Extended-Release Tablets contain 0.375 mg of hyoscyamine sulfate in a formulation designed for oral b.i.d. These peripheral cholinergic receptors are present in the autonomic effector cells of the smooth muscle, the cardiac muscle, the sinoatrial node, the atrioventricular node, and the exocrine glands. At therapeutic doses, it is completely devoid of any action on autonomic ganglia.
Hyoscyamine sulfate is absorbed totally and completely by oral administration.
Hyoscyamine sulfate is partly hydrolyzed to tropic acid and tropine but the majority of the drug is excreted in the urine unchanged within the first 12 hours. Only traces of this drug are found in breast milk. Hyoscyamine sulfate passes the blood brain barrier and the placental barrier. Peak blood levels occur in approximately 4 hours and the apparent plasma elimination half-life is approximately 9 hours. Tablets may not completely disintegrate and may be excreted by some patients.