Topical Antiparasitic Agents
- Pregnancy Category B
- Organic compound, derived from flowers of Compositae
Formulations and Dosage
- 0.33 % lotion and shampoo
Head lice
- Apply to clean, dry hair for 10 min before washing (important that hair is dry or can become diluted)
Mechanism of Action
- Inhibits closure of voltage-gated Sodium channels inhibiting repolarization and paralyzing the mite, leading to its death
Indications
FDA
- Head lice
Side Effects
- Irritation
- Since derived from flowers of Compositae, can cross reacts in patients with ragweed allergy and formaldehyde
Other
- Combined with piperonyl butoxide (stabilize and increases duration)
- Pregnancy Category B
Formulations and Dosage
- Available as 5% cream (used for scabies) and 1% cream (used for pediculosis)
Scabies (Day 1 and Day 8)
- apply neck down (infants and young children, apply to scalp and face too); leave on overnight and wash off in AM
Head lice
- Shampoo hair first (no conditioner), towel dry then apply x10 min on days 1 and 8 then rinse out
Mechanism of Action
- Synthetic Pyrethrin: Inhibits closure of voltage-gated sodium channels inhibiting repolarization and paralyzing the mite, leading to its death
Indications
FDA
- scabies (age > 2 months)
Other
- Head lice and pubic lice (pediculosis capitis and pubis)
- Demodex folliculitis
Side Effects
- Local: irritation, xerosis, pruritis; mild and transient burning and stinging
- Not to be used in patients with Compositae allergy due to possibility of cross reaction; also with formaldehyde
Other
- Greater effectiveness against lice, scabies, and ticks compared to organic pyrethrin
- 1-2% systemic absorption with 5% cream
- the following are equivalent in terms of treatment of scabies: permethrin 5%, topical 1% ivermectin, oral ivermectin
- Resistance reported in scabies and lice with mutations in sodium channels
- Only 25% are lice free after treatment
- Pregnancy Category B
Formulations and Dosage
- 0.5% lotion
Head lice
- Apply to dry hair then rinse with shampoo after 8-12 hours (some studies show similar efficacy with 20-minute application); may re-treat in 1 week
Mechanism of Action
- Organophosphate cholinesterase inhibitor converted to malaoxon; irreversibly inhibits acetylcholinesterase leading to neuromuscular paralysis and death
Indications
FDA
- Head lice (pediculosis capitis)
Side Effects
- Flammable due to alcohol content, local irritation
- Toxic if ingested (organophosphate poisoning)
Other
- Best treatment for head lice
- Pregnancy Category C
Formulations and Dosage
- 0.5% lotion; 1% lotion
- Available in cream format
Scabies
- 1 application per week, repeat for 4 weeks
Head lice
- Applied to dry hair for 10 minutes then rinsed with water only (no shampoo or conditioner for 24 hours)
Mechanism of Action
- Binds GABA-gated chloride channels, leading to increased permeability and hyperpolarization with subsequent paralysis and death of the mite
Indications
FDA
- Pediculosis capitis (>6 months of age)
- Rosacea (1% cream applied once a day – presumed to be anti-inflammatory. The exact mechanism is unknown.)
Other
- Scabies (efficacy equivalent to topical permethrin)
Side Effects
- Skin irritation and localized burning
Other
- Can be used during lactation, but must avoid on nipple/areola area
- Pregnancy Category B
Formulations and Dosage
- 0.9% solution
Head lice
- Applied to dry hair then rinsed after 10 min; retreatment in 1 week
Mechanism of Action
- Excites motor neuron leading to muscle spasm, paralysis and death of the mite
Indications
FDA
- Pediculosis capitis (> 6 months of age)
Side Effects
- Skin irritation, erythema
Other
- Breastfeeding should be avoided for 8 hours after use
- Pregnancy Category C
Formulations and Dosage
- 1% shampoo or lotion
Mechanism of Action
- Organochloride (hydrocarbon) insecticide; inhibits nerve transmission of mite
Indications
- No longer used (previously used for scabies, lice)
Side Effects
- neurotoxicity, seizures
- heme: aplastic anemia, leukemia
Other
- Banned in most countries
- Pregnancy Category C
Formulations and Dosage
- 10% cream or lotion
Mechanism of Action
- Unknown, mainly anti-pruritic only and minimally effective for scabies
Indications
FDA
- Scabies
Side Effects
- * For further reading/information refer to a pharmacology source
Other
- Apply neck down for 2 consecutive days
- Pregnancy Category N/A
Formulations and Dosage
- 10-25% solution (compounded solution)
- Scabies: apply BID for 3 days; can be combined with oral ivermectin (single dose)
Mechanism of Action
- * For further reading/information refer to a pharmacology source
Indications
- Used in scabies
Side Effects
- Skin irritation
- Avoid EtOH for 48 hrs; causes disulfiram like reaction
Other
- Most common treatment for scabies in developing world due to cost-effectiveness
- Pregnancy Category N/A
Formulations and Dosage
- 5-10% (compounded in cream/ointment)
Mechanism of Action
- Antiseborrhiec, antiparasitic and keratolytic
Indications
- Used in scabies: applied for 24 hrs than washed off, repeat daily x 5 days total
Side Effects
- Odor and mild skin irritation
Other
- Mentioned to be treatment of choice for scabies in pregnancy however no studies available to support this
- Pregnancy Category N/A
Formulations and Dosage
- 5% oil
Mechanism of Action
- Melaleuca alternifolia oil leads to death of mites within 3 hours; also, anti-pruritic
Indications
- Used in scabies
Side Effects
- Allergic contact dermatitis, and can also act as a sensitizer
Other
- Can be an option for select patients
- Pregnancy Category C
Formulations and Dosage
- 10% lipophilic ointment (compounded)
- To be applied under occlusion 3-4 times/day for 5-10 days
Mechanism of Action
- Binds colchicine sensitive cells of tubulin in helminths leading to death of mite
Indications
- Cutaneous larva migrans
Side Effects
- Local irritation and skin ulceration
Other
- Good option in pregnancy and in young children or if oral ivermectin/albendazole is contraindicated