Amitriptyline versus placebo in post-herpetic neuralgia

$96 AM~TRIPTYLINE VERSUS PLACEBO IN POST-HERPETIC NEURALGIA. I I I Slide C.P.N. Watson, R.J. Evans, K. Reid*, H. Merskey, L. GoldTue 14:30 smith, J. Warsh*. Smythe Pain C l i n i c , Toronto General H o s - Theatre B p i t a l , Ontario, Canada, M5G IL7. -- ............ Aim of I n v e s t i g a t i o n : To determine i f a m i t r i p t y l i n e (AT) is useful in the treatment of post-herpetic neuralgia, and i f so, to see i f i t s action is by i t s antidepressant e f f e c t . Methods: Seventeen patients were randomly assigned to e i t h e r AT or placebo in a double blind cross-over study. The f i r s t medication was taken f o r three weeks with a one week washout period. The second or cross-over medication was taken for a f u r t h e r three weeks. Baseline and weekly evaluations were made of personality (MMPI), pain, depression, side e f f e c t s , other analgesics taken and blood l e v e l s of AT and n o r t r i p t y l i n e (NT). Follow-up was obtained on patients a f t e r the study was completed. Results: We found good to e x c e l l e n t pain r e l i e f in 13 out of 17 patients. (p = .001). We did not find depression in most patients or an antidepressant e f f e c t (p = .22). The median dose of AT was 75 mgs. Median blood level of AT was 65 ngm/ml and NT 30 ngm/ml in responders. No difference was found with poor responders in dosage or blood l e v e l . A "therapeutic window e f f e c t " was noted in three patients. Follow-up demonstrated good responses maintained in 12 out of 17 patients. Conclusions: A m i t r i p t y l i n e was useful in post-herpetic neuralgia and did not act as an antidepressant. Side effects did not l i m i t therapy i f low doses were used. Drug dosage and blood l e v e l s were lower than usual antidepressant doses.

[ ANTIDEPRESSANTS IN POSTHERPETIC NEURALGIA: A DOUBLE-BLIND I 112 Slide STUDY TO INVESTIGATE EFFICACY AND POSSIBLE MODE OF ACTION. I Tue 14:45 G.__W. Hanks * (SPON: R.G. Twycross) Sir Michael Sobell House,[ Theotre ~R Churchill Hospital, Oxford. OX3 7LJ and Oxford Regional Pain Relief Unit, Abingdon Hospital, Abingdon, Oxon. OXI4 IAG. Aim of Investigation: Tricyclic antidepressants are now commonly used in the treatment of patients with post-herpetic neuralgia (PHN) but in those patients who appear to benefit it is not clear which pharmacodynamic effect of the drug has been responsible. This study investigates: (a) the efficacy of amitriptyline and nomifensine, a non-sedative non-tricyclic antidepressant, in patients with PHN; and (b) the relationship of any beneficial effects to antidepressant or sedative activity. Methods: Patients with PHN of at least three months duration are randomly assigned to treatment with amitriptyline 25 mg or nomifensine 50 mg daily, or placebo. After 6 days dosage is doubled and given in a twice daily regimen if there are no contraindications. Assessments are made after ], 3, 5 and 7 weeks of treatment and include visual analogue scales for pain, mood and alertness completed by the patient; the Beck self-rating Depression Inventory; and an observer's clinical global impression. Psychomotor performance is assessed by means of critical flicker fusion threshold and complex reaction time. The quality of sleep and adverse effects are monitored throughout the 7 week period and patients keep a diary card of analgesic consumption. Results: ]5 patients have so far completed the study which continues. The results for these patients and a further cohort will be presented.