Muscle irritation caused by different products containing oxytetracycline

Muscle irritation studies were done in rabbits using 9 different commercial products. Eight products had propylene glycol and 1 had polyvinylpyrrolidone as a vehicle. Macroscopical examination 3,6 and 10 days after intramuscular injection indicated that the irritation caused by the 8 products with propylene glycol as a vehicle were very similar. The product with polyvinylpyrrolidone caused much less damage and healing took place more quickly. Saline used as a control caused no tissue damage.