Amitriptyline hydrochloride

CLINICAL USE

Tricyclic antidepressant:

Depression, used especially where sedation is required

Neuropathic pain

DOSE IN NORMAL RENAL FUNCTION

10–200 mg daily depending on indication

PHARMACOKINETICS

Molecular weight : 313.9

%Protein binding : 96

%Excreted unchanged in urine : <2

Volume of distribution (L/kg) : 6–36

half-life – normal/ESRD (hrs) : 9–25/Unchanged

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 : Not dialysed. Dose as in normal renal function

HD : Not dialysed. Dose as in normal renal function

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

CAV/VVHD : Not dialysed. Dose as in normal renal function

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugs Alcohol: increased sedative effect

Analgesics: increased risk of CNS toxicity with tramadol; possibly increased risk of side effects with nefopam; possibly increased sedative effects with opioids

Antiarrhythmics: increased risk of ventricular arrhythmias with amiodarone – avoid concomitant use; increased risk of ventricular arrhythmias with drugs that prolong the QT interval; increased risk of arrhythmias with propafenone

Antibacterials: increased risk of ventricular arrhythmias with moxifloxacin – avoid concomitant use; concentration possibly reduced by rifampicin

Anticoagulants: may alter anticoagulant effect of coumarins

Antidepressants: possibly increased serotonergic effects with duloxetine; enhanced CNS excitation and hypertension with MAOIs and moclobemide; concentration possibly increased with SSRIs; concentration reduced by St John’s wort

Anti-epileptics: convulsive threshold lowered; concentration reduced by carbamazepine, primidone, barbiturates and possibly phenytoin

Antimalarials: avoid concomitant use with artemether/lumefantrine Antipsychotics: increased risk of ventricular arrhythmias especially with pimozide; increased antimuscarinic effects with clozapine and phenothiazines; concentration increased by antipsychotics

Antivirals: increased tricyclic side effects with amprenavir; concentration possibly increased with ritonavir Atomoxetine: increased risk of ventricular arrhythmias and possibly convulsions Beta-blockers: increased risk of ventricular arrhythmias with sotalol

Clonidine: tricyclics antagonise hypotensive effect; increased risk of hypertension on clonidine withdrawal

Dopaminergics: avoid use with entacapone; CNS toxicity reported with selegiline and rasagiline

Pentamidine: increased risk of ventricular arrhythmias

Sibutramine: increased risk of CNS toxicity – avoid concomitant use.

Sympathomimetics: increased risk of hypertension and arrhythmias with adrenaline and noradrenaline; metabolism possibly inhibited by methylphenidate

ADMINISTRATION

Reconstition

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Route

Oral

Rate of Administration

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Comments

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OTHER INFORMATION

Introduce treatment gradually in renal impairment due to dizziness and postural hypotension

Withdraw treatment gradually

Anticholinergic side effects: causes urinary retention, drowsiness, dry mouth, blurred vision and constipation

See how to identify renal failure stages according to GFR calculation

See how to diagnose irreversible renal disease

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