1. Clinical Overview
A fixed-dose combination (FDC) of a benzodiazepine (Diazepam) and an anticholinergic/antispasmodic (Dicyclomine). Primarily used for the short-term management of anxiety disorders and for the symptomatic relief of conditions involving smooth muscle spasm of the gastrointestinal tract, particularly when anxiety is a significant co-factor. The combination aims to provide both anxiolytic and antispasmodic effects, targeting the brain-gut axis. Its use is restricted due to the risk of dependence, sedation, and anticholinergic side effects.
| Onset | Duration | Bioavailability |
|---|---|---|
| Diazepam: Oral: 30-60 minutes. Dicyclomine: Oral: 1-2 hours. | Diazepam: Variable, dose-dependent; typically 6-12 hours for anxiolytic effect. Dicyclomine: Approximately 4-6 hours. | Diazepam: ~100% (oral). Dicyclomine: ~67% (oral). |
2. Mechanism of Action
The combination exerts synergistic effects on symptoms arising from anxiety-induced visceral hypersensitivity and smooth muscle spasm. Diazepam potentiates the effect of the inhibitory neurotransmitter GABA at the GABA-A receptor in the CNS, leading to anxiolysis, sedation, and muscle relaxation. Dicyclomine acts as a competitive antagonist at muscarinic (M1, M3) receptors on smooth muscle cells in the gastrointestinal tract, inhibiting acetylcholine-mediated contractions, thereby relieving spasm and associated pain.
3. Indications & Uses
- Short-term relief of severe anxiety disorders
- Symptomatic relief of irritable bowel syndrome (IBS) with predominant abdominal cramping and anxiety
- Symptomatic relief of other functional gastrointestinal disorders with spasm and anxiety component
4. Dosage & Administration
Adult Dosage: One tablet (Diazepam 2mg + Dicyclomine 20mg) two to three times daily. The lowest effective dose for the shortest duration should be used. Maximum: 3 tablets per day. Duration should not exceed 2-4 weeks without re-evaluation.
Administration: Take orally with or without food. Food may delay absorption but does not significantly affect overall bioavailability. Swallow whole with a glass of water. Do not crush or chew. Avoid taking immediately before bedtime if only daytime anxiety/spasm is targeted, due to drowsiness.
5. Side Effects
Common side effects may include:
- Drowsiness, sedation
- Dizziness, lightheadedness
- Dry mouth
- Blurred vision
- Constipation
- Fatigue
- Headache
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Alcohol, Opioids (e.g., Codeine, Tramadol) | Profound additive CNS and respiratory depression. Risk of coma and death. | Major |
| Other CNS Depressants (Antipsychotics, Antihistamines, Barbiturates) | Increased sedation, dizziness, impaired motor skills. | Major |
| CYP3A4 Inhibitors (Ketoconazole, Itraconazole, Clarithromycin, Ritonavir) | Increased Diazepam levels, prolonged sedation and side effects. | Major |
| CYP3A4 Inducers (Rifampicin, Carbamazepine, Phenytoin, St. John's Wort) | Decreased Diazepam levels, reduced efficacy. | Moderate |
| Other Anticholinergics (Amitriptyline, Oxybutynin, Trihexyphenidyl) | Additive anticholinergic side effects (dry mouth, constipation, urinary retention, confusion). | Major |
| Levodopa | Dicyclomine may reduce gastric motility and absorption of Levodopa. | Moderate |
| Digoxin | Anticholinergics may increase serum Digoxin levels by decreasing gut motility. | Moderate |
| Metoclopramide | Pharmacological antagonism; Dicyclomine opposes prokinetic effect. | Moderate |
7. Patient Counselling
- DO take exactly as prescribed by the doctor. Do not increase dose or frequency.
- DO inform all your doctors and dentists that you are taking this medicine.
- DO NOT stop this medicine abruptly if taken for more than 2 weeks; consult doctor for a tapering schedule.
- DO NOT consume alcohol in any form.
- DO NOT take with other sedative medicines without doctor's advice.
- DO use caution when getting up from sitting/lying position to avoid falls due to dizziness.
8. Toxicology & Storage
Overdose: Manifestations of combined CNS depression and anticholinergic toxicity: Severe drowsiness progressing to coma, confusion, hallucinations, paradoxical excitement, diminished reflexes, respiratory depression, apnea, hypotension, tachycardia, hyperthermia (hot dry skin), dilated pupils, urinary retention, seizures.
Storage: Store below 30°C, in a cool, dry place. Protect from light and moisture. Keep in the original blister pack or container. Keep out of reach of children and pets. Do not use after the expiry date printed on the pack. Dispose of unused tablets safely; do not flush. Return to pharmacy for disposal.