Le diazoxide, un activateur des canaux potassiques appartenant à la classe des benzothiadiazines, a été développé dans les années 1960 et introduit en pratique clinique pour le traitement de l'hypertension et de l'hypoglycémie. Son efficacité dans la prise en charge des hypoglycémies persistantes et sévères, notamment chez les patients atteints d'hyperinsulinisme, a été démontrée. Initialement étudié pour ses propriétés hypotensives, le diazoxide s'est révélé par la suite avoir un effet important sur les cellules bêta du pancréas, où il inhibe la sécrétion d'insuline et augmente la glycémie. Cette découverte a établi son rôle comme agent thérapeutique important dans la prise en charge des troubles hypoglycémiques.
BRAND NAMES
Proglycem – Oral diazoxide formulation used for the treatment of hyperinsulinemic hypoglycemia.
2. Hyperstat – Injectable diazoxide brand historically used for the treatment of severe hypertension
MECHANISM OF ACTION
Diazoxide acts by opening ATP-sensitive potassium (KATP) channels present in pancreatic beta cells. This causes potassium ions to move out of the cells, resulting in membrane hyperpolarization and preventing the opening of voltage-dependent calcium channels. Consequently, calcium influx into the beta cells decreases, inhibiting insulin secretion. This reduces excessive insulin release and increases blood glucose levels, making diazoxide useful in the treatment of hyperinsulinemic hypoglycemia and congenital hyperinsulinism.
PHARMACOKINETICS
Absorption
Diazoxide is well absorbed following oral administration, with peak plasma concentrations generally reached within 2–3 hours. It has good gastrointestinal absorption, and its oral bioavailability supports its use in the treatment of hyperinsulinemic hypoglycemia. Food may influence the rate of absorption, but it does not significantly affect its overall therapeutic effectiveness.
Distribution
Diazoxide is widely distributed throughout the body and binds approximately 90% of plasma proteins, mainly albumin. It crosses the placental barrier and is distributed into breast milk. It also reaches the systemic circulation and pancreatic tissues, where it produces its therapeutic effect by inhibiting insulin secretion.
Metabolism
Diazoxide undergoes limited hepatic metabolism, with a significant proportion of the administered drug remaining unchanged in the body. It is primarily metabolized in the liver through oxidation and conjugation reactions. Its metabolism is relatively slow, contributing to its prolonged duration of action.
Elimination
Diazoxide is eliminated primarily through the kidneys via urine, with a significant proportion excreted unchanged. Its elimination half-life is approximately 24–36 hours in adults but may vary depending on renal function. Reduced kidney function can prolong drug elimination, increasing the risk of accumulation and adverse effects.
PHARMACODYNAMICS
Diazoxide is a potassium channel opener that produces its therapeutic effect by activating ATP-sensitive potassium (KATP) channels in pancreatic beta cells. This causes membrane hyperpolarization, reduces calcium influx and inhibits insulin secretion, thereby increasing blood glucose levels. It also produces vasodilation by relaxing vascular smooth muscles, which reduces peripheral vascular resistance and lowers blood pressure. Its main therapeutic use is the management of hyperinsulinemic hypoglycemia, particularly congenital hyperinsulinism.
ADMINISTRATION
Diazoxide is primarily administered orally in the form of capsules or oral suspension for the treatment of hyperinsulinemic hypoglycemia. It is usually given 2–3 times daily, depending on the patient's age, body weight and clinical condition. The dosage is adjusted according to blood glucose levels and therapeutic response. It should be taken consistently as prescribed, with regular monitoring of blood glucose, fluid retention and blood pressure.
DOSAGE AND STRENGTH
Diazoxide is available in oral capsule strengths of 50 mg and 100 mg and as an oral suspension containing 50 mg/mL. The usual starting dose for adults and children with hyperinsulinemic hypoglycemia is approximately 3 mg/kg/day, with a typical dosage range of 3–8 mg/kg/day. In infants and newborns, the usual dosage range is 8–15 mg/kg/day, divided into 2–3 doses. The dosage is adjusted according to blood glucose levels, patient response and tolerance. Regular monitoring is necessary to ensure safety and therapeutic effectiveness.
DRUG INTERACTIONS
Diazoxide may interact with several medications, affecting its therapeutic effects and safety. It can enhance the blood glucose-raising effects of corticosteroids and reduce the effectiveness of insulin and oral antidiabetic drugs. When used with antihypertensive medications or diuretics, it may increase the risk of hypotension and fluid or electrolyte disturbances. Concomitant use with anticoagulants such as warfarin may increase anticoagulant effects. Therefore, careful monitoring of blood glucose, blood pressure, fluid balance and coagulation parameters is recommended during treatment.
FOOD INTERACTIONS
Diazoxide can be administered with or without food. Food may affect the rate of absorption but generally does not significantly alter its overall therapeutic effect. Patients should maintain a consistent dietary pattern and monitor blood glucose levels regularly. Alcohol consumption should be avoided or limited, as it may affect blood glucose regulation and increase the risk of dizziness or blood pressure changes.
CONTRAINDICATIONS
Diazoxide is contraindicated in patients with known hypersensitivity to diazoxide or any of its ingredients. It should be avoided in patients with severe heart failure, significant fluid retention and pulmonary hypertension due to the risk of worsening cardiovascular complications. Caution is necessary in patients with impaired kidney function, liver disorders, diabetes mellitus and electrolyte imbalances. Diazoxide should be used during pregnancy and breastfeeding only when clearly indicated and under medical supervision.
SIDE EFFECTS
Fluid retention (edema).
Excessive hair growth (hypertrichosis).
Nausea and vomiting.
Loss of appetite.
Headache and dizziness.
Tachycardia (increased heart rate).
Hyperglycemia (increased blood glucose).
Electrolyte disturbances.
OVER DOSAGE
Diazoxide may cause excessive elevation of blood glucose levels (severe hyperglycemia), hypotension, fluid retention and electrolyte disturbances. In severe cases, it may lead to cardiovascular complications and impaired consciousness.
TOXICITY
Diazoxide toxicity may occur due to excessive dosage or prolonged administration, resulting in severe hyperglycemia, fluid retention, edema and electrolyte disturbances. It may also cause hypotension, tachycardia, hyperuricemia and impaired renal function. In infants and newborns, serious complications such as pulmonary hypertension and congestive heart failure have been reported. Prolonged exposure may lead to excessive hair growth and abnormalities in blood cell counts. Management involves discontinuation or adjustment of the drug, monitoring of blood glucose and vital signs, and appropriate supportive treatment under medical supervision.
