Antifungal p.5

Allylamine Antifungal Agent

• Terbinafine is the prototype drug for the allylamine antifungal class.
• Terbinafine is highly effective against dermatophytes, but less effective against Candida species.
• Other agents in this class include naftifine.

Mechanism of Action

• Terbinafine inhibits squalene epoxidase, which is an enzyme crucial for ergosterol synthesis in fungal cells.
• Ergosterol is a vital component of the fungal cell membrane.
• By inhibiting ergosterol synthesis, terbinafine disrupts the fungal cell membrane, leading to fungal cell death.

Indications and Therapeutic Uses

• Oral terbinafine is used to treat systemic fungal infections such as tinea and onychomycosis.
• Topical terbinafine is used to treat superficial fungal infections such as tinea corporis, tinea cruris, and tinea pedis.

Side Effects & Adverse Reactions

• Gastrointestinal upset, such as diarrhea, dyspepsia, and abdominal pain.
• Skin reactions can occur.
• Taste disturbances can occur.
• Hepatotoxicity is a serious adverse effect, with reported cases of liver transplantation and fatality.

Precautions & Contraindications

• Terbinafine is contraindicated for clients with preexisting hepatic disease.

Drug Interactions

• Terbinafine's effectiveness may be reduced when taken orally with rifampin.
• Terbinafine plasma levels can increase when taken with cimetidine or inhibitors of CYP2C9 and CYP3A4, such as fluconazole, ketoconazole, and amiodarone.
• Terbinafine can potentially increase the effects of caffeine or drugs metabolized by CYP2D6, such as tricyclic antidepressants, SSRIs, and beta-blockers.

Dosing, Administration, & Client Teaching

• Dosing for terbinafine varies depending on the condition, its severity, and the client's response.
• Terbinafine oral tablets are available in 250 mg strengths.
• Consult drug dosing guidelines for individualized dosing.

Allylamine Antifungal Agents

• Terbinafine (Lamisil) is the prototype drug in this allylamine antifungal class
• The primary function of terbinafine is to inhibit the synthesis of ergosterol, a key component of fungal cell membranes
• The drug works by inhibiting squalene epoxidase, an enzyme involved in ergosterol synthesis
• Other drugs in this class include naftifine

Indications and Uses

• Systemic fungal infections such as tinea and onychomycosis (oral use)
• Superficial fungal infections such as tinea infections of the body, groin, and feet (topical use)

Side Effects and Adverse Reactions

• Gastrointestinal upset: Diarrhea, dyspepsia, and abdominal pain
• Skin reactions
• Taste disturbances
• Hepatotoxicity: Liver transplantation and fatality have been reported

Precautions and Contraindications

• Contraindicated for clients with pre-existing hepatic disease

Drug Interactions

• Rifampin antagonizes terbinafine when taken orally
• Cimetidine, CYP2C9 and CYP3A4 inhibitors such as fluconazole, ketoconazole, and amiodarone may increase terbinafine plasma levels
• Terbinafine may potentiate the effects of caffeine or drugs metabolized by CYP2D6, such as tricyclic antidepressants, SSRIs, and beta-blockers

Dosing, Administration, & Client Teaching

• Dosing varies based on the condition, severity, and client response
• Consult drug dosing guidelines for individualized dosing
• Oral terbinafine is available in 250 mg tablets

Allylamine Antifungal Agent

• The prototype drug for this class is terbinafine (Lamisil).
• Terbinafine is highly active against dermatophytes, but has less activity against Candida species.
• Other members of this class include naftifine.

Mechanism of Action

• Terbinafine inhibits squalene epoxidase, which is a key enzyme involved in ergosterol synthesis.
• Ergosterol is a crucial component of the fungal cell membrane.
• By interfering with ergosterol synthesis, terbinafine disrupts the fungal cell membrane, leading to cell death.

Indications and Therapeutic Uses

• Systemic Fungal Infections: Oral terbinafine is used to treat systemic fungal infections, including tinea infections (like ringworm) and onychomycosis (fungal nail infections).
• Superficial Fungal Infections: Topical terbinafine is used to treat superficial fungal infections, including tinea corporis (body ringworm), tinea cruris (jock itch), and tinea pedis (athlete's foot).

Adverse Reactions and Side Effects

• Common Side Effects: Gastrointestinal upset (e.g., diarrhea, dyspepsia, abdominal pain), skin reactions (e.g., rash), and alterations in taste.
• Serious Adverse Effect: Hepatotoxicity (liver damage), which can be severe and may even lead to liver transplantation or death.

Precautions and Contraindications

• Contraindication: Terbinafine is contraindicated in individuals with pre-existing hepatic disease.

Drug Interactions

• Antagonism: Rifampin antagonizes oral terbinafine.
• Increased Plasma Levels: Terbinafine plasma levels can be increased by inhibitors of CYP2C9 and CYP3A4, such as cimetidine, fluconazole, ketoconazole, and amiodarone.
• Potentiation: Terbinafine may potentiate the effects of caffeine and drugs metabolized by CYP2D6, such as tricyclic antidepressants, SSRIs, and beta-blockers.

Dosing and Administration

• Dosing varies depending on the specific condition, severity of infection, and patient response.
• Consult drug dosing guidelines for individualized dosing recommendations.
• Oral terbinafine is available in 250 mg tablets.

Allylamine Antifungal Agent

• Terbinafine is a highly active antifungal agent against dermatophytes, but has less activity against Candida species.
• Naftifine is another example of an allylamine antifungal agent.

Mechanism of Action

• Terbinafine inhibits squalene epoxidase, which results in the inhibition of ergosterol synthesis.
• Ergosterol synthesis is essential for the fungal cell membrane.

