Clinical and biochemical effects during
treatment of depression with
nortriptyline: The role of
1 0 - hydroxynortriptyline
Plasma concentrations of nortriptyline (NT) and its major metabolite 10-hydroxy-NT (10-0H-NT) were
measured in 30 patients with depression, treated with NT for 3 weeks. Nine patients who recovered
completely had plasma concentrations of NT and 10-0H-NT ranging from 358 to 728 nmol/L and from
428 to 688 nmol/L, respectively. Of the 21 patients who did not recover completely, only four had plasma
concentrations within the window limited by these two plasma concentration ranges. A correlation was
found between the degree of amelioration and the plasma concentration of NT (r, = 0.469; P < 0.01).
Lumbar punctures were performed in 26 patients before and after 3 weeks of NT treatment. Dur-
ing treatment there was a 30.9% mean decrease in the noradrenaline metabolite 4-hydroxy-3-me-
thoxyphenylglycol (HIVIPG) in cerebrospinal fluid (CSF). We could not evaluate the extent to which this
decrease was caused by NT or 10-0H-NT, respectively, because both are strong inhibitors of noradrenaline
uptake. The ratio between the concentration of NT and 10-0H-NT in CSF correlated to the reduction
of HA/PG in CSF (r = 0.397; P < 0.05) and to the amelioration of depression (r, = 0.623; P < 0.001).
This might indicate that NT and 10-0H-NT interact on the noradrenaline system in a nonadditive way.
During treatment there was a 15.2% decrease in CSF concentration of the serotonin metabolite
5-hydroxyindoleacetic acid. The reduction was significantly correlated to the CSF concentration of NT
but not to that of 10-0H-NT. This is in accordance with the fact that NT is a more potent inhibitor of
serotonin uptake than is 10-0H-NT. The dopamine metabolite homovanillic acid in CSF decreased
significantly by 10.0%. The biochemical data indicate that noradrenergic, serotoninergic, and dopamin-
ergic systems are affected by NT treatment and that 10-0H-NT might be more selective on noradrenergic
neurons than the parent drug. (CLIN PHARMACOL THER 1987;42:10-9.)
Conny Nordin, M.D., Leif Bertilsson, Ph.D., and Bo Siwers, M.D. Huddinge, Sweden
Interpretation of the plasma concentration-effect re-
lationship of a drug is complicated by the occurrence
of active metabolites.' The major metabolite of nor-
triptyline (NT), 10-hydroxy-NT (10-OH-NT) inhibits
From the Departments of Psychiatry and Clinical Pharmacology at
the Karolinska Institute, Huddinge University Hospital.
Supported by grants from the Swedish Medical Research Council
(Nos. 3902 and 5454), the Karolinska Institute, and the Soder-
Received for publication Sept. 19, 1986; accepted Dec. 26, 1986.
Reprint requests: Dr. C. Nordin, Department of Psychiatry, Huddinge
Hospital, S-141 86 Huddinge, Sweden.
noradrenaline (NA) uptake with a potency about 50%
that of NT.2 Because 10-0H-NT concentrations in
plasma and cerebrospinal fluid (CSF) usually are higher
than those of the parent drug,' 10-0H-NT probably
contributes to the effects of NT on the noradrenergic
system and may thereby influence NT's antidepressant
Treatment of depression with an NA uptake in-
hibitor like NT decreases the CSF concentration of
the NA metabolite 4-hydroxy-3-methoxyphenyl glycol
(HMPG), probably as a result of feedback inhibition of
transmitter biosynthesis .4 Analogously, treatment with
inhibitors of serotonin uptake such as chlorimipramine
Table I. Data on patients
and zimeldine results in a decreased level of the sero-
tonin metabolite 5-hydroxyindoleacetic acid (5-HIAA)
in CSF.' NT also slightly decreases 5-HIAA in CSF,
suggesting that it inhibits serotonin uptake.' A recent
study' shows that treatment with NT inhibits serotonin
uptake by platelets and that this effect is much stronger
for NT than for 10-0H-NT.
