Usage
- Medical Conditions: Dimethicone is primarily used as a skin protectant to treat and prevent dry, rough, scaly, itchy skin, and minor skin irritations like diaper rash. It is also used to treat head lice. Orally administered dimethicone (simethicone) is used to relieve the symptoms of excess gas, such as bloating, belching, and feelings of pressure/discomfort in the stomach/abdomen.
- Pharmacological Classification: Skin protectant (topical), anti-flatulent (oral). Emollient.
- Mechanism of Action: Topically, dimethicone forms a protective barrier on the skin, reducing water loss and protecting against irritants. It also works against head lice by blocking their spiracles (breathing pores) causing suffocation. Orally, it works by decreasing the surface tension of gas bubbles in the gastrointestinal tract, allowing them to coalesce and be expelled more easily.
Alternate Names
- Alternate Names: Polydimethylsiloxane (PDMS), simethicone (oral form).
- Brand Names: There are many brand names depending on the formulation and country of origin. Examples include Mylicon, Gas-X, Phazyme (for simethicone), and many diaper rash creams and lotions. A healthcare professional can provide a list of local brand names.
How It Works
- Pharmacodynamics (Topical): Dimethicone creates a physical barrier on the skin that prevents moisture loss and protects from external irritants. It does not have any pharmacological activity on the skin itself. It does not get absorbed into the bloodstream. For head lice, dimethicone acts physically to suffocate the lice by blocking their breathing apparatus.
- Pharmacodynamics (Oral/Simethicone): Reduces the surface tension of gas bubbles allowing them to come together, which helps the body eliminate the gas by belching or flatulence.
- Pharmacokinetics (Topical): Minimally absorbed through intact skin.
- Pharmacokinetics (Oral/Simethicone): Not absorbed systemically from the gastrointestinal tract. It is excreted unchanged in the feces.
- Receptor Binding/Enzyme Inhibition/Neurotransmitter Modulation: Not applicable.
- Elimination Pathways (Topical): Not applicable due to negligible systemic absorption.
- Elimination Pathways (Oral/Simethicone): Primarily excreted in feces unchanged.
Dosage
Standard Dosage
Adults (Topical): Apply to affected area as needed.
Adults (Oral/Simethicone):
- Softgels: 120-180 mg after meals and at bedtime as needed.
- Chewable tablets: 40-125 mg after meals and at bedtime.
- Liquid drops: 40-80 mg as needed, four times a day after each meal and at bedtime, not to exceed 500 mg in 24 hours.
Children (Topical): Apply to affected area as needed.
Children (Oral/Simethicone):
- Under 2 years: 20 mg four times daily, not to exceed 240 mg daily
- Over 2 years: 40 mg four times daily, not to exceed 480 mg daily
Special Cases:
- Elderly Patients: Dose adjustment is not usually necessary but should be individualized based on factors such as renal and hepatic function.
- Patients with Renal Impairment: No dose adjustment is typically necessary.
- Patients with Hepatic Dysfunction: No dose adjustment is typically necessary.
- Patients with Comorbid Conditions: No specific dose adjustments are routinely required for other comorbid conditions, but clinical judgment should be applied in individual cases.
Clinical Use Cases
The use of dimethicone in intubation, surgical procedures, mechanical ventilation, ICU use, and emergency situations generally applies to its presence as a component in various medical devices and lubricants, rather than a specific drug administration for these scenarios.
Dosage Adjustments
No specific dosage adjustments based on renal/hepatic dysfunction, metabolic disorders, or genetic polymorphisms are usually needed, given its lack of systemic absorption.
Side Effects
Common Side Effects:
Topical: Mild skin irritation (e.g., itching, redness, rash) is possible at the application site.
Oral/Simethicone: Mild and transient gastrointestinal effects, such as nausea, diarrhea, constipation, and abdominal discomfort, have been reported infrequently.
Long-Term Effects: No long-term adverse effects have been reported with topical or oral dimethicone use.
Contraindications
- Absolute: Known hypersensitivity to dimethicone or any component of the formulation.
- Relative: Perforated bowel or suspected bowel obstruction (for oral/simethicone use).
Drug Interactions
- Topical Dimethicone: No significant drug interactions are known.
- Oral Dimethicone/Simethicone: May decrease the absorption of levothyroxine. Administration should be spaced at least 4 hours apart.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: Category C (Oral/Simethicone): Animal studies show potential adverse effects, but adequate studies in pregnant women are lacking. Should only be used if the potential benefits outweigh the risks. Topical use is generally considered safe during pregnancy.
- Breastfeeding: Topical: Not absorbed systemically, so considered compatible with breastfeeding. Oral/Simethicone: Limited information. While minimal absorption is expected, it’s advisable to exercise caution and consult a healthcare professional.
Drug Profile Summary
- Mechanism of Action (Topical): Forms a protective barrier, preventing moisture loss and irritation.
- Mechanism of Action (Oral/Simethicone): Reduces gas bubble surface tension, facilitating elimination.
- Side Effects: Generally well-tolerated. Mild skin irritation (topical) or gastrointestinal discomfort (oral) may rarely occur.
- Contraindications: Hypersensitivity. Perforated bowel or suspected bowel obstruction (oral/simethicone)
- Drug Interactions: May decrease levothyroxine absorption (oral/simethicone).
- Pregnancy & Breastfeeding: Topical: generally safe. Oral/Simethicone: Category C, limited information.
- Dosage: See above section for specific dosing guidelines.
- Monitoring Parameters: Not typically required.
Popular Combinations
Simethicone is often combined with antacids like aluminum hydroxide and magnesium hydroxide.
Precautions
- General Precautions: Ensure no hypersensitivity exists before use.
- Specific Populations: See “Pregnancy and Breastfeeding” section.
- Lifestyle Considerations: No specific lifestyle considerations are generally associated with topical or oral dimethicone use.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Dimethicone?
A: Refer to the detailed dosage section above, which provides information for adults, children, and specific formulations.
Q2: Is Dimethicone safe for use during pregnancy?
A: Topical application is generally considered safe. For oral/simethicone use, consult with a physician to evaluate potential risks and benefits. It is a pregnancy category C drug.
Q3: Can I use Dimethicone while breastfeeding?
A: Topical use is considered compatible with breastfeeding. Caution is advised with oral/simethicone due to limited safety information.
Q4: What are the potential side effects of Dimethicone?
A: Topical: Mild skin irritation. Oral/simethicone: Mild and transient gastrointestinal effects, such as nausea, diarrhea, constipation, and abdominal discomfort. Allergic reactions are rare but can occur with both topical and oral administration.
Q5: How does Dimethicone work for gas relief?
A: It reduces the surface tension of gas bubbles, allowing them to combine and be expelled from the digestive system more readily.
Q6: Are there any drug interactions with Dimethicone?
A: Oral/Simethicone may reduce the absorption of levothyroxine. Topical: No known significant interactions.
Q7: Can Dimethicone be used for both diaper rash and head lice?
A: Yes, although different formulations are used. Dimethicone is an ingredient in diaper rash creams, acting as a skin protectant. A 4% dimethicone lotion is used specifically for head lice, creating a suffocating environment for the lice.
Q8: How often should I apply topical Dimethicone?
A: Apply as needed, as per product label directions.
Q9: What should I do if I miss a dose of oral Simethicone?
A: Take the missed dose as soon as you remember. Do not double the dose to catch up.
