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. |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for EXTINA (EXTINA).
| Breastfeeding | Systemic absorption after topical application is negligible (<0.1% of dose). No data on ketoconazole in human milk; however, due to low systemic exposure, risk to nursing infant is likely minimal. Use with caution. M/P ratio: Not available. |
| 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. |
■ FDA Black Box Warning
None
| Serious Effects |
["Known hypersensitivity to ketoconazole or any component of the formulation"]
| Precautions | ["For topical use only","Avoid contact with eyes","Hypersensitivity reactions possible"] |
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| 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. |