It has been hypothesized that CSF concentrations of
5-HIAA7" of the dopamine metabolite homovanillic
acid (HVA)12'13 and of HMPG-14 may predict the outcome
of treatment with various antidepressant drugs. Thus
endogenously depressed patients with high CSF con-
centrations of 5-HIAA (>15 ng/ml) have been reported
to respond better to NT than do patients with a lower
(<15 ng/ml) concentration.' However, relationships are
difficult to evaluate because of the many factors influ-
encing CSF concentrations of transmitter metabolites. '5
We have now examined indirectly the clinical and
biochemical roles of 10-0H-NT during treatment of
depression with NT.
The study included 39 nondelusional, depressed in-
patients who came to our psychiatric clinic on their own
initiative and who fulfilled the Feighner criteria for pri-
mary depression.' The subjects had a median depres-
sion score of 17, which reflects a depression of mod-
erate severity (see Methods) (Table I). All were judged
by two experienced psychiatrists to require inpatient
care. All were physically healthy according to history,
routine laboratory tests, and physical examination.
None of the patients had received treatment with an-
tidepressants or neuroleptics for 1 month before inclu-
sion. Some patients had been given occasional doses
of benzodiazepines during this period.
During an initial placebo period five patients were
excluded because of spontaneous recovery. Four pa-
tients left the study during the first week of NT treat-
ment. Of these, two recovered, one discontinued med-
ication because of a severe orthostatic reaction, and one
was excluded after a reconsideration of the Feighner
criteria. Data on the subjects are given in Table I. Of
the 30 patients with depression who completed 3 weeks
of treatment, 27 had unipolar disorder, two had bipolar
disorder with histories of manic episodes, and one had
bipolar disorder with previous hypomanic episodes.
After a placebo period of 3 to 7 days, NT (Sensaval,
Pharmacia Laboratories) treatment was begun at 50 mg
t.i.d. (8 AM, 2 PM, and 10 Pm) in 31 patients, 50 mg
b.i.d. (8 AM and 10 Pm) and 25 + 50 mg (8 AM and
10 Pm) in two patients with histories of side effects,
and 25 mg b.i.d. (8 AM and 10 Pm) in a 75-year-old
patient. These doses were maintained for at least 3
weeks except for the four patients excluded who were
treated with 50 mg t.i.d. Occasional daily doses of
nitrazepam (5 mg) or oxazepam (15 to 30 mg) were
Plasma samples were drawn at 8 AM, before the
morning dose of NT, once or twice a week from the
second week of treatment. Blood was collected in hep-
arinized glass tubes and centrifuged within 30 minutes.
Plasma was separated and stored at
ysis. All samples from each patient were analyzed si-
multaneously by mass fragmentography.19-" The re-
ported values of NT and unconjugated 10-0H-NT (sum
of E and Z isomers) are the means of the concentrations
measured during the second and the third weeks of
Lumbar punctures were performed by a standardized
technique at the level L 4-L 5 before and after 3 weeks
of NT treatment. Twelve milliliters of CSF was col-
lected in the early morning with the patient in a sitting
position after at least 8 hours of fasting and strict bed
rest. CSF samples were centrifuged immediately,
frozen in 3 ml aliquots in silanized glass tubes, and
stored at 20° C until analysis. CSF samples from
each patient were analyzed simultaneously. Concentra-
tions of NT, unconjugated 10-OH-NT (sum of E and Z
20° C until anal-
(mean ± SD)
46 ± 8
43 ± 13
45 ± 8
44 ± 13
45 ± 8
44 ±- 12
After the placebo period
After 3 weeks of NT treatment
Depression and 10-hydroxynortriptyline
12 Nordin et al.
Placebo Weeks of NT treatment
Fig. 1. Median depression scores in patients with low (<15 ng/m1 CSF) (n = 10) and high (>15
ng/ml CSF) (n = 19) concentration of 5-HIAA before treatment (x, difference between the two
groups at the end of placebo period [P < 0.05]; xx, difference between depression scores after 3
weeks of NT treatment compared with after placebo period; this was significant in both groups
[P < 0.01]).
<1 5ng 5-HIAA/m1 CSF
>1 5ng 5-HIAA/m1 CSF
(n=1 9 1xx
isomers), and amine metabolites 5-HIAA, HVA, and
HMPG were analyzed by mass fragmentography.17,19,20
At three lumbar punctures only 6 ml CSF was obtained.
The concentrations of 5-HIAA and HVA in these 6 ml
samples were adjusted to correspond to a 12 ml sample
of CSF according to Bertilsson et al.'
Severity of depression was assessed by using 10 items
described in the Montgomery-Asberg Depression Rat-
ing Scale (MADRS)2' at the time of inclusion, at the
end of the placebo period, and then once a week. Scale
steps 0, 1, 2, and 3 with half steps were used. The sum
of the rating scores was used as a measure of severity.
These scores are half of the corresponding MADRS
scores. The amelioration score was defined as the dif-
ference between the score at baseline (week 0) and
during treatment (week 3). Most ratings were performed
by two of the authors in a joint interview. The ratings
of C. N. were used in the statistical analysis except for
some interviews when B. S. rated the patient alone.
The added scores were used to calculate the Spearman
rank correlation coefficient. The interrater reliability
was 0.92 (n = 25) at inclusion and 0.95 (n = 17) after
3 weeks of NT treatment.
Side effects were rated simultaneously with depres-
sion with a specially designed scale as described by
Asberg et al 22 The summed score of the 11 items was
used as the "raw side effect score." By subtracting the
pretreatment raw side effect score from that after 3
weeks of treatment, the "corrected side effect score"
was obtained. Raw and corrected scores after 3 weeks
of treatment were used in the statistical analysis.
CLIN PHARMACOL THER
All statistical analyses were performed with programs
from the MIMER/ST system on a computer at the Ka-
Rating data were analyzed by nonparametric statistics
according to Siegel." Parametric statistics were used
according to Snedecor and Cochran.'
The study was approved by the Ethics Committee at
the Huddinge Hospital.
Clinical effects. Thirty patients completed 3 weeks
of NT treatment. Lumbar puncture was performed twice
(before and after 3 weeks of treatment) in 26 patients
and once (before treatment) in three patients.
The 10 patients with a low pretreatment concentration
of 5-HIAA (<15 ng/ml CSF) tended to have higher
depression scores than the 19 patients with a high con-
centration (>15 ng/ml CSF) from the time of inclusion
until week 3 (significant only at week 0; Mann-Whitney
U test, U = 51.5; P < 0.05) (Fig. 1). In both groups
of patients there was a highly significant reduction of
median depression score after 3 weeks of treatment
(Wilcoxon matched-pairs signed-ranks test; T = 0.00
and T = 6.50, respectively; P < 0.01) (Fig. 1).
The steady-state NT concentrations ranged from 186
to 960 nmol/L in plasma and from 13 to 98 nmol/L in
CSF. For 10-0H-NT the corresponding ranges were 313
to 1072 nmol/L and 24 to 131 nmol/L.
In the total group of patients there was a correla-
tion between the amelioration score and the plasma
(n = 30; I., = 0.469; P < 0.01), as well as CSF
*P <0.01; TP < 0.05
P < 0.001.
(n = 25; r, = 0.515; P < 0.01) concentration of NT
(Fig. 2; Table II). In patients with a high 5-HIAA
concentration, a correlation was found between ame-
lioration score and the plasma NT (n = 19; rs =
0.594; P < 0.05), as well as CSF NT (n = 17;
r, = 0.561;P <0.05). In patients with a low 5-HIAA
concentration, the relationships between amelioration
score and the plasma NT (n = 10; r, = 0.304), as well
as CSF NT (n = 8; r, = 0.448), were positive but did
not reach statistical significance.
Rank correlations were also calculated for relation-
ships between amelioration score and the plasma and
CSF concentration:NT (nM)
Fig. 2. Relationships between amelioration score and NT concentrations in plasma (left) and CSF
(right) in patients with a low (0) (<15 ng/ml CSF) and a high () (>15 ng/ml CSF) pretreatment
5-HIAA concentration. (In one patient () no CSF was obtained.) Coefficients of Spearman rank
correlation are given in Table II.
Table II. Relationships between amelioration score and concentrations of NT and 10-0H-NT in plasma
CSF concentrations of (a) 10-0H-NT, (b) NT +
(10-0H-NT), and (c) NT + 0.57 (10-0H-NT). (The
factor 0.57 is derived from in vitro data2; Table II.) No
correlation was stronger than that with NT alone.
Correlations were also found between the amelio-
ration score and the ratio NT/10-0H-NT in plasma
(n = 30; r, = 0.420; P < 0.05) and CSF (n = 25;
r, = 0.623; P < 0.001) (Table II). In patients with a
high CSF 5-HIAA concentration, corresponding cor-
relations were found for plasma (n = 19; rs = 0.415;
P < 0.05) and CSF (n = 17; r, = 0.636; P <0.01).
In patients with a low CSF 5-HIAA, a correlation
Pretreatment level of 5-HIAA in CSF
NT + 10-OH-NT
NT + 0.57 (10-OH-NT)
Plasma concentration:NT (nM)
Depression and 10-hydroxynortriptyline 13
14 Nordin et al.
*P < 0.01; tP < 0.05.
was found for CSF (n = 8; r, = 0.673; P < 0.05) but
not for plasma (n = 10; r, = 0.403; P not signif-
Before starting further statistical analysis, the pa-
tients were grouped as follows according to the final
depression score at week 3: responders:
partial responders: 5.5 to 10 (n = 9); and nonrespond-
ers: >10 (n = 12).
The nine responders had steady-state plasma NT con-
centrations within a range of 358 to 728 nmol/L with
a simultaneous plasma 10-0H-NT range of 428 to 688
nmol/L. In CSF the corresponding ranges were 23 to
60 nmol/L for NT and 47 to 81 nmol/L for 10-0H-NT
(Fig. 3). Only four patients who had partial or no
5 (n = 9);
Table IV. Coefficients of correlation between
pretreatment CSF concentrations of amine
metabolites and body height and age (n = 26)
CLIN PHARMACOL THER
response had plasma or CSF concentrations within the
windows limited by these two concentration ranges
No correlation was found between the plasma and
CSF concentrations of NT and 10-0H-NT and the raw
or corrected side effect score nor any specific side
Biochemical effects. As expected from a strong in-
hibitor of NA uptake, CSF concentrations of HMPG
decreased significantly (30.9%; P < 0.001) during
NT treatment (Table III). Concentrations of 5-HIAA
(P < 0.001) and HVA (P < 0.05) also decreased but
less markedly (Table III).
The pretreatment CSF concentrations of 5-HIAA and
HVA were correlated to body height (Table IV), and
CSF HMPG concentration was correlated to age (Table
IV). A correlation was found between the concentra-
tions of 5-HIAA and HVA before treatment (Table V).
There was also a significant, but weaker, correlation
between the CSF 5-HIAA and HMPG (Table V). For
all three amine metabolites, CSF concentrations before
and during NT treatment were strongly correlated
We studied the effects of NT and 10-0H-NT during
94.1 ± 37.7
200.4 -± 108.2
49.4 ± 10.3
Plasma concentration:NT (nM)
CSF concentration:NT (nM)
Fig. 3. Relationships between the concentrations of NT and 10-0H-NT in plasma (left) (n = 30)
and CSF (right) (n = 23) in patients grouped according to depression score after 3 weeks of NT
E , 5.5 to 10; and , >10).
Table III. Amine metabolite levels in CSF of 26 patients before and during NT treatment (mean ± SD)
(mean -± SD)
78.5 ± 33.0
176.2 ± 108.2
33.7 ± 6.0
-15.2 ± 20.2
-10.0 ± 23.2
-30.9 ± 10.3