Gastrointestinal tolerability and efficacy of 2-isopropyl-5-methylphenol in the treatment of osteoarthritis in an animal model.

OBJECTIVE To evaluate the gastrointestinal (GI) tolerability and efficacy of 2-isopropyl-5-methylphenol in the treatment of osteoarthritis (OA) in a rabbit model. METHOD A study was conducted on 28 healthy male albino rabbits, aged 6-8 months, which were divided into four groups randomly. Group A was a healthy control group; group B was a diseased, untreated; group C and group D were diseased and received paracetamol and 2-isopropyl- 5-methylphenol, respectively. The study was divided into two phases. During Phase I, OA was induced in the “diseased” rabbits, using a 4% papain solution (0.2 mL) with cysteine HCl (0.1 mL) as an activator, on the first, fourth and seventh days. Development of disease was confirmed using knee X-ray analysis, estimated by the Kellgren-Lawrence (KL) scale. During Phase II, the animals in groups C and D were treated with paracetamol and 2-isopropyl- 5-methylphenol, respectively. Knee X-rays were taken at 4-week intervals and blood tests were made before and at the end of treatment, including complete blood count, renal function tests and liver function tests. The pain score was calculated using the Rabbit Grimace Scale (RGS). RESULTS The OA pain disappeared after day 4 in the groups treated for pain alleviation. Knee X-ray showed that OA was reversed and returned to KL score “0” in group D. The 2-isopropyl-5-methylphenol treatment considerably decreased the blood levels of alanine aminotransferase, aspartate aminotransferase and alkaline phosphate (p=0.001), and improved renal and liver function. CONCLUSIONS 2-isopropyl-5-methylphenol is safe and effective in the control of pain and the inhibition and reversal of OA, and is tolerated by the GI tract in the experimentally induced rabbit model. [ABSTRACT FROM AUTHOR]