Increasing attention to biochemical research in depression, many studies were done on 3-methoxy-4-hydroxy phenylglycol (MHPG), a metabolite of norepinephrine. The results were howerer controversial; some reported increased urinary MHPG excretion and others decreased urinary MHPG excretion in depression. On the other hand, many researchers have tried to find out possible different therapeutic effect of tricyclic antidepressants according to urinary MHPG level. Some studies suggested better antidepressant effect of imipramine in patients with decreased urinary MHPG and that of amitriptyline in patients with increased urinary MHPG. Mean-while others reported that urinary MHPG Ievel failed in predicting antidepressant effect of several tricyclics.
The authors tried to evaluate therapeuticeffect of the two tricyclic antidepressants, imipramine and amitriptyline and its relation to urinary MHPG level, for the purpose of looking into the feasibility of using urinary MHPG level as a guide in choosing a more effective antidepressant.
Fourty four endogenous depression were the initial research subject. But 17 were discarded; 15 were early discharged, 2 had con-current hypothyroidism. Among final 27 subjects, 20 were unipolar endogenous depression and 7 bipolar depression, and 10 males and 17 females. As a control group, 20 healthy males were studied on urinary MHPG.
Urine samples were collected and severities of depression were assessed by Hamilton´s Rating Scale for Depression on the first, 7th, 14th and 21st days of admission. MHPG was determined by gas-liquid chromatography. Selection of antidepressant, impramine or amitriptyline was therapists´ free choice.
The findings are as follows:
1. Urinary MHPG excretion was lower in the patient group compared to the control.
2. Patients with endogenous depression could be devided into three groups according to the urine MHPG level; high, medium and low-MHPG groups.
3. In the high MHPG-group, imipramine had better therapeutic effect. In the medium M HPG group, there was no difference in therapeutic effect of respective antidepressants. In the low MHPG group, amitriptyline appears to have better antidepressant effect.
4. As patients improved with antidepressant medication, urinary MHPG excretion was increased.
The data we have presented suggest abnormal norepinephrine metabolism in the endogenous depression and imipramine had better therapeutic effect in the high MHPG group, amitriptyline appears to have better antidepressant effect in the low MHPG group. It also challenges the view that therapeutic effect of imipramine and amitriptyline is mediated simply by activating noradrenergic system.
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