Diamorphine hydrochloride

CLINICAL USE

Opiate analgesic:Control of severe pain Pain relief in myocardial infarction (MI) Acute pulmonary oedema

DOSE IN NORMAL RENAL FUNCTION

Severe pain: Oral/SC/IM: 5–10 mg 4 hourly, increasing dose as necessaryAcute MI, pulmonary oedema: IV: 2.5–5 mg. Elderly patients – reduce dose by half

PHARMACOKINETICS

Molecular weight &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :423.9

%Protein binding &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :35

%Excreted unchanged in urine &nbsp &nbsp : 0.1

Volume of distribution (L/kg) &nbsp &nbsp &nbsp :40–50 litres

half-life – normal/ESRD (hrs)&nbsp &nbsp &nbsp :1.7–5.3 minutes/–

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

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

10 to 20 &nbsp &nbsp : Use small doses, e.g. 2.5 mg SC/IM approx 6 hourly and titrate to response

<10 &nbsp &nbsp &nbsp &nbsp &nbsp : Use small doses, e.g. 2.5 mg SC/IM approx 8 hourly and titrate to response

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp:Not dialysed. Dose as in GFR <10 mL/min

HD &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :Dialysed. Dose as in GFR

<10 &nbsp &nbsp &nbsp &nbsp &nbsp : mL/min

HDF/high flux &nbsp :Dialysed. Dose as in GFR

<10 &nbsp &nbsp &nbsp &nbsp &nbsp : mL/min

CAV/VVHD &nbsp &nbsp &nbsp:Unknown dialysability. Dose as in GFR 10 to 20 mL/min

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugsAnti-arrhythmics: delayed absorption of mexiletineAntidepressants: possible CNS excitation or depression with MAOIs – avoid concomitant use and for 2 weeks after stopping MAOI; possible CNS excitation or depression with moclobemide; increased sedative effects with tricyclicsAntipsychotics: enhanced sedative and hypotensive effectSodium oxybate: enhanced effect of sodium oxybate – avoid concomitant use

ADMINISTRATION

Reconstition

1 mL water for injection or sodium chloride 0.9% (less may be used, e.g. for SC injection use 0.1 mL for 10 mg)

Route

IV, IM, SC, oral

Rate of Administration

IV: 1 mg/minute

Comments

Monitor BP and respiratory rates

OTHER INFORMATION

Increased cerebral sensitivity in renal impairment which can result in excessive sedation and serious respiratory depression necessitating ventilationMore rapid onset and shorter duration of action than morphineExtreme caution with regular dosing – accumulation of active metabolites may occurNaloxone must be readily available for reversal if required

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