Introduction
Simethicone is an over-the-counter antiflatulent medication used to relieve symptoms associated with excess gas in the gastrointestinal tract. It is classified as a surfactant that alters the surface tension of gas bubbles, facilitating their coalescence and elimination. Unlike many pharmacological agents, simethicone is not systemically absorbed and acts locally within the GI tract.
Mechanism of Action
Simethicone works by reducing the surface tension of gas bubbles in the gastrointestinal tract. This action causes smaller bubbles to coalesce into larger bubbles, which are more easily expelled from the body through belching or flatus. The drug is physiologically inert and does not affect gastric acid secretion or intestinal motility.
Indications
- Symptomatic relief of flatulence
- Postoperative gas pain (especially following abdominal surgery)
- Functional gastric bloating
- As an adjunct in diagnostic procedures (endoscopy, radiography) to improve visualization by reducing gas bubbles
- Infant colic (though evidence is limited)
Dosage and Administration
Adults: 40-125 mg after meals and at bedtime, not to exceed 500 mg daily Children 2-12 years: 40 mg up to four times daily Infants: 20 mg after meals and at bedtime (typically administered as drops) Available formulations: Chewable tablets, softgel capsules, liquid drops, and liquid suspensions Special populations:- Geriatric: No dosage adjustment required
- Renal/hepatic impairment: No dosage adjustment needed (not systemically absorbed)
- Pregnancy: Category C - generally considered safe due to lack of systemic absorption
Pharmacokinetics
Absorption: Not absorbed from the gastrointestinal tract Distribution: Acts locally within the GI lumen Metabolism: Not metabolized Elimination: Excreted unchanged in feces Half-life: Not applicable (local action only)Contraindications
- Hypersensitivity to simethicone or any component of the formulation
- Intestinal obstruction or perforation (relative contraindication)
Warnings and Precautions
- Symptoms persisting beyond 1 week warrant medical evaluation
- Not for use in children under 2 years without medical supervision
- Use caution in patients with suspected bowel obstruction
- Does not treat underlying gastrointestinal disorders
Drug Interactions
No clinically significant drug interactions have been documented due to:
- Lack of systemic absorption
- No effect on cytochrome P450 enzymes
- No protein binding
- No alteration of gastrointestinal pH
However, may theoretically affect absorption of other medications by altering gastrointestinal surface tension (clinical significance unknown).
Adverse Effects
Simethicone is generally well-tolerated with an excellent safety profile:
Common: None reported Rare: Mild gastrointestinal discomfort (theoretical) Serious: No serious adverse effects reported in medical literatureMonitoring Parameters
- Symptom relief and resolution of gas-related discomfort
- No laboratory monitoring required
- Assessment of need for continued therapy beyond 1 week
- Evaluation for underlying gastrointestinal pathology if symptoms persist
Patient Education
- Take after meals and at bedtime for optimal effect
- Chew tablets thoroughly before swallowing
- Shake liquid formulations well before use
- Consult healthcare provider if symptoms persist beyond 1 week
- Does not prevent gas formation—considers dietary modifications if gas is recurrent
- Store at room temperature away from moisture
- Keep out of reach of children
References
1. Pharmaceuticals MHPD. Product Monograph: Simethicone. Health Canada; 2021. 2. McPherson ML, et al. American Society of Health-System Pharmacists. AHFS Drug Information; 2023. 3. Lexicomp Online. Simethicone: Drug Information. Wolters Kluwer Clinical Drug Information; 2023. 4. Traverso LW, et al. Oral simethicone for the treatment of postoperative abdominal discomfort. Am J Surg. 1998;176(5):462-465. 5. Drugs.com. Simethicone Professional Monograph. 2023. 6. Micromedex Solutions. Simethicone Drug Information. IBM Watson Health; 2023. 7. National Library of Medicine. Simethicone - Drug Information. DailyMed; 2023.