Diazoxide

, Parenteral

Pronunciation: DIE-aze-OX-ide
Class: Agent for hypertensive emergencies

Trade Names:
Hyperstat IV
- Injection 15 mg/mL

Pharmacology

Relaxes smooth muscle in peripheral arterioles, thus reducing BP.

Pharmacokinetics

Distribution

Greater than 90% protein bound. Crosses placenta.

Elimination

t ½ approximately 28 h.

Onset

1 min.

Peak

2 to 5 min.

Duration

Less than 12 h.

Indications and Usage

Short-term emergency reduction of BP in severe, nonmalignant, and malignant hypertension in hospitalized patients.

Contraindications

Dissecting aortic aneurysm; hypersensitivity to thiazides or other sulfonamide derivatives; treatment of compensatory hypertension, such as that associated with aortic coarctation or arteriovenous shunt. Diazoxide is ineffective against hypertension caused by pheochromocytoma.

Dosage and Administration

Adults

IV 1 to 3 mg/kg (max 150 mg in single injection) by rapid injection (no longer than 30 sec). May repeat at 5 to 15 min intervals until satisfactory reduction in BP. May repeat at intervals of 4 to 24 h until oral therapy can be initiated. Do not use for longer than 10 days. Have patient remain supine during IV administration.

Storage/Stability

Protect from light/freezing. Store between 2° to 30°C (36° to 86°F).

Drug Interactions

Antihypertensive agents

Enhanced antihypertensive effect.

Highly protein-bound agents

Higher blood levels of these agents may occur as a result of displacement by diazoxide.

Hydantoins

Possible loss of seizure control.

Sulfonylureas

Hyperglycemia may occur.

Thiazide diuretics

May increase hyperuricemic, hyperglycemic, and antihypertensive effects of diazoxide.

Laboratory Test Interactions

Hyperglycemia and hyperuricemia produced by diazoxide may affect assessment of these metabolic states. Increased renin secretion and IgG concentrations and decreased cortisol secretion may occur. May cause false-negative insulin response to glucagon.

Adverse Reactions

Cardiovascular

Sodium and water retention; hypotension to shock levels; CHF; edema; myocardial ischemia (eg, angina, arrhythmias, ECG changes); supraventricular tachycardia; palpitations; bradycardia.

CNS

Dizziness; weakness; cerebral ischemia; cerebral infarction (eg, unconsciousness, convulsions, paralysis, confusion, focal neurologic deficit); sweating; flushing and feelings of warmth; transient neurologic findings (eg, headache, lethargy, somnolence, euphoria, ringing in the ears, momentary hearing loss).

Dermatologic

Cellulitis or phlebitis at site of extravasation; warmth or pain along course of injected vein.

GI

Nausea; vomiting; acute pancreatitis (rare); diarrhea; abdominal discomfort.

Metabolic

Hyperglycemia; hyperosmolar coma; hyperuricemia.

Miscellaneous

Hypersensitivity reactions; papilledema.

Precautions

Pregnancy

Category C .

Lactation

Undetermined.

Special Risk Patients

Diabetic patients may need treatment for hyperglycemia. Use with care in patients with impaired cerebral or cardiac circulation in whom rapid reduction in BP might be deleterious. Observe caution when reducing severely elevated BP.

Fluid and electrolyte balance

Because of sodium and water retention, with possible edema and CHF, concomitant use of diuretic may be needed. However, thiazide diuretics may potentiate diazoxide's antihypertensive, hyperglycemic, and hyperuricemic actions.

Overdosage

Symptoms

Hypotension, hyperglycemia.

Patient Information

  • Emphasize importance of follow-up exams and blood testing to assure effectiveness and to minimize adverse reactions.
  • Tell patient to report adverse reactions to health care provider.
  • Caution patient to avoid sudden position changes to prevent orthostatic hypotension.
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