188: Antifungals Flashcards
(114 cards)
What is the mechanism of action of allylamines in antifungal therapy?
Allylamines suppress ergosterol synthesis by inhibiting the action of the squalene epoxidase enzyme, leading to a deficiency of ergosterol which results in a fungistatic effect. Additionally, the buildup of squalene contributes to its fungicidal activity.
What are the clinical indications for naftifine?
Naftifine is indicated for the treatment of interdigital tinea pedis, tinea cruris, tinea corporis, tinea versicolor, and Candida infections.
What are the common side effects associated with terbinafine?
Common side effects of terbinafine include dryness, pruritus, local irritation, and erythema for topical applications. For oral administration, unique side effects may include altered taste, which can last up to 6 weeks, and hepatotoxicity leading to organ failure.
How does the pharmacokinetics of terbinafine differ from that of naftifine?
Terbinafine has a long half-life of 17 hours and is rapidly distributed to hair follicles, nails, and skin, with minimal plasma concentrations. In contrast, naftifine’s systemic absorption is low (3%-6%) and therapeutic drug levels can persist in the stratum corneum for up to 5 days after a single application.
What formulations are available for terbinafine and how is it administered?
Terbinafine is available in cream, powder, solution, spray, and gel (1%). For oral administration, it is typically given as a single daily application for 2 to 4 weeks, with formulations including 250-mg tablets and oral granules.
What is the mechanism of action of terbinafine?
Terbinafine suppresses the squalene epoxidase enzyme, blocking the formation of ergosterol. This leads to a deficiency of ergosterol (fungistatic effect) and a buildup of squalene (fungicidal activity), making it effective against dermatophytes.
How does terbinafine’s efficacy compare to griseofulvin for tinea capitis?
Terbinafine is less effective than griseofulvin in eradicating ectothrix tinea capitis.
How long do therapeutic drug levels of naftifine persist in the stratum corneum after a single application?
Therapeutic drug levels of naftifine persist in the stratum corneum for up to 5 days following a single application.
What is the recommended dosage and duration of terbinafine for tinea pedis?
For tinea pedis, terbinafine is prescribed at 250 mg once daily for 2 to 4 weeks.
What is the recommended dosage and duration of naftifine for tinea pedis?
For tinea pedis, naftifine 1% gel or cream is applied once daily for 2 to 4 weeks.
What is the recommended dosage and duration of terbinafine for tinea cruris?
For tinea cruris, terbinafine is prescribed at 250 mg once daily for 2 to 4 weeks.
What is the recommended dosage and duration of naftifine for tinea cruris?
For tinea cruris, naftifine 1% gel or cream is applied once daily for 2 to 4 weeks.
How does terbinafine’s pharmacokinetics contribute to its efficacy?
Terbinafine’s lipophilic properties allow it to rapidly distribute and accumulate in hair follicles, nails, and skin, with minimal plasma concentrations, contributing to its efficacy.
What is the mechanism of action of Butenafine in antifungal treatment?
Butenafine inhibits the synthesis of ergosterol, enhancing membrane permeability and leakage of important cellular components, resulting in mycotic cell death.
What are the clinical uses of Butenafine?
Butenafine is used for the treatment of dermatophyte infections, with efficacy superior to that of allylamines. It can also be used in cases of pityriasis versicolor (PV) and candidiasis.
What are the common side effects associated with Butenafine?
Common side effects of Butenafine include itching, burning, erythema, and contact dermatitis.
What is the role of azoles in antifungal therapy?
Azoles inhibit the lanosterol demethylase enzyme (14α-demethylase), blocking the conversion of lanosterol into ergosterol, which is essential for fungal cell membrane integrity.
How do the concentrations of azoles affect their antifungal activity?
Azoles exhibit fungistatic activity at normal concentrations and fungicidal activity at high concentrations.
What are the clinical implications of using antifungals in patients with advanced renal or liver diseases?
In patients with advanced renal or liver diseases, the use of antifungals may require careful monitoring due to the potential for increased toxicity and adverse effects.
How does Butenafine’s efficacy compare to allylamines for dermatophyte infections?
Butenafine inhibits ergosterol synthesis, enhancing membrane permeability and causing mycotic cell death. It has superior efficacy compared to allylamines for dermatophyte infections.
What is the recommended dosage and duration of Butenafine for tinea pedis?
For tinea pedis, butenafine 1% cream is applied once daily for 2 to 4 weeks.
What is the mechanism of action of Clotrimazole?
Clotrimazole disrupts mycotic phospholipids, leading to leakage of intracellular iron, degradation of nucleic acids, and suppression of cell respiration.
What are the common formulations of Ketoconazole?
Ketoconazole is available in 5% shampoo, 2% cream, and 200-mg tablets.
What is the clinical significance of Miconazole’s absorption characteristics?
Miconazole efficiently penetrates the stratum corneum with less than 1% absorbed into systemic circulation, making it effective for localized infections like tinea cruris, corporis, and pedis.