[1st clinical experience with a new oral antimycotic in systemic mycoses]

[Manfred Plempel--his life and work]

The biography of Dr. Manfred Plempel (1930-1994), Chief Mycologist of the Bayer AG, who developed the first antifungal azole, clotrimazole, for clinical applicability is presented.

Clotrimazole, an imidazole antimycotic, is a potent inhibitor of angiogenesis

Clotrimazole, an imidazole antimycotic, interferes with the rise in cytosolic Ca2+ and inhibits cell proliferation in a reversible manner. Here we describe the effect of clotrimazole on vascular endothelial cells (ECs). Clotrimazole inhibited the proliferation of ECs stimulated with typical angiogenic growth factors; vascular endothelial growth factor and basic fibroblast growth factor (bFGF). This inhibitory effect of clotrimazole was dose-dependent and the maximal inhibition was observed at a concentration of 10 mM. We did not observe any increase in 51Cr release from ECs during treatment with 10 microM clotrimazole. Moreover, clotrimazole inhibited the basal and bFGF-stimulated migration of ECs. As clotrimazole inhibited two principle components of angiogenesis; the proliferation and migration of ECs, we examined whether clotrimazole inhibited angiogenesis. Tube formation by ECs in type 1 collagen gel was investigated, and clotrimazole was found to be significantly inhibitory. The inhibitory effect of clotrimazole on angiogenesis was further confirmed in an in vivo angiogenesis model of murine Matrigel plug assay. These results demonstrate that clotrimazole is a potent inhibitor of angiogenesis.

Experimental in vitro and in vivo comparison of modern antimycotics

Studies were carried out with the current leading antimycotic agents, using identical test methods, to compare their activity in vitro and in animal in vivo experiments. In the broth dilution test, the minimum inhibitory concentrations against approximately 50 strains of the most important species of yeasts, dermatophytes and moulds were determined using different culture media. Efficacy against yeasts was examined in experimentally-induced candidosis in mice treated orally, and against dermatophytes in experimentally-induced trichophytia in guinea pigs receiving topical treatment. The results showed that the imidazole derivatives studied can be regarded as true broad-spectrum antimycotics, and clotrimazole, in particular, had a well-balanced overall effect. The significance of the experimental data with respect to therapeutic efficacy in man in various indications is discussed.

Basic experiments with clotrimazole administered orally

A series of experiments was carried out with the antimycotic agent clotrimazole to establish MICs against a number of different yeasts and to estimate its blood levels following oral administration. Marked differences were noted between the MIC against A and B serotypes of Candida albicans in its yeast-like cell form, that against Type B being nearly 10-times higher than against Type A. Against the mycelial form, however, the MIC was much lower and there was little difference between the levels for the two serotypes. Clotrimazole administered in oral tablet form appeared to be poorly absorbed, little being transferred to the blood. Urinary levels were low and large amounts of the drug were detected in the faeces. Serum levels were below MIC levels in all cases examined. Blood levels 3-times as great as those after the same dosage in tablet form were produced when clotrimazole was given in oil solution and even with 250 mg, effective blood levels were achieved and maintained.

Surgical treatment of Candida endocarditis

Case reports from a group of 15 patients with Candida endocarditis seen and treated at the Los Angeles-University of Southern California Medical Center between 1960 and 1974, together with a survey of other reported cases, serve to re-emphasize the importance of early diagnosis of this disease and lead to certain conclusions regarding its treatment. With medical or surgical treatment alone, the mortality for Candida endocarditis is 82 per cent. With surgery and medical treatment combined, the mortality is 20 percent. It is important to institute medical treatment as soon as diagnosis of Candida endocarditis is made and surgery must be performed as soon as possible, preferably within 24 to 48 hours or, at most, a few days after the patient has left the hospital. Close observation of the patient after discharge is important.