Indications

• Oral terbinafine is used to treat systemic fungal infections, such as tinea and onychomycosis.
• Topical terbinafine is used to treat superficial fungal infections, including tinea corporis, cruris, and pedis.

Side Effects and Adverse Reactions

• Common side effects include gastrointestinal upset, skin reactions, and taste disturbances.
• Hepatotoxicity, including liver transplantation and fatality, has been reported.

Precautions and Contraindications

• Terbinafine is contraindicated for clients with preexisting hepatic disease.

Drug Interactions

• Terbinafine is antagonized by rifampin when taken orally.
• Terbinafine plasma levels may be increased by cimetidine or CYP2C9 and CYP3A4 inhibitors, such as fluconazole, ketoconazole, and amiodarone.
• Terbinafine may potentiate the effects of caffeine or drugs metabolized by CYP2D6, such as tricyclic antidepressants, SSRIs, and beta-blockers.

Dosing

• Dosing varies based on the condition, severity, and client response.
• Oral terbinafine is available in 250 mg tablets.

Allylamine Antifungal Agent

• Terbinafine is a highly effective antifungal agent targeting dermatophytes
• It shows less effectiveness against Candida species
• Naftifine is another representative of this class

Mechanism of Action

• Terbinafine inhibits squalene epoxidase
• This inhibits ergosterol synthesis
• Ergosterol is a key component of the fungal cell membrane

Indications and Therapeutic Uses

• Oral terbinafine is used for systemic fungal infections like tinea and onychomycosis
• Topical terbinafine is indicated for superficial fungal infections, including tinea corporis, cruris, and pedis

Side Effects and Adverse Reactions

• Common gastrointestinal side effects include diarrhea, dyspepsia, and abdominal pain
• Skin reactions are a possibility
• Taste alterations are possible
• Hepatotoxicity can occur, with reports of liver transplantation and fatality

Precautions and Contraindications

• Terbinafine is contraindicated for individuals with preexisting liver disease

Drug Interactions

• Terbinafine's effectiveness is reduced when taken orally with rifampin
• Cimetidine and CYP2C9 and CYP3A4 inhibitors (such as fluconazole, ketoconazole, and amiodarone) can increase terbinafine plasma levels
• Terbinafine can enhance the effects of caffeine or drugs metabolized by CYP2D6, including tricyclic antidepressants, SSRIs, and beta-blockers

Dosing and Administration

• Dosing varies based on the specific condition, severity, and client response
• Refer to drug dosing guidelines for individualized dosing
• Oral terbinafine is available in 250 mg tablets

Terbinafine

• Terbinafine is an allylamine antifungal agent primarily targeting dermatophytes.
• It is effective against fungal infections like tinea and onychomycosis, including tinea corporis, cruris, and pedis.
• Terbinafine inhibits squalene epoxidase, disrupting ergosterol synthesis, a vital component of the fungal cell membrane.

Indications & Uses

• Terbinafine is available in oral and topical formulations.
• Oral terbinafine is indicated for systemic fungal infections.
• Topical terbinafine is used for superficial fungal infections.

Side Effects & Adverse Reactions

• Common side effects include gastrointestinal upset (diarrhea, dyspepsia, abdominal pain), skin reactions, and taste disturbances.
• A serious adverse effect is hepatotoxicity, which can lead to liver transplantation and death.

Precautions & Contraindications

• Terbinafine is contraindicated in individuals with preexisting hepatic disease.

Drug Interactions

• Terbinafine is antagonized by rifampin.
• Terbinafine plasma levels may increase with cimetidine or inhibitors of CYP2C9 and CYP3A4, including fluconazole, ketoconazole, and amiodarone.
• Terbinafine can potentiate the effects of caffeine and drugs metabolized by CYP2D6, such as tricyclic antidepressants, SSRIs, and beta-blockers.

Dosing & Administration

• Dosing varies based on the condition, severity, and individual client response.
• Always refer to drug dosing guidelines for individualized dosing.
• Oral terbinafine is available in 250 mg tablets.

Allylamine Antifungal Agent

• Terbinafine (Lamisil) is a highly active antifungal agent, primarily targeting dermatophytes with a lesser effect on Candida species.
• Naftifine is another representative agent in this class.

Mechanism of Action

• Terbinafine inhibits squalene epoxidase, which disrupts ergosterol synthesis.
• Ergosterol is crucial for the fungal cell membrane's integrity.

Indications

• Systemic Fungal Infections: Oral terbinafine is indicated for systemic fungal infections, such as tinea and onychomycosis.
• Superficial Fungal Infections: Topical terbinafine is indicated for superficial fungal infections, including tinea corporis, cruris, and pedis.

Side Effects and Adverse Reactions

• Gastrointestinal Upset: Common side effects include diarrhea, dyspepsia, and abdominal pain.
• Skin Reactions: Dermatologic side effects can occur.
• Taste Disturbance: Alterations in taste perception are possible.
• Hepatotoxicity: A severe adverse effect, terbinafine has been associated with liver transplantation and fatality.

Precautions and Contraindications

• Contraindications: Terbinafine is contraindicated for individuals with pre-existing hepatic disease.

Drug Interactions

• Rifampin: Antagonizes terbinafine's effects when taken orally.
• Cimetidine, CYP2C9, and CYP3A4 inhibitors (fluconazole, ketoconazole, amiodarone): Increase terbinafine plasma levels.
• Caffeine and drugs metabolized by CYP2D6 (tricyclic antidepressants, SSRIs, beta-blockers): Terbinafine may potentiate their effects.

Dosing

• Dosing is individualized, considering factors like the condition, severity, and patient response.
• Oral terbinafine is available in 250 mg tablets.