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Unit Code 500516:
Desipramine, Serum

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Useful For

Monitoring desipramine therapy

Clinical Information

Desipramine (Norpramin) is a tricyclic antidepressant; it also is a

metabolite of imipramine. These drugs have also been employed

in the treatment of enuresis in childhood and severe obsessive-

compulsive neurosis. Desipramine is the antidepressant of choice

in patients where maximal stimulation is indicated.

 

Desipramine exhibits 92% bioavailability and is approximately

90% protein bound. As with the other antidepressants, it undergoes

hepatic metabolism and renal elimination with a clearance rate of

30 mL/min/kg. The volume of distribution is 34 L/kg, and the elimination

half-life is 15 hours to 20 hours.

 

The therapeutic concentration of desipramine is 75 ng/mL to 275 ng/mL.

About 1 to 3 weeks of treatment are required before therapeutic

effectiveness becomes apparent.

 

The most frequent untoward reactions are those attributable to

anticholinergic effects: dry mouth, constipation, dizziness, tachycardia,

palpitations, blurred vision, and urinary retention. These side effects

occur at blood concentrations in excess of 300 ng/mL, although

they may occur at therapeutic concentrations in the early stage of

therapy. Cardiac toxicity (first-degree heart block) is usually associated

with blood concentrations >500 ng/mL.

 

Concurrent administration of phenothiazines (perphenazine displays

the strongest effect) will cause accumulation of the metabolite as the

conversion of desipramine to 10-hydroxydesipramine is blocked.

Dosage adjustments may be in order in this situation. Desipramine

is metabolized by the cytochrome P450 system; all drugs that activate

the P450 system (ie, phenobarbital) will increase the rate of clearance

of desipramine.

Reference Values

Therapeutic concentration:  75-225 ng/mL

Toxic concentration:  > or =500 ng/mL

Interpretation

Desipramine is administered in doses of 100 mg/day to 200 mg/day

to yield therapeutic levels of 75 ng/mL to 225 ng/mL.

Cautions

Specimens that are obtained from serum gel tubes are not acceptable.

Clinical Reference

Ziegler VE, Biggs JT, Rosen SH, et al:  Imipramine and desipramine

plasma levels: relationship to dosage schedule and sampling time.

J Clin Psychol 1978;39:660-663

Key