Friday, July 20, 2018

Megestrol acetate PubMed research - summary

Five studies/cases involved high blood sugar/ glucose intolerance and diabetes. One death was reported, but the cat was 18 and had a previous history of diabetes and corticosteroid treatment. Three studies/cases reported that the diabetes reversed after the MA was discontinued, sometimes with insulin therapy and sometimes without. One of the two remaining studies was a survey of insured pet owners in the UK (total number surveyed not given) and reported that the incidence of diabetes among cats in the survey was 1 in 230, but “significantly higher” among cats which had received MA.  At less than one half of one percent “significantly higher” could still be a very low number. The last study doesn’t mention if the blood sugar issue resolved after the study.

Mammary swelling and growths were also discussed. One cat, only 1.5 years old, had 121 days of treatment for a skin condition with not just MA, but a host of other drugs. After the MA treatment the cat experienced mammary swelling and although that resolved, when the skin condition returned, the owner elected to euthanize the cat. In another study, nine cats had enlarged mammary glands. Four were spayed and the swelling went away, and in the other five the lesions were excised and did not return during the follow up period. Finally, the tissue of 17 cats treated with MA and with mammary growths was analyzed. Fourteen were benign, three were cancerous.

Two studies involved “adrenocortical function” and even with a medical dictionary much of it was over my head. The first studied 20 cats, 16 of which received MA and 4 of which served as controls, concluded that “the effects of megestrol acetate on glucose tolerance were overshadowed by the unforeseen intolerance caused by chemical restraint with acepromazine maleate and ketamine hydrochloride.” The second study had 7 cats which received MA and 7 cats which received Prednisolone for 16 days and were observed for 30. It stated that on day 8 both groups had suppressed cortisol levels, on day 15 the MA group had more marked changes, and by day 30, 6 of 7 cats receiving prednisolone had recovered their adrenal reserves, but only 3 of 7 receiving MA had. Other side effects were “occasionally noted in both groups”.

Three studies/cases either studied or reported changes in the uterus of cats receiving MA. In 1974 in Oslo, 244 cats were given 2.5mg of MA for 30 weeks by their owners to study its use as a birth control. There were no pregnancies but one cat who received the MA for three years developed Pyometra. Another study dosed spayed kittens for 12 weeks then observed them for another 12 weeks.  It doesn’t give the number, but some had uterine horns increase in length and diameter, folds in the endometrium, and one kitten developed pyometra. The third case was of an intact 12 year old Siamese cat that had been on MA for 10 years intermittently as a birth control, and had developed a benign growth in the uterus.

Increased appetite, personality changes, and depression were reported in 21 cats given MA for skin issues.

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