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[Six-month chronic toxicity study of miporamicin in rats]
1Toxicological Research Laboratories, Toyo Jozo Co., Ltd.
Abstract:
A six-month oral toxicity test of the new macrolide antibiotic miporamicin (MPM) was carried out in male and female rats receiving the compound in feed at concentrations of 1,280, 3,200, 8,000, or 20,000 ppm. The animals were further observed for recovery for 2 months after the completion of the treatment period. 1. No death occurred at any dosage levels throughout the study period. The only notable signs observed were marginal blepharitis and aging-associated changes that were seen occasionally among the treated and control rats. There were no symptomatic changes of particular note. 2. Body weight, feed intake and water consumption data did not reveal any noticeable change. 3. The achieved test compound intake was 69 mg/kg/day for males and 82 mg/kg/day for females in the MPM-1,280 group, 176 mg/kg/day for males and 207 mg/kg/day for females in the MPM-3,200 group, 436 mg/kg/day for males and 519 mg/kg/day for females in the MPM-8,000 group, and 1,080 mg/kg/day for males and 1,280 mg/kg/day for females in the MPM-20,000 group. 4. No changes attributable to these treatments were noted in the hematological examination or serum biochemical tests. 5. Urinalysis disclosed mild changes with respect to urine volume, urinary electrolyte concentration and osmolarity. Animals recovered from all these changes during the recovery phase observation. 6. At gross pathologic examination a dose-related enlargement of the caecum was observed. The change disappeared or diminished following the 2-month recovery phase observation. 7. Organ weight analysis showed a dose-related increase of weight of the caecum. Animals recovered or abated in this respect during the 2-month recovery phase observation. 8. Histopathologic examination revealed no adverse toxicologic changes other than spontaneous or aging-associated ones. 9. No abnormalities were noted in the liver or in the kidneys as examined by electron microscopy. 10. The maximum non-effective level of MPM thus was estimated to be 20,000 ppm at which no organic damage occurred.
Insights
The macrolide antibiotic miporamicin (MPM) showed no significant toxicity in rats over six months, even at high doses. Mild, reversible changes in urine and cecum size were observed, with no lasting adverse effects.
Area of Science:
- Pharmacology and Toxicology
- Drug Safety Assessment
- Preclinical Studies
Context:
- Evaluation of novel macrolide antibiotics is crucial for expanding therapeutic options.
- Preclinical toxicity testing is a mandatory step in drug development.
- Understanding the safety profile of miporamicin (MPM) in a mammalian model is essential.
Purpose:
- To assess the oral toxicity of miporamicin (MPM) in rats following a six-month administration.
- To determine the maximum non-effective dose (MND) of MPM.
- To evaluate the reversibility of any observed toxicological effects during a two-month recovery period.
Summary:
- Rats received MPM orally for six months at doses up to 20,000 ppm. No mortality or significant clinical signs were observed. Hematology, serum biochemistry, and histopathology showed no treatment-related adverse effects. Mild, reversible changes in urinalysis and cecal parameters (enlargement and weight increase) were noted, which resolved during the recovery phase.
- The achieved compound intake varied by dose and sex, reaching up to 1,080 mg/kg/day for males and 1,280 mg/kg/day for females at the highest dose.
- The maximum non-effective level (MND) for MPM was determined to be 20,000 ppm, as no organic damage was observed at this concentration.
Impact:
- This study establishes the safety profile of miporamicin (MPM) in a rodent model, supporting its further development.
- The findings indicate that MPM is well-tolerated, with reversible effects at high oral doses.
- The identified maximum non-effective level provides a critical benchmark for future clinical safety assessments.