Megestrol acetate research from PubMed - chart

Ref #	# cats	Age /sex of cat	Reason Prescribed MA	Dosage & length of treatment w/ MA	Side effects
2	1 cat	12 year old Intact female Siamese	Birth control	Dosage not given – given intermittently over 10 years	Benign growths in uterus
3	Number of cats not given	Not given	Not given	Dosage not given	Survey of insured pet owners. Diabetes occurred in 1 of 230 cats in survey – noted that male cats treated with MA had “significantly higher risk ” for diabetes.
5	1 cat	1.5 year old male	Chin sores	See ‘Side Effects” column. MA info. in blue Other meds in black Symptoms in green Symptoms after MA treatment in bold green Time line in yellow	Prescribed topical cleansing; oral orbifloxacin  2.2 mg/kg bodyweight  daily for 14 days and oral prednisone (generic), 1 mg/kg BW daily for 4 days. Day 30 - Same sore – two more methylprednisolone acetate  4 mg/kg BW, sub q administered. A hypoallergenic food trial was commenced. Day 38 still had sores – returned to vet Prescribed megestrol acetate 1 mg/kg BW  daily  for 5 days, and then 0.5 mg/kg BW twice weekly for 21 days. prescription was refilled 33 days later, so that the cat received 1 mg/kg BW for 2 days followed by 0.5 mg/kg BW, for 16 days Day 96 –(58 days after MA prescribed) returned All 6 breasts swollen Mastectomy of right mammary gland and biopsy of right groin lymph node. Right gland showed benign fibrous tumor and neutrophils (white blood cells indicating infection) suggesting breast infection. The right groin lymph node had no microscopic organ or tissue damage. Rechecked 10 d (day 106) and 15 d (day 111) after surgery, that is, 68 d and 73 d after initiation of MA treatment. Rest of mammary glands had regressed slightly, but the left groin mammary gland had enlarged slightly. Came in 7 d later  (day 118)for inappetence (80 d after initiation of megestrol acetate treatment). Temperature slightly above normal and 5% dehydrated. Another chin sore. Left groin mammary gland was ulcerated, swollen, warm, painful to touch, and asymmetrically enlarged to 4 cm in diameter. A CBC count showed a mild leukocytosis (increased white blood cells) and mild neutrophilia (increased white blood cells.) A presumptive diagnosis of superficial mastitis (breast infection) was made. The cat received trimethoprim-sulfadiazine, 35 mg/kg BW, Sub q 1X daily for  3 days, and sub q  meloxicam , 0.02 mg/kg BW, and lactated Ringer's solution, 60 to 120 mL, 1X daily  for the next 3 days. Temperature returned to normal. When the cat's skin lesions returned the owner did not wish to pursue further diagnostic tests and elected to euthanize the cat. A necropsy was not performed.

 

11	8 cats	Not given	Eye infection	Dosage not given	None Reported – successfully treated infection
1212 12	17 pre-pubescent spayed/neutered kittens in study 5 ---------> 5 ----------->	Spayed/ neutered kittens Spayed/ neutered kittens	Study	5 mg 2X a week for 12 or 13 weeks  then 2.5 mg 1X week for 12 weeks then no ma for 12 weeks 15  mg 2X a week for 12 or 13 weeks then 2.5 mg 1X week for 12 weeks then no ma for 12 weeks	Uterine horns increased in length and diameter. Endometrium became deeply folded. Enlargement of glandular epithelium and production of glycogen by the glandular cells. One cat developed pyometra. During 12 weeks without ma proliferate d endometrium regressed considerably 1 case pyometra
	5 -----------> 2 ----------->	Spayed/ Neutered kittens kittens		No treatment – served as controls 2.5  mg weekly for 6 weeks	“Sufficient to induce similar changes”   - - not clear if author was referring to changes during 24 weeks with ma or 12 weeks without.

 

14	17  cats treated with MA were compared to 97 cats  not treated  with MA	Sex and age not given	Not given	2.5 – 5 mg daily  - treatment length varied	Tissue analysis 14 benign growths 3 cancerous growths Scientific discussion beyond my grasp
17	Number of cats not given	Sex and age not given	Study	“high doses” for 12 months	“The results of this study demonstrate that administration of megestrol acetate to cats can produce a state of moderate to severe glucose intolerance, which is usually reversible after cessation of treatment.
18	14 cats total 7 received MA 7 received prednisone 3 received nothing	Sex and age not given	Study of “adrenal cortisol response to exogenous adrenocortic-otrophic hormone” at doses equal to those used for skin conditions	7 received 5 mg MA daily for 16 days 7 received prednisolone 2mg/kg daily for 16 days 3 cats received no medications and served as controls	Suppression cortisol levels day 8 both ma and prednisolone treated cats Day 15 more marked change in MA recipients vs. prednisolone recipients Day 30 Recovery of adrenal reserve present in 6 of 7 cats given prednisolone, but in only 3 of 7 receiving MA. Decrease in Eosinophils (white blood cells), excess sugar in urine and liver cell swelling from glycogen deposition were occasionally recorded in treated cats of both groups.

