For typical adult acute spasm/colic dosing: 20 mg slow IV or IM. It may be repeated after 30 minutes if needed. Usual maximum is 100 mg in 24 hours. The IV dose should be given slowly. UK prescribing information

Some local product labels allow 20-40 mg per dose, so follow the specific ampoule insert and local protocol.

Important: use only by a trained clinician. Avoid or seek senior advice with suspected bowel obstruction/ileus, narrow-angle glaucoma, urinary retention/prostatic obstruction, myasthenia gravis, tachyarrhythmia, or unexplained severe abdominal pain. It can cause tachycardia, blurred vision, urinary retention, and rarely severe allergy.