Scopolamine Butyl Bromide

Products

Scopolamine butylbromide is available worldwide in the form of dragées, suppositories, and as a solution for injection. It has been commercially available in Germany and in many countries since 1952 (Buscopan, Boehringer Ingelheim) in the form of the dragées and suppositories even without a doctor’s prescription. In some countries, a combination with the analgesic paracetamol is also sold (Germany: Buscopan plus).

Structure and properties

Scopolamine butylbromide or -butylscopolamine (C17H22BrNO4 – 3H2O, Mr = 438.3 g/mol) exists as a white powder or in the form of colorless crystals. It is readily soluble in water. Scopolamine butyl bromide is a -butyl derivative of scopolamine, a tropane alkaloid naturally occurring in solanaceous plants such as datura.

Effects

Scopolamine butylbromide (ATC A03BB01) is anticholinergic and antispasmodic to smooth muscle of the digestive tract, genitourinary tract, and biliary tract. It binds with high affinity to muscarinic receptors and blocks the effects of acetylcholine and the parasympathetic nervous system (muscarinic receptor antagonist). Scopolamine butyl bromide, unlike scopolamine, is a quaternary nitrogen compound, which translates into altered pharmacokinetic properties. Because of its positive charge, it is poorly absorbed, has low bioavailability, and does not enter the brain. As a result, the risk of systemic and central anticholinergic side effects is low. However, this is true only for oral and rectal administration and not for parenteral administration. Clinical efficacy has been studied in numerous older and modern clinical trials.

Indications

Spasms and motility disorders of the digestive tract, biliary and urinary tracts, smooth muscle, menstrual cramps, as a solution for injection also in diagnostic procedures (e.g., x-rays, endoscopies) and for spasms of soft tissues during childbirth. Scopolamine butylbromide is used off-label in other indications (for review, see Tytgat, 2007, 2008).

Dosage

According to the package insert. The usual single oral dose for adults and schoolchildren is 10 to 20 mg, and the maximum daily dose is 100 mg.

Abuse

Because overdose results in increased anticholinergic effects, scopolamine butylbromide can theoretically be abused as a narcotic and hallucinogen, like some nightshade drugs. According to studies, however, no central effects occur even at a daily dose of 600 mg (60 tablets of 10 mg each), which is why scopolamine butylbromide appears unsuitable as a narcotic. We do not know whether it crosses the bloodbrain barrier at a very high dose. Because of the health risks, overdose is strongly discouraged.

Contraindications

Scopolamine butylbromide is contraindicated in hypersensitivity, myasthenia gravis, and megacolon. It should be used with caution in narrow-angle glaucoma, intestinal and urinary tract obstruction, benign prostatic enlargement with urinary retention, cardiac arrhythmias and rapid heartbeat (tachycardia), and should not be used with parenteral administration. Refer to the drug label for complete precautions.

Interactions

Because scopolamine butylbromide is anticholinergic, it may potentiate the adverse effects of other anticholinergic agents, such as antidepressants, neuroleptics, or antihistamines. Metoclopramide may attenuate the effects of scopolamine butylbromide. Interactions are further possible with beta-agonists and digoxin.

Adverse effects

Common possible adverse effects with oral or rectal administration include local digestive side effects such as dry mouth, constipation, diarrhea, and urinary retention and rapid pulse (tachycardia). Occasionally, skin reactions may occur. In contrast, hypersensitivity reactions, fatigue, headache, severe allergic reactions, difficulty breathing, and sweat secretion disorders are rare to very rare. Although systemic and central anticholinergic side effects are reported to be rare, they must be considered when evaluating patients. More adverse effects occur with injection because the substance enters the bloodstream directly. However, the bloodbrain barrier is not crossed anyway.