardiac K+ currents. It is an open-state blocker of Na+ channels, with a T in the inter-mediate (-3 seconds) range as a consequence, QRS duration increases modestly, usually by... 

Muir W W 1995 The haemodynamic effects of milrinone HCI In halothane anaesthetized horses. Equine Veterinary Journal Supplement 19 108-113 Muir W W, Mcguirk S M 1985 Pheirmacology and pharmacokinetics of drugs used to treat cardiac disease in horses. Veterinary Clinics of North America Equine Practice 1 335-352 Muir W W D, Mcguirk S 1987 Cardiovascular drugs. Their pharmacology and use In horses. Veterinary Clinics of North America Equine Practice 3 37-57 Muir W W D, Reed S M, Mcguirk S M 1990 Treatment of atrial fibrillation in horses by intravenous administration of quinidine. Journal of the American Veterinary Medical Association 197 1607-1610... 

This highly unsaturated indole alkaloid (CVI) which, like ajmaline, incorporates skeletal pattern XXI, has similar pharmacological properties to ajmaline, producing a brief hypotension [1136,1139-1142] which is due to a diminished cardiac output resulting from its quinidine-like action on the heart [1105, 1106, 1108-1110, 1143, 1144]. However, the unpredictable frequency of response and untoward side effects militate against clinical application of serpentine [1145] or its synthetic analogues [1146]. 

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