Clotrimazole (Bay b 5097): in vitro and clinical pharmacological studies

Clotrimazole (Bay b 5097) is a new synthetic antifungal drug with in vitro activity against Candida spp., Torulopsis glabrata, and Saccharomyces spp. Pharmacological studies in man after the oral administration of 1.5 and 3 g of clotrimazole produced mean peak concentrations in the serum of 1.16 and 1.29 mug/ml, respectively, 2 hr after administration. In six patients taking 1.5 g of clotrimazole every 6 hr, there was a progressive decline in the serum concentrations after administration of a dose on days 1, 4, and 8. Nine other patients begun on a similar schedule manifested gastrointestinal symptoms attributed to the clotrimazole and were unable to complete the study. Concentrations of active drug in the urine were less than 1% of the administered dose.

Laboratory assessment of the antimycotic drug clotrimazole

Laboratory studies on clotrimazole showed that it had marked activity in vitro against all the Candida spp. and Cryptococcus spp. tested, against almost all strains of dermatophytes, and against Aspergillus spp and other fungal genera responsible for systemic mycoses; it had limited activity towards Gram-positive bacteria. The majority of Candida strains required MICs below 1 mug/ml and MCCs below 2 mug/ml.Serum, urine, and faecal assays of clotrimazole were made by microbiological methods on five children who received 100 mg/kg/day clotrimazole for several weeks. In-vitro sensitivity tests and biological fluid drug assays are also reported on specimens from 18 patients in other hospitals receiving clotrimazole for severe candidosis; several were renal transplant cases. Similar investigations are reported on specimens from 18 patients with pulmonary aspergilloses. The significance of low levels of the drug in body fluids, even after prolonged therapy, is discussed, and it is suggested that clotrimazole may be the first of a long series of imidazole derivatives with varying pharmacological and therapeutic properties.

Pulmonary aspergillomata in a child treated with clotrimazole

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Chemotherapeutic evaluation of clotrimazole (Bay b 5097, 1 (o-chloro- - -diphenylbenzyl) imidazole)

Clotrimazole has a broad spectrum of activity against yeast and filamentous fungi in vitro and also in vivo when given orally or parenterally to experimentally infected mice and when administered orally or topically to infected guinea pigs. In vitro a distinct inoculum effect has been observed with a number of strains of Candida and Torulopsis; minimal inhibitory concentrations have tended to increase with increased incubation time. With prolonged incubation times, resistance can be developed to clotrimazole in vitro, but this resistance is readily reversible upon passage in drug-free broth. The degree of in vivo activity of clotrimazole against Candida depends on the severity of infection used. Orally it appears to be more effective when administered by gavage than when given mixed in the diet. Pretreatment with the agent may decrease its efficacy because of drug inactivation. Against dermatophytes, clotrimazole has a degree of activity similar to griseofulvin when given orally, but it is less active than tolnaftate topically in cutaneous infection of Trichophyton mentagrophytes in guinea pigs. In vitro, but not in vivo, some gram-positive and gram-negative bacteria are inhibited by low concentrations of clotrimazole.

In vitro antifungal activity of clotrimazole (Bay b 5097)

The in vitro antifungal activity of clotrimazole (Bay b 5097) was compared with those of amphotericin B, griseofulvin, nystatin, and pyrrolnitrin. The inhibitory activity of clotrimazole against most systemic pathogens was comparable to that of amphotericin B; minimal inhibitory concentrations of the two drugs for Blastomyces dermatitidis, Histoplasma capsulatum, Sporothrix schenckii, Cryptococcus neoformans, and Coccidioides immitis were in the range of 0.20 to 3.13 and 0.10 to 6.25 mug/ml, respectively. One isolate of Allescheria boydii was resistant to 100 mug of amphotericin B per ml but was inhibited by 6.25 mug of clotrimazole per ml. Clotrimazole was less active than amphotericin B against Candida albicans and Aspergillus fumigatus. The activity of clotrimazole against dermatophytes was comparable to that of pyrrolnitrin; 0.78 mug of either compound per ml was fungicidal for most isolates of Trichophyton sp., Microsporum sp. and Epidermophyton floccosum. Both griseofulvin and nystatin were less active than clotrimazole. The size of inoculum was shown to have a significant effect on the results of in vitro susceptibility testing with clotrimazole.