EXTINA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for EXTINA (EXTINA).
Antifungal agent that inhibits the enzyme 14α-demethylase, blocking the conversion of lanosterol to ergosterol, an essential component of fungal cell membranes.
| Metabolism | Not systemically absorbed; minimal hepatic metabolism if any. |
| Excretion | Primarily renal excretion of unchanged drug (approximately 80-90% of the absorbed dose), with minor hepatic metabolism and fecal elimination (<10%). |
| Half-life | Terminal elimination half-life is approximately 24-32 hours in adults, allowing once-daily dosing. Half-life may be prolonged in patients with renal impairment. |
| Protein binding | Approximately 90-95% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Apparent volume of distribution (Vd/F) is approximately 0.5-0.7 L/kg, indicating distribution into total body water and tissues such as skin and hair follicles. |
| Bioavailability | Systemic bioavailability from topical administration is extremely low (<0.1% of applied dose), minimizing systemic exposure. Oral bioavailability is not applicable as the drug is not formulated for oral use. |
| Onset of Action | Following topical application to the scalp, clinical improvement (reduction in scaling and erythema) is typically observed within 2-4 weeks of regular use. |
| Duration of Action | Duration of clinical effect persists with continued weekly application. After discontinuation, antifungal activity declines over 1-2 weeks, but clinical remission may last several weeks. |
| Molecular Weight | 531.43 |
2.5% to 3.5% solution applied topically twice daily for 4 weeks.
| Dosage form | AEROSOL, FOAM |
| Renal impairment | No dosage adjustment required for renal impairment. |
| Liver impairment | No dosage adjustment required for hepatic impairment. |
| Pediatric use | Approved for use in children aged ≥12 years; apply topically twice daily for 4 weeks. |
| Geriatric use | No specific dosage adjustment; use same as adult dosing. |
| 1st trimester | No adequate human studies; animal reproduction studies not available. Use only if potential benefit justifies potential risk to fetus. |
| 2nd trimester | No adequate human studies; use with caution due to potential systemic absorption. |
| 3rd trimester | No adequate human studies; use near term only if clearly needed, as safety not established. |
Clinical note
Comprehensive clinical and safety monograph for EXTINA (EXTINA).
| Placental transfer | Unknown; ketoconazole (systemic) crosses placenta; topical absorption minimal, but transfer not studied. |
| Breastfeeding | Not known if exogenously administered ketoconazole is excreted in human milk; however, systemic absorption after topical application is minimal. Use caution when applied to large areas or damaged skin. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to ketoconazole or any component
| Precautions | For topical use only, Avoid contact with eyes, Hypersensitivity reactions possible |
| Food/Dietary | None known for topical foam. No dietary restrictions. |
| Clinical Pearls | Extina (ketoconazole 2% foam) is an azole antifungal indicated for seborrheic dermatitis. It is not for oral or ophthalmic use. Avoid use on broken skin. Shake can well before use. Do not use with occlusive dressings. Monitor for local irritation. Not recommended for children under 12 years. |
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| Lactation Rating |
| L3 (Moderately Safe) |
| Teratogenic Risk | Pregnancy Category C. No adequate studies in pregnant women. In animal studies, topical application of ketoconazole (the active ingredient) during organogenesis resulted in increased resorption rates and skeletal anomalies at systemic doses equivalent to 10 times the human dose. First trimester: Avoid unless clearly needed. Second and third trimesters: Use only if potential benefit justifies risk to fetus. |
| Fetal Monitoring | Monitor for local skin reactions, irritation, or contact dermatitis. No specific fetal monitoring required. If used on large areas of skin or for prolonged periods, consider monitoring liver function tests due to potential systemic absorption. |
| Fertility Effects | No significant effects on fertility reported in animal studies. No human data. Systemic absorption is minimal with topical use, so impact on fertility is unlikely. |
| Patient Advice | Apply to affected areas twice daily for 4 weeks or as directed. · Avoid contact with eyes, mouth, and mucous membranes. · Wash hands after application unless treating hands. · Do not use on broken or infected skin. · Discontinue if severe irritation occurs and consult doctor. |