Papaverine is a non-opiate benzylisoquinoline alkaloid derived from the opium poppy (Papaver somniferum). It is a direct-acting smooth muscle relaxant, primarily used as a vasodilator. In the Indian clinical context, it is most commonly employed for the treatment of visceral spasm, peripheral vascular diseases, and as an adjunct in diagnostic procedures. Its injectable form (30mg/ml) is used for intramuscular, intravenous, or intracavernosal administration.
Adult: IM/IV: 30-120 mg, repeated every 3 hours as needed. Usual dose is 30-60 mg. Intracavernosal: Start with 7.5-30 mg (0.25-1 ml of 30mg/ml solution). Dose must be titrated under medical supervision.
Note: For IV use: Dilute in Normal Saline or 5% Dextrose and administer slowly over 1-2 minutes. Rapid IV injection can cause arrhythmias and profound hypotension. For IM use: Inject deep into a large muscle mass. For Intracavernosal: Use a tuberculin syringe, administer at the lateral base of the penis, rotate sites, and apply pressure after injection. Patient must remain under observation for priapism.
Papaverine is a non-specific phosphodiesterase (PDE) inhibitor. It increases intracellular concentrations of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) by inhibiting their breakdown. Elevated cAMP/cGMP leads to activation of protein kinase A (PKA) and protein kinase G (PKG), which in turn phosphorylate and inhibit myosin light-chain kinase (MLCK). This results in decreased intracellular calcium levels and smooth muscle relaxation independent of innervation.
Pregnancy: Category C: Animal reproduction studies have shown adverse effects. There are no adequate and well-controlled studies in humans. Use only if potential benefit justifies potential risk to the fetus.
Driving: May cause dizziness, drowsiness, or blurred vision. Patients should be cautioned against driving or operating machinery until they know how the drug affects them.
| Levodopa | Papaverine may antagonize the anti-parkinsonian effect of levodopa. | Major |
| Antihypertensives (e.g., Beta-blockers, ACE inhibitors) | Additive hypotensive effect. | Moderate |
| Sildenafil, Tadalafil, Vardenafil | Concomitant use with intracavernosal papaverine can cause profound hypotension and priapism. | Major |
| CYP2C9 Inhibitors (e.g., Fluconazole, Amiodarone) | May increase papaverine plasma concentrations, increasing risk of toxicity. | Moderate |
| Hepatotoxic drugs (e.g., Paracetamol high-dose, Statins) | Increased risk of liver injury. | Moderate |
Same composition (Papaverine (30mg/ml)), different brands: