Study of an anti-arrhythmic agent, disopyramide, in delayed action form ('Ritmoforine' Retard)

A study was carried out in 10 patients with ventricular dysrhythmias to determine serum levels and effectiveness of treatment with a new delayed-action formulation of disopyramide. Patients received 1 tablet (322.5 mg disopyramide phosphate) twice daily and were monitored constantly. A therapeutically effective level of 3 mg/l was achieved in most cases after 24 hours and in 8 out of the 10 patients the levels remained reasonably stable during the 4 days of observation. It is suggested that adjustment of dosage is advisable in patients with renal dysfunction or left heart failure. Although the new formulation provided a good alternative to the standard preparation of disopyramide, which is usually given on a 4-times daily regimen, it is recommended that the standard capsules should be used during the first 24 hours of treatment to ensure that effective blood levels are achieved rapidly.