sm-8668 and Candidiasis

A series of 92 azole antifungals containing an amido alcohol unit was synthesized. The nature and substitution of the amide portion was systematically modified in search of improved antifungal activity, especially against filamentous fungi. The compounds were tested in vitro against a variety of clinically important pathogens and in vivo (po) in a murine candidosis model. Thiazole and thiophene carboxamides carrying both a substituted phenyl ring and a small alkyl group were best suited for activity against filamentous fungi. In a subset of these compounds, the amide portion was conformationally locked by means of a pyrimidone ring and it was proven that only an orthogonal orientation of the phenyl ring yields bioactive products. A tendency to display long plasma elimination half-lives was observed in both series. Two compounds, 74 and 107, representative of the open and cyclic amides, respectively, were chosen for further studies, based on their excellent activity in in vivo murine models of candidosis and aspergillosis. This work describes the SARs found within this series. The next paper displays the results obtained in a related series of compounds, the quinazolinones.

Topics: Animals; Antifungal Agents; Aspergillosis; Aspergillus fumigatus; Candidiasis; Colony Count, Microbial; Fungi; Male; Mice; Molecular Conformation; Pyrimidinones; Rats; Stereoisomerism; Structure-Activity Relationship; Thiazoles; Thiophenes; Triazoles

A series of azole antifungal agents featuring a quinazolinone nucleus have been subjected to studies of structure-activity relationships. In general, these compounds displayed higher in vitro activities against filamentous fungi and shorter half-lives than the structures described in our preceding paper. The most potent products in vitro carried a halogen (or an isostere) at the 7-position of the quinazolinone ring. Using a murine model of systemic candidosis, oral activity was found to be dependent on hydrophobicity, which, in turn, modulated the compound's half-life. The 7-Cl derivative, (1R,2R)-7-chloro-3-[2-(2, 4-difluorophenyl)-2-hydroxy-1-methyl-3-(1H-1,2, 4-triazol-1-yl)propyl]quinazolin-4(3H)-one (20, UR-9825), was selected for further testing due to its high in vitro activity, low toxicity, good pharmacokinetic profile, and ease of obtention. Compound 20 is the (1R,2R) isomer of four possible stereoisomers. The other three isomers were also prepared and tested. The enantiomer (1S,2S) and the (1R,2S) epimer were inactive, whereas the (1S,2R) epimer retained some activity. In vitro 20 was superior to fluconazole, itraconazole, SCH-42427, and TAK-187 and roughly similar to voriconazole and ER-30346. In vivo, 20 was only moderately active in a mouse model of systemic candidosis when administration was limited to the first day. This was attributed to its short half-life in that species (t1/2 = 1 h po). Protection levels comparable to or higher than those of fluconazole, however, were observed in systemic candidosis models in rat and rabbit, where the half-life of the compound was found to be 6 and 9 h, respectively. Finally, 20 showed excellent protection levels in an immunocompromised rat model of disseminated aspergillosis. The compound showed low toxicity signs when administered to rats at 250 mg/kg qd or at 100 mg/kg bid during 28 days.

Topics: Animals; Antifungal Agents; Aspergillosis; Aspergillus fumigatus; Candidiasis; Colony Count, Microbial; Fungi; Male; Mice; Molecular Conformation; Quinazolines; Rabbits; Rats; Rats, Sprague-Dawley; Stereoisomerism; Structure-Activity Relationship; Triazoles

Triazole analogues which contained alkylthio or alkylsulfonyl groups where synthesized as derivatives of antifungal SM-8668 and estimated for their in vitro and in vivo activity. Derivatives having pentylthio, heptylthio or nonylthio groups showed excellent efficacy against both candidiasis and aspergillosis. Introduction of a hydrophilic group at the end of their alkyl chain made their activity stronger. Especially, 5-hydroxypentylthio and 7-hydroxyheptylthio derivatives showed the strongest antifungal activity.

Topics: Alkylation; Animals; Antifungal Agents; Aspergillosis; Candidiasis; Disease Models, Animal; Magnetic Resonance Spectroscopy; Male; Mice; Structure-Activity Relationship; Sulfur; Triazoles

SCH 39304 was compared with fluconazole and ketoconazole in a systemic Candida albicans infection in mice (10(6) CFU per mouse). Results were based on survival rates and CFU in kidneys following once-daily oral treatment of 2, 5, or 10 days duration. In normal mice, SCH 39304 (dose to reduce kidney counts by 4 log units, 0.5 mg/kg of body weight) was 3 and 200 times more active than fluconazole and ketoconazole, respectively. In immunocompromised mice (gamma irradiation, 600 rads), SCH 39304 (dose to reduce kidney counts by 4 log units, 1.3 mg/kg) was 35 and greater than 100 times more active than fluconazole and ketoconazole, respectively. In normal mice, when the infecting inoculum varied from 10(5) to 10(7) CFU, only a fivefold increase in the dose to reduce kidney counts by 4 log units was observed with SCH 39304. Excellent protection was also seen when mice were treated with a single oral dose of SCH 39304 up to 24 h prior to infection with C. albicans. Studies in a systemic C. albicans infection model indicated that SCH 39304 is equally efficacious following either oral or intravenous administration. In a systemic Aspergillus flavus infection, mice treated with SCH 39304 (5 mg/kg) survived twice as long (16 days) as those treated with fluconazole (50 mg/kg) or controls did.

