Dexamethasone

CLINICAL USE

Corticosteroid:Cerebral oedema Suppression of inflammatory and allergic disordersRheumatic disease Congenital adrenal hyperplasia Anti-emetic (unlicensed indication)

DOSE IN NORMAL RENAL FUNCTION

Cerebral oedema: 10 mg IV followed by 4 mg IM every 6 hoursRheumatic disease: intra-articular, intrasynovial: 0.4–4 mg —(as dexamethasone phosphate)soft tissue infiltration: 2–6 mg —Oral: 0.5–10 mg daily, IV/IM: 0.5–24 mg

PHARMACOKINETICS

Molecular weight &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :392.5 (472.4 as phosphate)

%Protein binding &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :77

%Excreted unchanged in urine &nbsp &nbsp : 65

Volume of distribution (L/kg) &nbsp &nbsp &nbsp :0.8–1

half-life – normal/ESRD (hrs)&nbsp &nbsp &nbsp :3.5–4.5/–

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 &nbsp &nbsp : Dose as in normal renal function

10 to 20 &nbsp &nbsp : Dose as in normal renal function

<10 &nbsp &nbsp &nbsp &nbsp &nbsp : Dose as in normal renal function

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp:Not dialysed. Dose as in normal renal function

HD &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :Not dialysed. Dose as in normal renal function

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

CAV/VVHD &nbsp &nbsp &nbsp:Removal unlikely. Dose as in normal renal function

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugsAntibacterials: metabolism accelerated by rifampicin; metabolism possibly inhibited by erythromycinAnticoagulants: efficacy of coumarins may be alteredAnti-epileptics: metabolism accelerated by carbamazepine, barbiturates, phenytoin and primidoneAntifungals: increased risk of hypokalaemia with amphotericin – avoid concomitant use; metabolism possibly inhibited by itraconazole and ketoconazole; caspofungin concentration possibly reduced (may need to increase dose). Antivirals: concentration of indinavir, lopinavir and saquinavir possibly reduced; concentration possibly increased by ritonavirCiclosporin: rare reports of convulsions in patients on ciclosporin and high-dose corticosteroidsCytotoxics: increased risk of haematological toxicity with methotrexateDiuretics: enhanced hypokalaemic effects of acetazolamide, loop diuretics and thiazide diureticsVaccines: high dose corticosteroids can impair immune response to vaccines; avoid concomitant use with live vaccines

ADMINISTRATION

Reconstition

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Route

Oral, IV, IM, intra-articular, intrasynovial

Rate of Administration

IV slowly over not less than 5 minutes. If underlying cardiac pathology, infusion over 20–30 minutes advised

Comments

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OTHER INFORMATION

Dexamethasone sodium phosphate 1.3 mg = dexamethasone 1 mg750 mcg of dexamethasone is equivalent to 5 mg prednisolone Injection solution can be administered orally or via naso-gastric tubeTablets will disperse in water

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