 

19	6 cats	Sex and age not given	Study	5 mg daily for 8 days On separate occasion given prednisolone @2 mg/kg of body weight/day for 8 days –  time	The drugs induced similar increases in fasting blood glucose concentrations and decreases in glucose excretion rates in the cats. Usually, each cat developed reduced tolerance of an IV glucose load; concomitant fasting hyperglycemia occurred in 3 cats after prednisolone therapy, and in 1 of these 3 cats after megestrol acetate
22	13 cats	Sex and age not given	Insulin therapy in cats with  diabetes	Dosage and length of treatment not given	3 developed diabetes after MA therapy. 2 got insulin and the diabetes reversed, one received no drug treatment and the diabetes reversed.
23	21 cats	Sex and age not given	Skin problems	5 mg per cat per day for 7 days then 5 mg every 3 days for 21 days	Side effects encountered were increased appetite, personality changes and depression. In all cats, a good improvement of the lesions was noted as soon as treatment was started. In 25% of the patients, one treatment schedule was sufficient to control the skin disease for at least 18 months. In the remaining 75%, two treatment schedules and/or a maintenance dosage had to be established

 

24

20 cats total 16 received MA 4 received no medication and served as controls

Sex and age not given

Study of adrenocortical suppression in cats given MA

8 cats at a dose of 2.5 mg every other day for 2 weeks 8 cats at  5.0 mg every day for 2 weeks 4 cats rec’d no No treatment  for 2 weeks and served as controls Cats were restrained with acepromazine maleate and ketamine hydrochloride during blood sample collection and large-dose glucose infusion

Each week 1 control cat and 2 cats from each group was euthanized and analyzed. Significant impairment of adrenocortical function and alteration of adrenocortical morphology occurred with both treated groups. The most severe adrenocortical alterations occurred in the cats 1 week after megestrol acetate was no longer given (i.e., experiment week 3). Megestrol acetate-induced adrenocortical suppression contributed to the death of 1 cat. It was concluded that if stress occurs to cats on treatment or soon after treatment with megestrol acetate, glucocorticoids should be supplemented. The effects of megestrol acetate on glucose tolerance were overshadowed by the unforeseen intolerance caused by chemical restraint with acepromazine maleate and ketamine hydrochloride.

 

27	1 cat 1 cat 1 cat	18 year old  neutered male 10 year old neutered male 3 year old neutered male	Skin problems Skin problems Skin problems	5 mg every other day for 2 weeks Initially treated with 30 mg methlylprednisolone acetate4 intramuscularly. Two months later he was treated with 5 mg megestrol acetate on alternate days - period of time not given See “Side Effects” column MA in blue Other med’s in black Symptoms in green Symptoms post MA in bold green	Previous history of diabetes that had reversed one year prior –previous corticosteroid treatment. After MA developed high blood sugar –was treated but died Excessive thirst, excessive dilute urine, excessive appetite and weight loss appeared within ten days. The cat was stabilized on insulin and megestrol acetate therapy was continued. Within a month, signs of high blood sugar appeared and therapy was stopped. The cat has remained normal since. Intralesional injection of 20 mg methlylprednisolone acetate. When the lesion didn’t heal, surgical excision was performed. When the granuloma recurred, the cat received 2.5 mg prednisone5 daily and 100 mg chloramphenicol ' daily. One week later, surgical excision was again attempted and when this failed, the cat was treated with 5 mg MA on alternate days. The lesion was also injected with 0.4 cc triamcinolone. The treatment was repeated two weeks later and the MA continued. The cat was admitted again after two weeks for excessive urination, excessive thirst and an elevated temperature of 40.30C. The cat was stabilized with insulin and megestrol acetate therapy was discontinued. The insulin dose was gradually reduced over ten days and the cat is doing well.
31	244 cats	Sex and age not given	Birth control	2.5 mg weekly for 30 weeks	No pregnancies – 21 showed heat signs – Side effects were increased appetite, weight increase and changes of temperament were the most pronounced. One cat developed pyometra after three years of treatment with the preparation. Oslo 1974 Pyometra 1 in 244 = .4%
33	9 cats	3 intact 6-8 month pregnant  females 1 intact  “aged”  pregnant female 2 neutered males age not given 3 spayed females age not given	Birth control?    Birth Control?    Skin problems    Skin problems	Dosage and treatment length not given  Dosage and treatment length not given Dosage not given – treatment for 14 months to 5 years Dosage not given – treatment for 14 months to 5 years	Enlarged mammary glands – cat was spayed – returned to normal  Enlarged mammary glands – cat was spayed – returned to normal Enlarged mammary glands – lesions excised – no recurrence during follow up period Enlarged mammary glands – lesions excised – no recurrence during follow up period