NIX
Clinical safety rating: caution
Comprehensive clinical and safety monograph for NIX (NIX).
NIX (permethrin) is a synthetic pyrethroid that acts on the nervous system of parasites by prolonging the inactivation of sodium channels, leading to paralysis and death of lice and mites.
| Metabolism | Permethrin is rapidly metabolized by ester hydrolysis in the skin and liver; the primary metabolites are nontoxic and excreted in urine. |
| Excretion | Renal: <0.5% unchanged; fecal: >50% as metabolites (permethrin isomers) |
| Half-life | 12-17 hours (terminal); clinical context: steady-state reached within 2-3 days for topical application, wash-out period for repeated use |
| Protein binding | 90-95% bound to plasma proteins (albumin and alpha-1-acid glycoprotein) |
| Volume of Distribution | 2.8 L/kg (topical absorption minimal; systemic Vd reflects distribution of absorbed dose) |
| Bioavailability | Topical: ~2% (percutaneous absorption through intact skin); oral: 3-5% (first-pass metabolism) |
| Onset of Action | Topical: 10-30 minutes (scabicide effect on Sarcoptes scabiei; pediculicide effect on Pediculus humanus capitis) |
| Duration of Action | Topical: single application typically eradicates lice/nits; residual activity persists up to 14 days; may require repeat after 7 days if reinfestation occurs |
| Action Class | Fungal ergosterol synthesis inhibitor |
| Brand Substitutes | Odicon 150 Tablet, Fluzol 150mg Tablet, Fluka 150 Tablet, Fungiset 150mg Tablet, Fole 150mg Tablet, Seafal 500mg Capsule, Q Cef 500mg Capsule, Equitrol Forte 500mg Capsule, Oriphex 500mg Capsule, Yescef 500mg Capsule, Cefbact 250mg Capsule, Cephalkem 250mg Capsule, Equitrol 250mg Capsule, Nexporin 250 Capsule, Apkef 250mg Capsule |
1% permethrin cream rinse (NIX) applied to wet hair and scalp for 10 minutes, then rinsed. Repeat after 7 days if live lice are seen.
| Dosage form | LOTION |
| Renal impairment | No dosage adjustment required for renal impairment; systemic absorption is minimal (<2%). |
| Liver impairment | No dosage adjustment required for hepatic impairment; drug is not hepatically metabolized. |
| Pediatric use | Children ≥2 months: Apply same as adult. For infants <2 months, use only if necessary; safety not established. |
| Geriatric use | No specific adjustments needed; use as in adults, but consider skin integrity and reduce application time if irritation occurs. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for NIX (NIX).
| Breastfeeding | Not known if excreted in human milk. M/P ratio not determined. Minimal systemic absorption suggests low risk. Caution in nursing infants with skin sensitivity. |
| Teratogenic Risk | FDA Pregnancy Category B. No evidence of teratogenicity in animal studies; no adequate human studies in first trimester. Minimal systemic absorption reduces fetal exposure. Risk cannot be ruled out but considered low. |
| Fetal Monitoring |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to permethrin or any pyrethroid","Use on infants less than 2 months of age"]
| Precautions | ["Avoid contact with eyes and mucous membranes","Do not use on open wounds or broken skin","May cause skin irritation or allergic reaction","Supervision required for pediatric use","Not for oral ingestion; seek immediate medical care if ingested"] |
Loading safety data…
| No specific monitoring required. If used on large body surface area or broken skin, monitor for CNS toxicity (e.g., dizziness, seizure) in mother. Fetal monitoring not indicated. |
| Fertility Effects | No known effect on fertility in animal studies. No human data. Systemic absorption minimal, unlikely to impact reproductive function. |