Topics: Administration, Oral; Animals; Antifungal Agents; Aspergillosis; Candidiasis; Drug Evaluation, Preclinical; Fluconazole; Injections, Intravenous; Ketoconazole; Kidney; Male; Mice; Triazoles

SCH 39304, a new triazole antifungal agent, is a 50:50 racemic mixture of two enantiomers, SCH 42427 and SCH 42426. The activities of these three compounds were compared in a series of in vitro and in vivo experiments. SCH 42427 was twofold more active in vitro against a variety of yeasts and dermatophytes than SCH 39304, while SCH 42426 was inactive (MICs greater than 64 micrograms/ml). In a systemic Candida albicans infection in mice, SCH 42427 administered orally (p.o.) (50% protective dose [PD50], 0.17 mg/kg of body weight; 50% effective dose, [ED50], 0.47 mg/kg) had greater efficacy than SCH 39304 (PD50, 0.21 mg/kg; ED50, 0.62 mg/kg) and SCH 42426 (greater than 100 mg/kg for PD50 and ED50). In a pulmonary Aspergillus flavus infection in mice, SCH 42427 p.o. (PD50, 13 mg/kg) was also more effective than SCH 39304 (18 mg/kg) and SCH 42426 (greater than 250 mg/kg). In a C. albicans vaginal infection in hamsters, SCH 42427 p.o. (ED50, 3.5 mg/kg) was more active than SCH 39304 (8.5 mg/kg) and SCH 42426 (320 mg/kg). Following topical administration, against a Trichophyton mentagrophytes infection in guinea pigs, SCH 42427 was about 2-fold more active than SCH 39304 and about 100-fold more active than SCH 42426. These and other results indicated that SCH 42427 is the active enantiomer, responsible for all the antifungal activity observed with SCH 39304.

Topics: Animals; Antifungal Agents; Aspergillosis; Aspergillus flavus; Candidiasis; Candidiasis, Vulvovaginal; Cricetinae; Dermatomycoses; Female; Fungi; Guinea Pigs; Male; Mesocricetus; Mice; Microbial Sensitivity Tests; Rats; Rats, Inbred Strains; Stereoisomerism; Triazoles; Trichophyton

Mice infected intravenously with Candida albicans were treated with SCH 39304, a new triazole antifungal compound, amphotericin B, or both. Two dose levels of each drug were evaluated in an attempt to identify potential helpful or harmful effects on survival and kidney colony counts. Contrary to theoretical predictions, combination therapy was not antagonistic and some additive or synergistic effects were observed. The results obtained in this study suggest that antagonism between polyene and azole antifungal drugs is not inevitable and that additive or synergistic effects may be possible.

Topics: Amphotericin B; Animals; Antifungal Agents; Candidiasis; Drug Interactions; Drug Synergism; Drug Therapy, Combination; Female; Kidney; Mice; Mice, Inbred ICR; Triazoles

To investigate the potential use of SCH-39304 for the prevention and treatment of disseminated candidiasis in granulocytopenic patients, we studied its in vivo antifungal activity as preventive, early, and late treatments in three models (acute, subacute, and chronic) of disseminated candidiasis in persistently granulocytopenic rabbits. SCH-39304 was an effective as amphotericin B alone and fluconazole alone for the prevention of disseminated candidiasis. SCH-39304 alone and fluconazole alone were as effective as amphotericin B plus flucytosine for early treatment of subacute disseminated candidiasis. When treatment was delayed for 5 days to establish chronic disseminated candidiasis, SCH-39304 was less effective than amphotericin B plus flucytosine. In comparison with different treatment regimens, SCH-39304 was more effective in early and preventive treatment. Thus, SCH-39304 was comparable to treatment control regimens in prevention and early treatment of subacute disseminated candidiasis. SCH-39304 also was most effective in granulocytopenic rabbits with disseminated candidiasis when used for prevention or early treatment.

Topics: Agranulocytosis; Amphotericin B; Animals; Anti-Bacterial Agents; Antifungal Agents; Candida albicans; Candidiasis; Disease Models, Animal; Female; Fluconazole; Immunosuppression Therapy; Rabbits; Triazoles

We studied the pharmacokinetics and in vivo antifungal action of SCH39304, a new antifungal azole compound, in rabbits. It crossed the blood-cerebrospinal fluid barrier in the presence or absence of meningeal inflammation, reaching approximately 60% of the simultaneous concentrations in serum. In the treatment of experimental cryptococcal meningitis, SCH39304 was as effective as fluconazole in reducing yeast counts in the subarachnoid space. SCH39304 and fluconazole both were highly effective against candida endophthalmitis, sterilizing the vitreous humor and the choroid and retina. SCH39304 suppressed candida endocarditis and reduced yeast counts in the kidney at all doses tested. SCH39304 was effective in the treatment of experimental cryptococcal meningitis and disseminated candidiasis. Further investigations in humans are warranted.

Topics: Animals; Antifungal Agents; Candida albicans; Candidiasis; Cryptococcosis; Cryptococcus neoformans; Fluconazole; Meningitis; Microbial Sensitivity Tests; Rabbits; Triazoles