| Serotonin (5-HT) plays a crucial role in mediating the descending
pain inhibitory systems and in the pathophysiology of migraine.
Previous studies regarding the use of 5-Hydroxytryptophan (5-HTP),
the active precursor of 5-HT, in the treatment of Chronic Primary
Headache (CPH) have been inconclusive so far. In order to assess the
efficacy of the serotonin active precursor in chronic headache
prophylaxis, a double-blind cross-over study has been carried out in
31 patients with CPH, comparing L-5-HTP to placebo. Clinical
syndromes included: (a) migraine (16 patients); (b) mixed headache (6
patients); (c) psychogenic headache (5 patients); (d) muscle
contraction headache (4 patients). L-5-HTP was administered for two
months at daily doses of 400 mg p.o. The reduction in severity and
frequency of headache in patients taking the active drug and placebo
was noted. Mood patterns were also taken into consideration. L-5-HTP
proved to be more effective than placebo in reducing both headache
frequency and severity, but the difference was not statistically
significant. Favourable responses (greater than 50% average reduction
in headache symptoms) were obtained in 48% of the cases after the
second month of treatment. No significant difference in therapeutic
response was observed as related to different clinical syndromes,
except for psychogenic headache patients, who responded poorly to the
active drug. Side effects, experienced in 19% of the cases, were
generally mild and transient. We conclude that L-5-HTP is a
medication of moderate efficacy and remarkable safety, providing us
with another alternative approach to CPH prophylaxis.
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