Megestrol Disease Interactions

The use of progestogens, in general, is considered by manufacturers to be contraindicated in patients with active thrombophlebitis, cerebrovascular disease, or a current or past history of thromboembolic disorders. While the role of progestogens in the development of thromboembolic events associated with hormonal therapy is often unclear and thought to be secondary to that of estrogens, it may not be insignificant. Medroxyprogesterone, a common progestational agent, has been shown to produce a hypercoagulable state in high dosages. Whether or not this effect contributes to the development of thrombotic events is unknown. However, thrombophlebitis and pulmonary embolism have been reported with megestrol, an antineoplastic and progestational agent. In addition, an increased risk of nonfatal venous thrombosis has been associated with oral contraceptive combinations containing desogestrel or gestodene relative to those that contain other progestins (e.g., levonorgestrel, norethindrone), suggesting some degree of hemostatic effect by progestogens.

Estrogens and progestogens may cause fluid retention, particularly when given in high dosages or for prolonged periods. Therapy with these agents should be administered cautiously in patients who have preexisting problems with excess fluid. In addition, patients with conditions that may be adversely affected by fluid accumulation, such as asthma, epilepsy, migraine, and cardiovascular or renal dysfunction, should be observed for exacerbation of their condition during estrogen and/or progestogen therapy.

Estrogens and progestogens may cause retinal thrombosis. Oral contraceptives should be discontinued if there is unexplained partial or complete loss of vision; onset of proptosis or diplopia; papilledema; or retinal vascular lesions. Therapy with these agents should be administered cautiously in patients who have preexisting ocular problems and appropriate diagnostic and therapeutic measures should be instituted. Contact lens wearers who develop visual changes or changes in lens tolerance should be assessed by an ophthalmologist.

Megestrol, like other progestational agents, can cause glucose intolerance. In addition, it may have glucocorticoid activity. New onset diabetes and exacerbation of preexisting diabetes have been reported in association with the chronic use of megestrol. Patients with diabetes mellitus should be monitored more closely during therapy with megestrol, and adjustments made accordingly in their antidiabetic regimen.

Megestrol appears to have glucocorticoid activity and may aggravate conditions of hyperadrenocorticalism. Clinical cases of overt Cushing's syndrome and adrenal insufficiency have been reported in association with the chronic use of megestrol.