1. Clinical Overview
A fixed-dose combination (FDC) of an antispasmodic (Hyoscine butylbromide) and a non-steroidal anti-inflammatory drug (NSAID) of the fenamate class (Mefenamic Acid). It is primarily indicated for the symptomatic relief of pain associated with smooth muscle spasms, particularly in dysmenorrhea and gastrointestinal/renal colic. The combination provides dual action: Hyoscine butylbromide relieves the spasm, while Mefenamic Acid reduces the inflammatory pain and prostaglandin-mediated uterine contractions.
| Onset | Duration | Bioavailability |
|---|---|---|
| Hyoscine butylbromide: 15-30 minutes (oral). Mefenamic Acid: 30-60 minutes for analgesic effect. | Hyoscine butylbromide: 4-6 hours. Mefenamic Acid: 4-6 hours. | Hyoscine butylbromide: <10% (poor oral bioavailability due to quaternary ammonium structure). Mefenamic Acid: ~90%. |
2. Mechanism of Action
Hyoscine butylbromide is a competitive antagonist at muscarinic (M1, M2, M3) receptors in the smooth muscle of the gastrointestinal, biliary, and genitourinary tracts. It does not cross the blood-brain barrier, minimizing central side effects. Mefenamic Acid is a potent inhibitor of cyclooxygenase (COX-1 and COX-2) enzymes, thereby inhibiting the synthesis of prostaglandins, thromboxanes, and prostacyclins, which are mediators of pain, inflammation, and fever.
3. Indications & Uses
- Symptomatic relief of pain in primary dysmenorrhea (menstrual cramps)
- Symptomatic relief of pain associated with smooth muscle spasm: Renal colic, Biliary colic, Gastrointestinal colic
4. Dosage & Administration
Adult Dosage: One tablet (Hyoscine butylbromide 10mg + Mefenamic Acid 250mg) three times daily, or as directed by the physician. For dysmenorrhea, start at the onset of pain or menses.
Administration: Take with or after food to minimize gastrointestinal irritation. Swallow whole with a full glass of water. Do not crush or chew. Should be used on an 'as-needed' basis for acute painful spasms, not for continuous long-term therapy.
5. Side Effects
Common side effects may include:
- Dry mouth
- Blurred vision (transient)
- Drowsiness/sedation
- Nausea
- Epigastric discomfort/heartburn
- Constipation
- Dizziness
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Other NSAIDs (e.g., Ibuprofen, Diclofenac, Aspirin) | Increased risk of GI ulceration and bleeding, reduced antiplatelet effect of aspirin | Major |
| Anticoagulants (Warfarin, NOACs) | Increased risk of bleeding due to antiplatelet effect and protein binding displacement | Major |
| Oral Corticosteroids (e.g., Prednisolone) | Markedly increased risk of GI ulceration | Major |
| ACE Inhibitors (e.g., Ramipril), ARBs, Diuretics | Reduced antihypertensive efficacy, increased risk of renal impairment | Moderate |
| Lithium | Increased serum lithium levels and toxicity | Moderate |
| Methotrexate | Increased methotrexate toxicity (especially at high doses) | Moderate |
| Anticholinergics (e.g., Tricyclic antidepressants, Antipsychotics) | Additive anticholinergic side effects (dry mouth, urinary retention, constipation) | Moderate |
| Probenecid | Increased and prolonged plasma levels of Mefenamic Acid | Moderate |
| SSRIs (e.g., Sertraline, Fluoxetine) | Increased risk of upper GI bleeding | Moderate |
| Antacids | May reduce absorption of Mefenamic Acid | Minor |
7. Patient Counselling
- DO take with food or milk to avoid stomach upset.
- DO inform your doctor about all other medicines you are taking, including over-the-counter drugs and supplements.
- DO stay well hydrated while taking this medicine.
- DO stop the medication and consult your doctor if pain persists beyond 3 days for fever or 5 days for pain.
- DONT take more than the prescribed dose or for longer than directed.
- DONT crush or chew the tablet.
- DONT take this medicine if you are pregnant (especially last trimester) or planning pregnancy without consulting your doctor.
- DONT consume alcohol while on this medication.
8. Toxicology & Storage
Overdose: Hyoscine: Severe anticholinergic crisis (tachycardia, hyperthermia, flushed dry skin, dilated pupils, urinary retention, ileus, delirium, hallucinations, coma). Mefenamic Acid: Nausea, vomiting, epigastric pain, GI bleeding, headache, dizziness, tinnitus, metabolic acidosis, seizures, acute renal failure, respiratory depression.
Storage: Store below 30°C, in a cool, dry place, protected from light and moisture. Keep out of reach of children.