Drotaverine is a potent, selective, and direct-acting antispasmodic agent belonging to the isoquinoline class. It is a papaverine derivative but lacks the opioid receptor activity of papaverine. It is widely used in the Indian clinical setting for the treatment of smooth muscle spasm associated with various gastrointestinal, genitourinary, and obstetric/gynecological conditions. It is particularly valued for its efficacy in biliary and renal colic, dysmenorrhea, and as an adjunct in irritable bowel syndrome (IBS). Its mechanism is distinct from anticholinergics, making it suitable for patients with glaucoma or prostatic hypertrophy.
Adult: 80 mg (one tablet) two to three times daily. Maximum: 240 mg/day (three tablets) in divided doses.
Note: Tablet to be swallowed whole with a glass of water, with or without food. Can be taken on an empty stomach for faster relief in acute colic. Do not crush or chew.
Drotaverine exerts its antispasmodic effect primarily through the selective inhibition of the enzyme phosphodiesterase IV (PDE-IV). This inhibition leads to an intracellular accumulation of cyclic adenosine monophosphate (cAMP) and, to a lesser extent, cyclic guanosine monophosphate (cGMP). The increased cAMP/cGMP levels inhibit the phosphorylation of myosin light-chain kinase (MLCK), leading to a decrease in intracellular calcium ion concentration. This results in the relaxation of smooth muscle fibers without affecting autonomic nervous system receptors.
Pregnancy: Category C (US FDA). Animal studies have shown fetotoxicity at high doses. Use during pregnancy, especially the first trimester, only if clearly needed and under strict medical supervision. Used in later trimesters for obstetric indications like threatened preterm labor.
Driving: May cause dizziness, lightheadedness, or blurred vision. Patients should not drive or operate machinery until they know how the drug affects them.
| Levodopa | Drotaverine may reduce the bioavailability and efficacy of levodopa. | Moderate |
| Other Antihypertensives (e.g., Beta-blockers, ACE inhibitors) | Additive hypotensive effect. | Moderate |
| Papaverine | Theoretical additive effect; avoid concurrent use. | Moderate |
| Strong CYP450 Inhibitors (e.g., Ketoconazole, Clarithromycin) | May increase drotaverine plasma levels, increasing risk of side effects. | Moderate |
| Morphine and other Opioid Analgesics | Synergistic antispasmodic and analgesic effect; used therapeutically in colic. | Mild (Therapeutic) |