The quinolones inhibit DNA synthesis through a specific action on DNA gyrase.

Methenamine is metabolized to formaldehyde and ammonia and is used in urinary tract infections.

ISONIAZID inhibits synthesis of mycolic acids.

There are fast and slow acetylators of ISONIAZID.

ISONIAZID is associated with hepatotoxicity and peripheral neuropathy.

ISONIAZID is the drug of choice for chemoprophylaxis in recent converters.

RIFAMPIN inhibits RNA synthesis by formation of a stable complex with the DNA-dependent RNA polymerase.

RIFAMPIN is metabolized in the liver and is a potent inducer of the P-450 enzymes. It can cause hepatitis and may color secretions red-orange.

PYRAZINAMIDE is only effective against M tuberculosis. It increases levels of serum uric acid.

DAPSONE is the mainstay in the treatment of leprosy.

The azoles are broad-spectrum fungistatic agents that inhibit the synthesis of ergosterol by inhibiting the 14-α-demethylase enzyme.

The polyene antifungals, AMPHOTERICIN B and nystatin, work by binding to ergosterol, the principal fungal membrane sterol.

AMPHOTERICIN B is most commonly used to treat serious disseminated yeast and fungal infections, particularly in immunocompromised patients.

Nystatin is too toxic for systemic use. Its use is limited to topical treatment for Candida albicans.

The most serious and most common toxicity of AMPHOTERICIN B is nephrotoxicity.

AMPHOTERICIN B is not absorbed from the gastrointestinal (GI) tract, so it must be given intravenously or topically.

Terbinafine is administered orally for treatment of superficial fungal infections.

Terbinafine prevents ergosterol synthesis by inhibiting squalene epoxidase.

Terbinafine and tolnafatate inhibit squalene epoxidase, resulting in the accumulation of squalene inside the fungal cells. Terbinafine is effective against the skin and nail fungi.

AMANTADINE is used for the prevention and treatment of influenza type A infections.