Medroxyprogesterone Acetate

By Rania Gollakner, BS, DVM, MPH

What is medroxyprogesterone acetate?

Medroxyprogesterone acetate (brand names: Provera®, Meprogest®, Proclim®) is a progestin hormone used to treat sexually driven behavior problems such as male-male aggression, spraying, roaming, and mounting in cats. In dogs, it has been used for many conditions including certain dwarfisms, skin conditions, reproductive conditions, and behaviors. In horses, it has been used for many conditions such as reproductive conditions and behaviors.

Its use in cats, dogs, and horses to treat reproductive, behavioral, and other conditions is ‘off label’ or ‘extra label’. Many drugs are commonly prescribed for off label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully as their directions may be significantly different from those on the label.

How is medroxyprogesterone acetate given?

Medroxyprogesterone acetate is given by mouth in the form of a tablet. It can also be given as an injection in the hospital setting. Give the tablet form with or without food; however, if stomach upset occurs when dosed on an empty stomach, give future doses with food.

This medication should take effect within 1 to 2 hours; however, effects may not be visibly noticeable depending on the condition being treated, and therefore laboratory tests may need to be done to evaluate this medication’s effectiveness.

What if I miss giving my pet the medication?

If you miss a dose, give it when you remember, but if it is close to the time for the next dose, skip the dose you missed and give it at the next scheduled time, and return to the regular dosing schedule. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

Side effects may include increased appetite, increased thirst, weight gain, sleepiness, or changes in personality. More serious side effects include changes to the breast tissue, diabetes, decreased thyroid hormone levels, or uterine infection.

This long-acting medication lasts for at least 4 to 6 weeks, and may last longer in pets with kidney or liver disease.

Are there any risk factors for this medication?

Do not use medroxyprogesterone acetate in pets that are allergic to it. Do not use prior to puberty, during pregnancy, 1-2 months after a heat cycle, or to treat false-pregnancy. Do not use in pets with diabetes, uterine bleeding, or in females with a prolonged heat cycle. Medroxyprogesterone acetate should be used cautiously in lactating females.

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with medroxyprogesterone acetate: corticosteroids, cyclosporine, felbamate, rifampin, selegiline, or theophylline.

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

This medication may interact with thyroid tests.

Is there any monitoring that needs to be done with this medication?

Prior to starting this medication and periodically while using this medication, your pet’s weight, mammary tissue, blood sugar levels, and adrenal gland function should be monitored. Your veterinarian may monitor your pet to be sure that the medication is working.

How do I store medroxyprogesterone acetate?

Store the tablets in a tight container at room temperature between 68°F and 77°F (20°C and 25°C ).

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.

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