Source: FDA, National Drug Code (US) Revision Year: 2021
Diazoxide administered orally produces a prompt dose-related increase in blood glucose level, due primarily to an inhibition of insulin release from the pancreas, and also to an extrapancreatic effect.
The hyperglycemic effect begins within an hour and generally lasts no more than eight hours in the presence of normal renal function.
PROGLYCEM decreases the excretion of sodium and water, resulting in fluid retention which may be clinically significant.
The hypotensive effect of diazoxide on blood pressure is usually not marked with the oral preparation. This contrasts with the intravenous preparation of diazoxide (see ADVERSE REACTIONS).
Other pharmacologic actions of PROGLYCEM include increased pulse rate; increased serum uric acid levels due to decreased excretion; increased serum levels of free fatty acids' decreased chloride excretion; decreased para-aminohippuric acid; (PAH) clearance with no appreciable effect on glomerular filtration rate.
The concomitant administration of a benzothiazide diuretic may intensify the hyperglycemic and hyperuricemic effects of PROGLYCEM. In the presence of hypokalemia, hyperglycemic effects are also potentiated.
PROGLYCEM-induced hyperglycemia is reversed by the administration of insulin or tolbutamide. The inhibition of insulin release by PROGLYCEM is antagonized by alpha-adrenergic blocking agents.
PROGLYCEM is extensively bound (more than 90%) to serum proteins, and is excreted in the kidneys. The plasma half-life following I.V. administration is 28 ± 8.3 hours. Limited data on oral administration revealed a half-life of 24 and 36 hours in two adults. In four children aged four months to six years, the plasma half-life varied from 9.5 to 24 hours on long-term oral administration. The half-life may be prolonged following overdosage, and in patients with impaired renal function.
No long-term animal dosing study has been done to evaluate the carcinogenic potential of diazoxide. No laboratory study of mutagenic potential or animal study of effects on fertility has been done.
Reproduction studies using the oral preparation in rats have revealed increased fetal resorptions and delayed parturition, as well as fetal skeletal anomalies; evidence of skeletal and cardiac teratogenic effects in rabbits has been noted with intravenous administration. The drug has also been demonstrated to cross the placental barrier in animals and to cause degeneration of the fetal pancreatic beta cells (See ANIMAL PHARMACOLOGY AND/OR TOXICOLOGY). Since there are no adequate data on fetal effects of this drug when given to pregnant women, safety in pregnancy has not been established. When the use of PROGLYCEM is considered, the indications should be limited to those specified above for adults (See INDICATIONS AND USAGE), and the potential benefits to the mother must be weighed against possible harmful effects to the fetus.
Oral diazoxide in the mouse, rat, rabbit, dog, pig, and monkey produces a rapid and transient rise in blood glucose levels. In dogs, increased blood glucose is accompanied by increased free fatty acids, lactate, and pyruvate in the serum. In mice, a marked decrease in liver glycogen and an increase in the blood urea nitrogen level occur.
In acute toxicity studies the LD50 for oral diazoxide suspension is >5000 mg/kg in the rat, >522 mg/kg in the neonatal rat, between 1900 and 2572 mg/kg in the mouse, and 219 mg/kg in the guinea pig. Although the oral LD50 was not determined in the dog, a dosage of up to 500 mg/kg was well tolerated.
In subacute oral toxicity studies, diazoxide at 400 mg/kg in the rat produced growth retardation, edema, increases in liver and kidney weights, and adrenal hypertrophy. Daily dosages up to 1080 mg/kg for three months produced hyperglycemia, an increase in liver weight and an increase in mortality. In dogs given oral diazoxide at approximately 40 mg/kg/day for one month, no biologically significant gross or microscopic abnormalities were observed. Cataracts, attributed to markedly disturbed carbohydrate metabolism, have been observed in a few dogs given repeated daily doses of oral or intravenous diazoxide. The lenticular changes resembled those which occur experimentally in animals with increased blood glucose levels. In chronic toxicity studies, rats given a daily dose of 200 mg/kg diazoxide for 52 weeks had a decrease in weight gain and an increase in heart, liver, adrenal and thyroid weights. Mortality in drug-treated and control groups was not different. Dogs treated with diazoxide at dosages of 50, 100, and 200 mg/kg/day for 82 weeks had higher blood glucose levels than controls. Mild bone marrow stimulation and increased pancreas weights were evident in the drug-treated dogs; several developed inguinal hernias, one had a testicular seminoma, and another had a mass near the penis. Two females had inguinal mammary swellings. The etiology of these changes was not established. There was no difference in mortality between drug-treated and control groups. In a second chronic oral toxicity study, dogs given milled diazoxide at 50, 100, and 200 mg/kg/day had anorexia and severe weight loss, causing death in a few. Hematologic, biochemical, and histologic examination did not indicate any cause of death other than inanition. After one year of treatment, there is no evidence of herniation or tissue swelling in any of the dogs.
When diazoxide was administered at high dosages concomitantly with either chlorothiazide to rats or trichlormethiazide to dogs, increased toxicity was observed. In rats, the combination was nephrotoxic; epithelial hyperplasia was observed in the collecting tubules. In dogs, a diabetic syndrome was produced which resulted in ketosis and death. Neither of the drugs given alone produced these effects.
Although the data are inconclusive, reproduction and teratology studies in several species of animals indicate that diazoxide, when administered during the critical period of embryo formation, may interfere with normal fetal development, possibly through altered glucose metabolism. Parturition was occasionally prolonged in animals treated at term. Intravenous administration of diazoxide to pregnant sheep, goats, and swine produced in the fetus an appreciable increase in blood glucose level and degeneration of the beta cells of the Islets of Langerhans. The reversibility of these effects was not studied.
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