Didanosine is converted intracellularly to its active form dideoxyadenosine triphosphate. This triphosphate halts the DNA synthesis of retrovirases, including HIV, through competitive inhibition of reverse transcriptase and incorporation into viral DNA.
Delavirdine acts by non-competitive inhibition of HIV-1 reverse transcriptase; it binds to the enzyme, disrupting the conformation of its catalytic site and impairing its RNA- and DNA-dependent polymerase activity. Resistance to delavirdine and emergence of cross-resistance to other non-nucleoside reverse transcriptase inhibitors has been seen.
Darunavir is a selective inhibitor of HIV-1 protease. It interferes with the formation of essential viral proteins making them incapable of infecting other cells. Viral resistance develops rapidly when HIV-protease inhibitors are given alone and therefore they are used with other antiretrovirals.
Cidofovir undergoes intracellular phosphorylation by cellular kinases to the antiviral metabolite, cidofovir diphosphate, which acts as a competitive inhibitor of viral DNA polymerase. It is active against a range of herpesviruses including CMV, and, since its activity is not reliant on viral enzymes, may retain activity against some aciclovir- and foscarnet-resistant viruses. Cross-resistance with ganciclovir is common.
Atazanavir is a selective, competitive, reversible inhibitor of HIV-1 protease. It interferes with the formation of essential viral proteins making them incapable of infecting other cells. Viral resistance develops rapidly when HIV-protease inhibitors are given alone and therefore they are used with other antiretrovirals.
Natamycin is a polyene antifungal active against Candida and Fusarium spp. In addition it is active against the protozoan Trichomonas vaginalis.
Miconazole is an imidazole antifungal with similar antimicrobial activity to that of ketoconazole. It also has some activity against Aspergillus spp., Cryptococcus neoformans, Pseudallescheria boydii, and some Gram-positive bacteria including staphylococci and streptococci.
Ketoconazole has a wide spectrum of antimicrobial activity including activity against Blastomyces dermatitidis, Candida spp., Coccidioides immitis, Epidermophyton floccosum, Histoplasma capsulatum, Malassezia spp., Microsporum canis, Paracoccidioides brasiliensis, Trichophyton mentagrophytes, and T. rubrum. Some strains of’Aspergillus spp., Cryptococcus neoformans, and Sporothrix schenckii are sensitive.
Itraconazole can be used to treat various superficial fungal infections, including dermatophytoses, pityriasis versicolor, and mucosal and cutaneous forms of candidosis.
Griseofulvin is a fungistatic antibiotic that inhibits fungal cell division by disruption of the mitotic spindle structure. It may also interfere with DNA production. It is active against the common dermatophytes, including some species of’ Epidermophyton, Microsporum, or Trichophyton.