Category: 10. Chemotherapeutic Agents

Viruses are obligate intracellular parasites; their replication depends primarily on synthetic processes of the host cell. Viral replication consists of several steps: (1) adsorption to and penetration into susceptible host cells; (2) uncoating of viral nucleic acid; (3) synthesis of early, regulatory proteins, eg, nucleic acid polymerases; (4) synthesis of RNA/ DNA; (5) synthesis of…

Itraconazole Itraconazole is available in an oral formulation and its absorption is increased by food and by low gastric pH. Undergoes extensive hepatic metabolism. Itraconazole is the azole of choice in the treatment of dermatophytoses and onychomycosis and is the only agent with significant activity against Aspergillus species. Fluconazole Fluconazole has good cerebrospinal fluid penetration.…

Clotrimazole and miconazole are available over-the-counter and are often used for vulvovaginal candidiasis. Oral clotrimazole troches are available for treatment of oral thrush and are a pleasant-tasting alternative to nystatin. In cream form, both agents are useful for dermatophytic infections, including tinea corporis, tinea pedis, and tinea cruris. Absorption is negligible, and adverse effects are…

Ketoconazole is less selective for fungal P450 than are the fluconazole and itraconazole (inhibit mammalian cytochrome P450 enzymes). Clinical use: it has limited use because of the drug interactions, endocrine side effects, and of its narrow therapeutic range. Oral formulation that is best absorbed at a low gastric pH. Ketoconazole is used in treatment of…

Flucytosine is related to fluorouracil (5-FU). Its spectrum of action is much narrower than that of amphotericin B. It is well absorbed orally. It is poorly protein-bound and penetrates well into all body fluid compartments including the CSF. It is eliminated by glomerular filtration. Toxicity is more likely to occur in AIDS patients and in…

Griseofulvin is a fungistatic and used is in the treatment of dermatophytosis. Absorption is improved when it is given with fatty foods. Griseofulvin is deposited in newly forming skin where it binds to keratin, protecting the skin from new infection. It must be administered for 2-6 weeks for skin and hair infections to allow the…

Nystatin has similar structure with amphotericin B and has the same pore-forming mechanism of action. It is too toxic for systemic use and is only used topically. It is not absorbed from skin, mucous membranes, or the gastrointestinal tract. Nystatin is active against most Candida species and is most commonly used for suppression of local…

Amphotericin B is poorly absorbed from the gastrointestinal tract. Oral amphotericin B is thus effective only on fungi within the lumen of the tract. The drug is widely distributed in tissues, but only 2-3% of the blood level is reached in CSF, thus occasionally necessitating intrathecal therapy for certain types of fungal meningitis. Mechanism of…

Fungal infections have increased in incidence and severity in recent years, due to increased in the use of broad-spectrum antimicrobials and the HIV epidemic. The antifungal drugs fall into two groups: antifungal antibiotics and synthetic antifungals.

Leprosy is caused by mycobacterium leprae. I t can be treated dapsone, rifampin, clofazimine, ethionamide, etc. Because of increasing reports of dapsone resistance, treatment of leprosy with combinations of the drugs is recommended. Dapsone Dapsone (diaminodiphenylsulfone) is the most widely used drugs in the treatment of leprosy and it inhibits folate synthesis. Resistance can emerge…