Trihexyphenidyl Carbamazepine

In patients with brain-stem reticular-reflex myoclonus, valproic acid and clonazepam are the most useful agents. In hyperreflexia, treatment is directed against the disabling tonic spasms, rather than jerks. Carbamazepine, phenytoin, and clonazepam are useful agents in this respect. Ballistic overflow myoclonus may improve with anticholinergic drugs such as benztropine or trihexyphenidyl. 

Treatment of palatal myoclonus is often unsuccessful, but phenytoin, carbamazepine, clonazepam, trihexyphenidyl, and baclofen have been effective in some patients. Clonazepam is effective in over half of patients with propriospinal myoclonus, but other anticonvulsants are usually not helpful. Segmental spinal myoclonus is often resistant to drug treatment, but diazepam, carbamazepine, tetrabenazine and, particularly, clonazepam are sometimes effective. 

Noninterfering amitriptyline, amphetamine, atropine, benzoylecgonine, benztropine, caffeine, carbamazepine, carisoprodol, chlorpheniramine, chlorpromazine, chlorprothixene, cimetidine, cocaine, codeine, dextromethorphan, diazepam, diphenhydramine, diphenox-ilate, disopyramide, doxepin, dojylamine, emetine, erythromycin, flurazepam, gluteth-imide, hydrocortisone, hydromorphone, hydroxyzine, imipramine, lidocaine, loxapine, meperidine, meprobamate, methadone, methamphetamine, methapyrilene, methaqualone, methocarbamol, methylphenidate, nicotine, nordiazepam, nortriptyline, orphenadrine, papaverine, pentazocine, phenacetin, phencyclidine, phenmetrazine, phenolphthalein, phentermine, phenylpropanolamine, phenytoin, prazepam, procaineimide, procaine, propoxyphene, propranolol, protriptyline, pseudoephediine, pyrilamine, quinine, salicylam-ide, spironolactone, strychnine, terpin hydrate, thioridazine, thiothixene, triamterene, trifluoperazine, triflupromeizine, trihexyphenidyl, trimeprazine, trimethobenzamide, trimethoprim, tripeleimamine... 

Three patients treated with various antipsychotics (fluphenazine, ha-loperidol, trifluoperazine, chlorpromazine) developed Stevens-Johnson syndrome within 8 to 14 days of starting to take carbamazepine. All 3 had erythema multiforme skin lesions and at least two mucous membranes were affected. After treatment, all 3 were restarted on all their previous drugs, except carbamazepine, without problems. Another case of Stevens-Johnson syndrome has been reported in a patient taking carbamazepine, lithium carbonate, haloperidol and trihexyphenidyl. The reasons are not understood. Stevens-Johnson syndrome with carbamazepine alone is rare, and the risk appears to be mostly confined to the first 8 weeks of treatment. It may be more common in patients being treated for conditions other than epilepsy. It is not possible to say whether the concurrent use of antipsychotics increases the risk of its development, but until more is known it would be prudent to monitor the outcome, particularly during the first 2 weeks of combined use. 

Haloperidol. A study in 9 schizophrenics taking haloperidol (average dose 30 mg daily) found a 55% reduction in plasma haloperidol levels (a mean fall from 45.5 to 21.2 nanograms/mL) when they were given carbamazepine for 5 weeks (precise dose not stated). They also took trihexyphenidyl 10 mg daily and oxazepam 30 mg at night as necessary. Carbamazepine serum levels and the control of the disease remained unchanged. 

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