Betamethasone

CLINICAL USE

Corticosteroid:

Suppression of inflammatory and allergic disorders

Congenital adrenal hyperplasia

DOSE IN NORMAL RENAL FUNCTION

Oral: 0.5–5 mg dailyInjection: 4–20 mg repeated up to 4 times in 24 hours

PHARMACOKINETICS

Molecular weight :392.5

%Protein binding :65

%Excreted unchanged in urine : 5

Volume of distribution (L/kg) :1.4

half-life – normal/ESRD (hrs) :5.5/–

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 : Dose as in normal renal function

10 to 20 : Dose as in normal renal function

<10 : Dose as in normal renal function

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD :Unknown dialysability. Dose as in normal renal function

HD :Unknown dialysability. Dose as in normal renal function

HDF/high flux :Unknown dialysability. Dose as in normal renal function

CAV/VVHD :Unknown dialysability. Dose as in normal renal function

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugs

Antibacterials: metabolism accelerated by rifampicin; metabolism possibly inhibited by erythromycin

Anticoagulants: efficacy of coumarins may be altered

Anti-epileptics: metabolism accelerated by carbamazepine, barbiturates, phenytoin and primidoneAntifungals: increased risk of hypokalaemia with amphotericin – avoid concomitant use; metabolism possibly inhibited by itraconazole and ketoconazoleA

ntivirals: concentration possibly increased by ritonavir

Ciclosporin: rare reports of convulsions in patients on ciclosporin and high-dose corticosteroids

Cytotoxics: increased risk of haematological toxicity with methotrexate

Diuretics: enhanced hypokalaemic effects of acetazolamide, loop diuretics and thiazide diuretics

Vaccines: high-dose corticosteroids can impair immune response to vaccines; avoid concomitant use with live vaccines

ADMINISTRATION

Reconstition

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Route

Orally, IV, IM, topically

Rate of Administration

IV bolus: over half to one minute

Comments

Can be added to glucose 5% or sodium chloride 0.9%

OTHER INFORMATION

750 micrograms betamethasone ≡ 5 mg prednisolone

Even when applied topically, sufficient corticosteroid may be absorbed to give a systemic effec

tEffects of betamethasone on sodium and water retention are less than those of prednisolone and approximately equal to those of dexamethasone

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