Benzyl Alcohol

Usage

• Benzyl alcohol is prescribed for the treatment of head lice infestations. It is also used as a preservative in various medications, a local anesthetic for pain relief by numbing the skin, a solvent in pharmaceutical formulations and cosmetics.
• Pharmacological Classification: Antiparasitic (for head lice), local anesthetic, antiseptic, preservative.
• Mechanism of Action: Benzyl alcohol acts on lice by disrupting their spiracles, which are small openings they use for breathing. This leads to asphyxiation and death of the lice. As a local anesthetic, it blocks nerve conduction, reducing pain sensation. It also functions as a bacteriostatic preservative, inhibiting the growth of bacteria in pharmaceutical preparations.

Alternate Names

• Phenylmethanol
• Phenylcarbinol
• Benzenemethanol
• Brand Names: Ulesfia, Zilactin, AverTeaX

How It Works

• Pharmacodynamics: Benzyl alcohol acts as a neurotoxin to lice, causing their death. It produces local anesthesia by blocking nerve conduction, thereby reducing pain sensation at the application site. As a preservative, it inhibits bacterial growth.
• Pharmacokinetics: Topical application results in minimal systemic absorption. When administered intravenously, it is rapidly metabolized in the liver to benzoic acid, which is conjugated with glycine to form hippuric acid and then excreted in the urine.
• Mode of Action: In lice, benzyl alcohol disrupts spiracles, leading to asphyxiation. As a local anesthetic, it non-selectively blocks voltage-gated sodium channels, preventing nerve impulse transmission. Its antiseptic action results from its ability to denature proteins and disrupt cell membranes of microorganisms.
• Elimination Pathways: Primarily hepatic metabolism followed by renal excretion of hippuric acid.

Dosage

Standard Dosage

Adults:

• Head Lice: Apply 5% benzyl alcohol lotion to dry hair and scalp, ensuring complete saturation. Leave on for 10 minutes, then rinse thoroughly with water. Repeat treatment after 7 days.
• Local Anesthetic: Apply a thin layer to the affected area as directed by a healthcare provider.

Children:

• Head Lice: For children 6 months and older, follow the adult dosage. Do not use in infants under 6 months of age.
• Pediatric Safety Considerations: Avoid contact with eyes and mucous membranes. Monitor for signs of skin irritation or allergic reactions.

Special Cases:

• Elderly Patients: Limited data is available on the safety and efficacy in patients over 60 years old for head lice treatment. For other uses, dose adjustments may be necessary based on organ function.
• Patients with Renal Impairment: Caution is advised in patients with severe renal impairment if using benzyl alcohol in injectable medications due to a risk of accumulation. Dose adjustments may be required.
• Patients with Hepatic Dysfunction: Use with caution in patients with hepatic impairment as metabolism may be affected. Dose adjustments may be required.
• Patients with Comorbid Conditions: Assess patient-specific factors and consider dose modifications accordingly.

Clinical Use Cases

• For intravenous preparations containing benzyl alcohol as a preservative, the dosage varies depending on the specific medication. It’s crucial to avoid exceeding the recommended daily limit of benzyl alcohol from all sources, particularly in neonates and young children.
• Other Clinical Use Cases: Dose and administration depend on the specific formulation and clinical indication (e.g., preservative, anesthetic).

Dosage Adjustments

• Dose adjustments may be required for patients with renal or hepatic impairment, as well as for other specific patient populations based on individual needs and tolerance.

Side Effects

Common Side Effects

• Mild skin irritation or redness
• Itching or dryness at the application site
• Temporary numbness or tingling at the application site

Rare but Serious Side Effects

• Allergic reactions (rash, hives, swelling, difficulty breathing)
• Neurotoxicity in infants (high doses, especially intravenous, can cause respiratory distress or neurological symptoms – rare)

Long-Term Effects

• No significant long-term adverse effects have been reported with topical use.

Adverse Drug Reactions (ADR)

• Severe allergic reactions (anaphylaxis)
• “Gasping syndrome” in neonates (rare but potentially fatal; characterized by metabolic acidosis, respiratory distress, and cardiovascular collapse)

Contraindications

• Hypersensitivity to benzyl alcohol
• Premature infants and neonates (for intravenous formulations containing benzyl alcohol as a preservative)
• Infants under 6 months of age (for head lice treatment)

Drug Interactions

• Topical application: Minimal systemic absorption reduces the likelihood of significant drug interactions. Concurrent use with other topical products may increase the risk of skin irritation.
• Intravenous formulations: Avoid use in neonates and preterm infants due to potential toxicity. Monitor for potential additive effects when administered with other CNS depressants.
• No significant CYP450 interactions have been reported.

