Robert J. Holt

Familial Warfarin Resistance

Warfarin, a coumarin anticoagulant, acts by interfering with the hepatic synthesis of the vitamin-K-dependent clotting factors. It is used clinically in the treatment or prophylaxis of venous thrombosis and embolisms. Resistance to the effects of the coumarin and indanedione anticoagulants has been reported in rats and man, but its incidence has been defined as extremely rare. Resistance has been described as relative, acquired, or hereditary. The first well-documented case was also the first report to identify a genetic basis for this resistance. Since that time, there has been only one other study that strengthened the evidence for a hereditary transmission, and only a few other reports have suggested hereditary influence as a reason for coumarin resistance. In this report, a patient who presented with a familial-type warfarin resistance is described. A discussion of previous reports and possible mechanisms for nonfamilial warfarin resistance is also included.

Hyperglycemia associated with Propranolol and Chlorpropamide Coadministration

A 59-year-old patient with acute pancreatitis is described, whose treatment was complicated by concomitant diabetes mellitus and arterial hypertension. He received propranolol and insulin without subsequent problems; however, when the insulin was changed to chlorpropamide, a significant increase in blood sugar occurred. It was postulated that this increase in blood sugar was due to an antagonistic action of propranolol at the pancreatic level which interfered with the action of chlorpropamide.

Comment: Zolpidem: Distinct from Triazolam?:

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Uncharacteristic Cutaneous Reactions Induced by Quinidine

Two patients who presented with unusual cutaneous reactions attributed to quinidine are described. One had a diffuse nonpruritic macular rash, and the other had a localized pruritis without cutaneous manifestations. Both resolved upon de-challenge with quinidine. Disopyramide phosphate was substituted for quinidine in both cases, without subsequent problems.