Quinidine polygalacturonate(Cardioquin) is formed by reacting quinidine andpolygalacturonic acid in a hydroalcoholic medium. It containsthe equivalent of approximately 60% quinidine. Thissalt is only slightly ionized and slightly soluble in water, butstudies have shown that although equivalent doses of quinidinesulfate give higher peak blood levels earlier, a moreuniform and sustained blood level is achieved with the polygalacturonatesalt.
In many patients, the local irritant action of quinidinesulfate in the gastrointestinal tract causes pain, nausea, vomiting,and especially diarrhea, often precluding oral use inadequate doses. Studies with the polygalacturonate saltyielded no evidence of gastrointestinal distress. It is availableas 275-mg tablets. Each tablet is the equivalent of200 mg of quinidine sulfate or 166 mg of free alkaloid.
