Posted by ed_uk on December 21, 2004, at 18:14:57
In reply to anyone taken TCA w/amphetamine?, posted by zeugma on December 21, 2004, at 18:08:02
Hi Mr/Ms Zeugma.....
You may be interested in this info from Stockley's Drug Interactions.........
Tricyclic antidepressants + Methylphenidate or Dexamfetamine (Dextroamphetamine)
Methylphenidate can cause a very marked increase in the plasma levels of imipramine resulting in clinical improvement. Toxicity appears not to have been documented but two adolescents experienced severe mood deterioration while taking both drugs. However, a review of 142 patients suggests the absence of a significant interaction. An isolated report describes a blood dyscrasia in a child given both drugs.Clinical evidence
A study in ‘several patients’ demonstrated a dramatic increase in the plasma levels of desipramine and imipramine during concurrent treatment with imipramine and methylphenidate. In one patient on 150 mg imipramine daily it was observed that 20 mg methylphenidate daily increased the plasma levels of the imipramine from 100 to 700 micrograms/l and of desipramine from 200 to 850 micrograms/l over a period of 16 days. 1Similar effects have been described in other reports. 2,3 Study shows elevation of drug levels takes several days to occur, and several days to wear off. 3 A 9-year-old and a 15-year-old exhibited severe behavioural problems until the imipramine and methylphenidate they were taking were stopped. 4 In contrast a retrospective review in 142 children and adolescents taking either desipramine alone, or desipramine with dexamfetamine (dextroamphetamine) or methylphenidate, indicated the absence of a clinically significant interaction between desipramine and either stimulant. Pharmacokinetic parameters were similar in each group. 5 An isolated report describes leucopenia, anaemia, eosinophilia and thrombocytosis in a child of 10 when given imipramine and methylphenidate. 6
Mechanisms
In vitro experiments with human liver slices indicate that methylphenidate inhibits the metabolism of imipramine, resulting in its accumulation, and this is reflected in raised blood levels. 3 The blood dyscrasia may have been due to the rare additive effects of both drugs. 6Importance and management
Information is limited. Some therapeutic improvement is seen because of the very marked rise in the blood levels of the antidepressant due to methylphenidate, but whether this also can lead to tricyclic antidepressant toxicity is uncertain. It does not seem to have been reported, but the possibility should be considered, although there is evidence that the pharmacokinetics of desipramine is not significantly affected by either methylphenidate or dexamfetamine. Information about other tricyclic antidepressants is lacking. It has been suggested that concurrent use in children and adolescents may be undesirable, due to case reports of adverse behavioural effects. 4
poster:ed_uk
thread:432501
URL: http://www.dr-bob.org/babble/20041217/msgs/432579.html