Pregnancy and Breastfeeding

• Pregnancy Safety Category: C (animal studies show adverse effects, but human data is limited). Use only if potential benefit justifies potential risk to the fetus.
• Fetal Risks: Animal studies have shown potential for decreased fetal weight and maternal toxicity at high doses. Limited data is available for human pregnancy.
• Breastfeeding: It is unknown whether benzyl alcohol is excreted in breast milk. Exercise caution when using in breastfeeding mothers. Consider alternate safer options when feasible.

Drug Profile Summary

• Mechanism of Action: Disrupts spiracles in lice, blocks nerve conduction for local anesthesia, and inhibits bacterial growth as a preservative.
• Side Effects: Mild skin irritation, itching, dryness. Rare but serious: allergic reactions, gasping syndrome in neonates.
• Contraindications: Hypersensitivity, premature infants and neonates (IV), infants under 6 months (head lice).
• Drug Interactions: Minimal with topical use. Additive CNS depression with IV use with other CNS depressants.
• Pregnancy & Breastfeeding: Pregnancy Category C; use with caution. Excretion in breast milk unknown.
• Dosage: Head lice: 5% lotion applied to affected area, repeat after 7 days. Local anesthetic: As directed by healthcare provider. IV: varies depending on the medication.
• Monitoring Parameters: Monitor for skin irritation, allergic reactions, and signs of gasping syndrome in neonates. If used in injectable medications, monitor for signs of toxicity in patients with renal/hepatic impairment.

Popular Combinations

Not applicable for benzyl alcohol as a single agent.

Precautions

• General Precautions: Perform a skin test before applying to large areas to rule out allergy. Avoid contact with eyes and mucous membranes. Avoid using on broken or irritated skin.
• Specific Populations: Pregnant women (use with caution, weigh benefits against risks). Breastfeeding mothers (exercise caution, monitor infants for side effects). Children and elderly: adhere to age-specific guidelines.
• Lifestyle Considerations: No specific lifestyle considerations related to topical benzyl alcohol.

FAQs (Frequently Asked Questions)

Q1: What is the recommended dosage for Benzyl Alcohol for head lice?

A: Apply 5% benzyl alcohol lotion to dry hair and scalp, ensuring complete saturation. Leave on for 10 minutes, then rinse thoroughly with water. Repeat the treatment after 7 days.

Q2: Can Benzyl Alcohol be used in infants?

A: No, benzyl alcohol should not be used in infants younger than 6 months of age for head lice treatment, and intravenous formulations containing benzyl alcohol should not be used in neonates or preterm infants.

Q3: What are the common side effects of Benzyl Alcohol?

A: Common side effects include mild skin irritation, redness, itching, dryness, and temporary numbness at the application site.

Q4: Are there any serious side effects of Benzyl Alcohol?

A: Rare but serious side effects include allergic reactions (rash, hives, swelling, difficulty breathing) and, in neonates exposed to high doses of intravenous formulations, neurotoxicity, which can manifest as respiratory distress or neurological symptoms.

Q5: Can pregnant or breastfeeding women use Benzyl Alcohol?

A: Benzyl alcohol should be used with caution during pregnancy (Pregnancy Category C) and breastfeeding. Consult a healthcare provider to weigh the potential benefits against the potential risks. It’s unknown if benzyl alcohol is excreted in breast milk.

Q6: How does Benzyl Alcohol work to treat head lice?

A: Benzyl alcohol works by blocking the lice’s spiracles (breathing holes), leading to asphyxiation. It does not kill the eggs (nits), which is why a second treatment is necessary after 7 days to kill newly hatched lice.

Q7: What should I do if head lice persist after treatment with Benzyl Alcohol?

A: Consult a healthcare provider if head lice persist after a full course of treatment and retreatment with benzyl alcohol. They may recommend an alternative medication.

Q8: Can Benzyl Alcohol be used as a local anesthetic?

A: Yes, benzyl alcohol can be used as a topical local anesthetic to numb the skin and reduce pain. The dosage and application should be as directed by a healthcare provider.

Q9: What are the contraindications to using Benzyl Alcohol?

A: Benzyl alcohol is contraindicated in individuals with known hypersensitivity to it, in premature infants and neonates (for intravenous formulations), and in infants under 6 months of age (for head lice treatment).