Monosulfiram

Approved Indications:

• Scabies: Topical treatment of scabies infestation caused by Sarcoptes scabiei.
• Pediculosis (Head Lice): Treatment of pediculosis capitis (infestation with head lice).
• Fungal skin infections: Mild cases of tinea versicolor or other superficial fungal infections as adjunctive therapy (topical use).
• Dermatological disinfectant: Occasionally used for pre-operative skin cleansing or minor skin disinfection.

Off-label (Clinically Accepted) Uses:

• Secondary infected scabies lesions as an adjunct due to its antiseptic and antiparasitic effects.
• Crusted/Norwegian scabies as part of combination therapy with oral antiparasitics under strict supervision.

Adults:

• Scabies:
• Topical application of 25% Monosulfiram solution or emulsion over the entire body from neck down.
• Leave on for 12–24 hours; then bathe thoroughly.
• Usually one application is sufficient; may repeat after 5–7 days if needed.
• Pediculosis (head lice):
• Apply 2–5% lotion to scalp and hair thoroughly.
• Leave on for 30–60 minutes, then rinse and comb to remove lice/nits.
• Repeat application after 7 days if infestation persists.

Pediatrics:

• Scabies and lice (children >2 years):
• Apply lower concentrations (5–10% for scabies or 1–2% for lice) to affected areas.
• Avoid contact with eyes, mucous membranes, or broken skin.
• Use only under physician supervision.
• Infants (<2 years):
• Safety not established. Use not recommended due to risk of absorption and toxicity.

Elderly:

• Same as adult dosing.
• Use with caution in frail or thin-skinned patients due to increased risk of irritation.

Hepatic or Renal Impairment:

• Topical use unlikely to require dosage modification.
• Avoid excessive or prolonged application to prevent systemic absorption, especially in patients with skin barrier damage.

Route of Administration:

• Topical only. Not for oral or systemic use.
• Apply to clean, dry, unbroken skin only.

Monosulfiram is a topical scabicide and pediculicide with antiparasitic and antifungal activity. It interferes with the energy metabolism and neural transmission of parasites such as scabies mites and lice, causing paralysis and death. Additionally, it acts as a local antiseptic, disrupting microbial membranes and inhibiting their growth. Though the exact mechanism in humans is not fully understood, its sulfur component and disulfide linkage are thought to play roles in inhibiting parasite respiration and cell wall stability.

• Absorption: Minimal systemic absorption through intact skin; enhanced if applied to broken or inflamed skin.
• Distribution: Not systemically distributed under normal conditions.
• Metabolism: Not significantly metabolized when used topically. If absorbed, likely hepatic metabolism similar to disulfiram.
• Excretion: Traces, if absorbed, are eliminated renally.
• Onset of Action: Within hours of application; antiparasitic effects observed within 24 hours.

• Pregnancy:
  No formal FDA pregnancy category. Safety during pregnancy has not been established. Avoid during the first trimester unless clearly indicated. Topical use on intact skin may be considered if benefit outweighs risk.
• Lactation:
  Unknown whether it is excreted into breast milk. Avoid applying to areas where infant may come into contact (e.g., chest). Caution advised if used during breastfeeding.

• Primary Class: Topical Antiparasitic Agent
• Subclass: Scabicide and Pediculicide (Sulfur-based disulfide derivative)

• Known hypersensitivity to Monosulfiram or any excipients.
• Broken, ulcerated, or inflamed skin.
• Application to mucosal surfaces (eyes, mouth, genitals).
• History of alcohol use during or within 12 hours of application (due to disulfiram-like reaction).
• Infants under 2 years of age.

• Avoid alcohol use (topically or systemically) during and for at least 12 hours after application to prevent disulfiram-like reaction (flushing, nausea, vomiting, hypotension).
• Do not apply to mucous membranes, face, or broken skin, which may lead to irritation or systemic absorption.
• Use with caution in pediatric and geriatric populations, especially those with fragile or damaged skin.
• Stop treatment immediately if signs of severe irritation, dermatitis, or allergic reaction occur.
• Avoid prolonged or repeated use.

Common (localized):

• Skin irritation (burning, redness, itching)
• Mild contact dermatitis
• Dry or peeling skin

Less Common:

• Allergic contact dermatitis
• Stinging or rash upon application
• Foul odor or discoloration of skin

Rare but Serious:

• Disulfiram-like reaction (flushing, headache, nausea) if combined with alcohol use
• Systemic toxicity if used excessively or on broken skin
• Neurotoxicity (theoretical, with excessive or accidental ingestion)

Severity & Onset:

• Effects are generally mild and localized, occurring within minutes to hours of application.

• Alcohol: Both topical and oral alcohol can trigger disulfiram-like reaction including flushing, tachycardia, nausea, and hypotension.
• Other topical irritants: Concurrent use with harsh soaps, astringents, or exfoliants may increase irritation risk.
• Disulfiram or related drugs: Additive neurotoxicity possible if absorbed systemically.

No known CYP450 system interactions due to minimal systemic absorption.

• No major changes in regulatory guidance or labeling globally.
• Still used in some regions where cost-effective scabicide options are preferred.
• Safer alternatives (e.g., permethrin) may be preferred in pediatric or immunocompromised patients.
• No recent black box warnings or global safety alerts.

• Temperature: Store at 20°C to 25°C (room temperature).
• Humidity & Light: Protect from light and excessive moisture. Keep tightly sealed.
• Handling Precautions:
• Do not refrigerate or freeze.
• Shake well before use if suspension or lotion.
• Keep away from heat, flame, or alcohol-based products.
• Shelf-life: Follow manufacturer's labeled expiry; discard if discolored or if odor becomes strong.