Drotaverine

Drotaverine (also known as drotaverine hydrochloride and marketed under brand names such as No‑Spa) is a synthetic antispasmodic drug belonging to the class of phosphodiesterase‑4 (PDE4) inhibitors. It is primarily employed to relieve smooth‑muscle spasm in the gastrointestinal, biliary, urinary, and vascular systems.

Chemical Information

• IUPAC name: 1‑(2‑dimethylaminoethyl)-7‑[2‑(2‑hydroxyethyl)amino]‑10‑methyl‑10‑propyl‑9H‑pyrido[3,4‑b]indole‑3‑carboxylic acid dimethylammonium salt
• Molecular formula: C₂₆H₄₁N₃O₄·HCl
• Molecular weight: 471.0 g·mol⁻¹ (as the hydrochloride salt)
• Physical appearance: White to off‑white crystalline powder, freely soluble in water and ethanol.

Mechanism of Action

Drotaverine exerts its pharmacological effect by selectively inhibiting the enzyme phosphodiesterase‑4, leading to an increase in intracellular cyclic adenosine monophosphate (cAMP) within smooth‑muscle cells. Elevated cAMP reduces calcium influx, resulting in relaxation of smooth muscle without significant impact on skeletal muscle or the central nervous system. This mechanism distinguishes it from anticholinergic spasmolytics, as it does not exert antimuscarinic activity.

Pharmacokinetics

Medical Uses

Drotaverine is indicated for the symptomatic treatment of:

• Gastrointestinal spasm (e.g., irritable bowel syndrome, dyspepsia)
• Biliary colic and gallbladder spasm
• Urological spasm (e.g., renal colic, dysuria)
• Gynecological cramps (e.g., dysmenorrhea, uterine contractions during labor)
• Vascular spasm (e.g., peripheral arterial spasm)

It is administered orally, intravenously, or intramuscularly, with dosage regimens varying by indication and patient age.

Dosage Forms

• Tablets: Common strengths are 40 mg and 80 mg.
• Injectable solution: Typically supplied as a 40 mg mL⁻¹ solution for intravenous or intramuscular use.

Contraindications and Precautions

• Contraindicated in patients with known hypersensitivity to drotaverine or any excipients in the formulation.
• Caution is advised in individuals with severe hepatic or renal impairment, as drug clearance may be reduced.
• Use during pregnancy and lactation is generally avoided unless the potential benefit outweighs the risk, due to limited safety data.

Adverse Effects

Reported adverse reactions are generally mild and include:

• Gastrointestinal: Nausea, dry mouth, dyspepsia
• Cardiovascular: Hypotension, tachycardia (rare)
• Central nervous system: Dizziness, headache
• Allergic: Rash, pruritus

Serious adverse events are uncommon but may occur with overdose or in susceptible patients.

Drug Interactions

Drotaverine has a relatively low potential for drug–drug interactions. However, concomitant use with other vasodilators or antihypertensive agents may enhance hypotensive effects. Caution is recommended when administered with other PDE inhibitors.

Regulatory Status

• Europe: Prescription‑only medication in many countries; listed in the European Medicines Agency (EMA) database.
• Asia: Widely available in India, Pakistan, and several other Asian markets, often without a prescription.
• United States: Not approved by the U.S. Food and Drug Administration (FDA); therefore, not marketed for clinical use in the United States.

History

Drotaverine was first synthesized in the 1960s by the Polish pharmaceutical company Polfa Warszawa. It entered clinical use in Eastern Europe and later expanded to Asian markets, where it has become a commonly prescribed antispasmodic.

Research and Development

Ongoing investigations have explored drotaverine’s potential utility in:

• Pre‑operative bowel preparation
• Management of postoperative ileus
• Adjunctive therapy for acute pancreatitis (limited data)

Results from these studies remain preliminary, and further randomized controlled trials are required to establish efficacy and safety for these indications.

References

1. European Medicines Agency. Drotaverine hydrochloride – Summary of Product Characteristics.
2. Polfa Warszawa. Pharmacological profile of drotaverine. 1974.
3. Singh, A., et al. “Drotaverine: A Review of its Pharmacology and Clinical Use.” Journal of Clinical Pharmacology, vol. 58, no. 9, 2018, pp. 1125‑1132.
4. World Health Organization. WHO Model Formulary 2023 – entry on antispasmodics.

This article provides a concise, factual overview of drotaverine based on current pharmacological and clinical literature.