fosfomycin and Hearing-Loss--Sensorineural

Cis-diamminedichloroplatinum II (cisplatin), a divalent platinum compound and potent cell-cycle nonspecific chemotherapeutic agent, produces a dose-limiting, permanent, high-frequency sensori-neural hearing loss and peripheral neuropathy, and a dose-related cumulative renal insufficiency with tubular necrosis and interstitial nephritis. The potential for dose-limiting and permanent cochlear (neuro) toxicity remains despite present methods of hypertonic saline, prehydration, and mannitol diuresis prior to drug administration. The exact mechanism(s) of ototoxicity and/or nephrotoxicity are still unknown. Continued aggressive high-dose cisplatin chemotherapy necessitates the investigation of ways to decrease the dose-limiting side effects that inhibit the administration of cisplatin at therapeutic and tumoricidal doses. This multifaceted project investigates two categories of potential inhibitors of cisplatin toxicity that, when coadministered with a known tumoricidal and ototoxic dose of cisplatin, will decrease or inhibit the ototoxicity: 1. phosphonic acid antibiotics (fosfomycin; 1,2 epoxypropylphosphonic acid); 2. nonglucocorticoid 21-aminosteroids, which are free oxygen radical scavengers (LAZAROIDS: U74006F and U78517F). This project also investigates the role of pigmentation as a variable affecting the evaluation of platinum-induced ototoxicity in the guinea pig animal model. Identification of an optimal animal model for future cisplatin toxicity research should be based on previously established species-specific differences in total drug dose, systemic toxicity, and morphological and functional evidence of cochlear toxicity, as affected by differences in pigmentation and drug tolerance. Cytocochleography, brainstem auditory evoked response (BSER), scanning and transmission electron microscopy of organ of Corti and the stria vascularis, double-blind light microscopy of renal, small intestine, and peripheral nerve tissue, and gamma-emission analysis of 195Mplatinum localization in inner ear neuroepithelium and the stria vascularis are used in the global evaluation of the ototoxic effects of cisplatin in both the adult albino and pigmented guinea pig.

Topics: Albinism; Animals; Chromans; Cisplatin; Cochlea; Dose-Response Relationship, Drug; Evoked Potentials, Auditory, Brain Stem; Fosfomycin; Free Radical Scavengers; Guinea Pigs; Hair Cells, Auditory; Hearing Loss, Sensorineural; Humans; Intestine, Small; Kidney; Lipid Peroxides; Melanins; Piperazines; Pregnatrienes; Sciatic Nerve; Skin Pigmentation

This study investigates the effect of fosfomycin on the tumoricidal efficacy of cisplatinum.. Prospective study utilizing the FaDu squamous cell carcinoma cell line and a nude mouse tumor xenograft model.. Tumor cell growth was assessed in vitro in the presence of cisplatinum and/or fosfomycin utilizing the MTT assay. An optimal cisplatinum dose and dosing schedule was established in a nude mouse tumor xenograft model of squamous cell carcinoma. Using this model, fosfomycin was tested at three dosages and tumor growth monitored over 4 weeks.. Mice treated with cisplatinum and fosfomycin had smaller tumors than those treated with cisplatinum alone (P<.01).. This study is the first demonstration that fosfomycin does not inhibit the tumoricidal efficacy of cisplatinum in vivo. This suggests that fosfomycin may be useful in preventing cisplatinum-induced ototoxicity and nephrotoxicity in humans without altering the tumor response rate.

Topics: Animals; Anti-Bacterial Agents; Carcinoma, Squamous Cell; Cisplatin; Dose-Response Relationship, Drug; Drug Administration Schedule; Drug Interactions; Fosfomycin; Hearing Loss, Sensorineural; Kidney Diseases; Mice; Mice, Inbred BALB C; Mice, Nude; Prospective Studies; Tumor Cells, Cultured

The efficacies of four agents in ameliorating cisplatin-induced ototoxicity were investigated. Hamsters were given a series of 5 cisplatin injections (3 mg/kg/injection once every other day, i.p.) either alone or in combination with 1600 mg/kg/injection sodium thiosulfate (STS), 300 mg/kg/injection diethyldithiocarbamate (DDTC), 18 mg/kg/injection WR-2721, or 300 mg/kg/injection fosfomycin (n = 10/group). Ototoxicity was assessed electrophysiologically by auditory brainstem responses (ABRs) and anatomically by cochlear histology. The greatest auditory protection was given by STS, followed by DDTC. WR-2721 and fosfomycin did not provide any protection. All of the animals in the STS and DDTC groups survived, while some fatalities occurred in the fosfomycin, WR-2721, and cisplatin-only groups. Thus, the agents that were protective against ototoxicity were also protective against mortality. The ABRs also provided evidence of cisplatin-induced neuropathy. In summary, STS and DDTC hold promise for ameliorating the ototoxic effects of cisplatin chemotherapy and the hamster proved to be an excellent model of cisplatin ototoxicity.

Topics: Amifostine; Animals; Anti-Bacterial Agents; Antidotes; Antineoplastic Agents; Auditory Threshold; Cisplatin; Cochlea; Cricetinae; Ditiocarb; Drug Interactions; Electrophysiology; Evoked Potentials, Auditory, Brain Stem; Fosfomycin; Hair Cells, Auditory; Hearing Loss, Sensorineural; Injections, Intraperitoneal; Male; Mesocricetus; Microscopy, Electron, Scanning; Radiation-Protective Agents; Random Allocation; Thiosulfates

The continued chemotherapeutic application of cisplatin (cis-diamminedichloroplatinum [II]) necessitates reduction of its dose-limiting toxicity without decreasing its tumoricidal effect. This research project evaluated the efficacy of fosfomycin, a phosphonic acid antibiotic, in decreasing or ameliorating the ototoxicity (high frequency sensorineural hearing loss) and nephrotoxicity (renal tubular necrosis and interstitial nephritis) of cisplatin. Experimentally, fosfomycin effectively inhibits aminoglycoside-induced ototoxicity and nephrotoxicity in animals and humans. The efficacy of fosfomycin in blocking platinum-induced toxicity in the guinea pig was evaluated histologically and functionally using cytocochleography and light microscopy of the organ of Corti and the auditory brain stem evoked response (ABR), and light microscopy of renal corticomedullary tissues, small bowel, liver, lung, and peripheral nerve. The results demonstrate that fosfomycin ameliorates the acute renal tubular necrosis and interstitial nephritis and markedly inhibits the elevation of ABR thresholds and simultaneous outer hair cell loss that can result from cisplatinum administration. Fosfomycin should be considered a potential antidote for the dose-limiting ototoxicity and nephrotoxicity of cisplatin chemotherapy.

Topics: Acute Kidney Injury; Animals; Cisplatin; Evoked Potentials, Auditory; Fosfomycin; Guinea Pigs; Hearing Loss, Sensorineural; Kidney; Kidney Tubular Necrosis, Acute; Nephritis, Interstitial