Diazoxide

DIAZOXIDE- diazoxide suspension
Par Pharmaceutical, Inc

DESCRIPTION

Diazoxide Oral Suspension, USP is a nondiuretic benzothiadiazine derivative taken orally for the management of symptomatic hypoglycemia. The suspension contains 50 mg of diazoxide, USP in each milliliter and has a chocolate-mint flavor; alcohol content is approximately 7.29%. Other ingredients: Sorbitol solution, chocolate mint type flavor, propylene glycol, magnesium aluminum silicate, carboxymethycellulose sodium, sodium benzoate, methylparaben, poloxamer 188, propylparaben, FD&C Red No. 40, FD&C Yellow No. 6 and purified water. Hydrochloric acid may be added to adjust pH.

Diazoxide has the following structural formula:

structure

Diazoxide is 7-chloro-3-methyl-2H -1,2,4-benzothiadiazine 1,1-dioxide with the empirical formula C8 H7 CIN2 O2 S and the molecular weight 230.7. It is a white powder practically insoluble to sparingly soluble in water.

CLINICAL PHARMACOLOGY


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.

Diazoxide 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 diazoxide 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 diazoxide. In the presence of hypokalemia, hyperglycemic effects are also potentiated.

Diazoxide-induced hyperglycemia is reversed by the administration of insulin or tolbutamide. The inhibition of insulin release by diazoxide is antagonized by alpha-adrenergic blocking agents.

Diazoxide 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.

INDICATIONS & USAGE

Diazoxide oral suspension is useful in the management of hypoglycemia due to hyperinsulinism associated with the following conditions:

Adults: Inoperable islet cell adenoma or carcinoma, or extrapancreatic malignancy.

Infants and Children: Leucine sensitivity, islet cell hyperplasia, nesidioblastosis, extrapancreatic malignancy, islet cell adenoma, or adenomatosis. Diazoxide oral suspension may be used preoperatively as a temporary measure, and postoperatively, if hypoglycemia persists.

Diazoxide oral suspension should be used only after a diagnosis of hypoglycemia due to one of the above conditions has been definitely established. When other specific medical therapy or surgical management either has been unsuccessful or is not feasible, treatment with diazoxide oral suspension should be considered.

CONTRAINDICATIONS

The use of diazoxide oral suspension for functional hypoglycemia is contraindicated. The drug should not be used in patients hypersensitive to diazoxide or to other thiazides unless the potential benefits outweigh the possible risks.

WARNINGS

The antidiuretic property of diazoxide may lead to significant fluid retention, which in patients with compromised cardiac reserve, may precipitate congestive heart failure. The fluid retention will respond to conventional therapy with diuretics.

It should be noted that concomitantly administered thiazides may potentiate the hyperglycemic and hyperuricemic actions of diazoxide (See DRUG INTERACTIONS and ANIMAL PHARMACOLOGY AND/OR TOXICOLOGY).

Ketoacidosis and nonketotic hyperosmolar coma have been reported in patients treated with recommended doses of diazoxide oral suspension usually during intercurrent illness. Prompt recognition and treatment are essential (See OVERDOSAGE), and prolonged surveillance following the acute episode is necessary because of the long drug half-life of approximately 30 hours. The occurrence of these serious events may be reduced by careful education of patients regarding the need for monitoring the urine for sugar and ketones and for prompt reporting of abnormal findings and unusual symptoms to the physician. Transient cataracts occurred in association with hyperosmolar coma in an infant, and subsided on correction of the hyper-osmolarity. Cataracts have been observed in several animals receiving daily doses of intravenous or oral diazoxide.

The development of abnormal facial features in four children treated chronically (>4 years) with diazoxide oral suspension for hypoglycemia hyperinsulinism in the same clinic has been reported.

Pulmonary Hypertension in Neonates and Infants

There have been postmarketing reports of pulmonary hypertension occurring in infants and neonates treated with diazoxide. The cases were reversible upon discontinuation of the drug. Monitor patients, especially those with risk factors for pulmonary hypertension, for respiratory distress and discontinue diazoxide if pulmonary hypertension is suspected.

PRECAUTIONS

GENERAL PRECAUTIONS

Treatment with diazoxide oral suspension should be initiated under close clinical supervision, with careful monitoring of blood glucose and clinical response until the patient’s condition has stabilized. This usually requires several days. If not effective in two to three weeks, the drug should be discontinued.

Prolonged treatment requires regular monitoring of the urine for sugar and ketones, especially under stress conditions, with prompt reporting of any abnormalities to the physician. Additionally, blood sugar levels should be monitored periodically by the physician to determine the need for dose adjustment.

The effects of diazoxide on the hematopoietic system and the level of serum uric acid should be kept in mind; the latter should be considered particularly in patients with hyperuricemia or a history of gout.

In some patients, higher blood levels have been observed with the oral suspension than with the capsule formulation of diazoxide. Dosage should be adjusted as necessary in individual patients if changed from one formulation to the other.

Since the plasma half-life of diazoxide is prolonged in patients with impaired renal function, a reduced dosage should be considered. Serum electrolyte levels should also be evaluated for such patients.

The antihypertensive effect of other drugs may be enhanced by diazoxide oral suspension and this should be kept in mind when administering it concomitantly with antihypertensive agents.

Because of the protein binding, administration of diazoxide oral suspension with coumarin or its derivatives may require reduction in the dosage of the anticoagulant, although there has been no reported evidence of excessive anticoagulant effect. In addition, diazoxide may possibly displace bilirubin from albumin; this should be kept in mind particularly when treating newborns with increased bilirubinemia.

Pulmonary hypertension has been reported in neonates and young infants treated with diazoxide. (see WARNINGS)

INFORMATION FOR PATIENTS

During treatment with diazoxide oral suspension the patient should be advised to consult regularly with the physician and to cooperate in the periodic monitoring of his condition by laboratory tests. In addition, the patient should be advised:

  • to take the drug on a regular schedule as prescribed, not to skip doses, not to take extra doses;
  • not to use this drug with other medications unless this is done with the physician’s advice;
  • not to allow anyone else to take this medication;
  • to follow dietary instructions;
  • to report promptly any adverse effects (i.e., increased urinary frequency, increased thirst, fruity breath odor);
  • to report pregnancy or to discuss plans for pregnancy.

LABORATORY TESTS

The following procedures may be especially important in patient monitoring (not necessarily inclusive); blood glucose determinations (recommended at periodic intervals in patients taking diazoxide orally for treatment of hypoglycemia, until stabilized); blood urea nitrogen (BUN) determinations and creatinine clearance determinations; hematocrit determinations; platelet count determinations; total and differential leukocyte counts; serum aspartate aminotransferase (AST) level determinations; serum uric acid level determinations; and urine testing for glucose and ketones (in patients being treated with diazoxide for hypoglycemia, semiquantitative estimation of sugar and ketones in serum performed by the patient and reported to the physician provides frequent and relatively inexpensive monitoring of the condition).

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