Trihexyphenidyl Chlorpromazine

A 50-year-old woman with schizophrenia had a 1-year history of gradual deterioration of vision in both eyes. For several years she had been taking chlorpromazine 300 mg/day, trifluoperazine 10 mg/day, and trihexyphenidyl 4 mg/day. Slit lamp examination showed fine, discrete, brown refractile deposits on the corneal endothelium in both eyes, and characteristic bilateral stellate cataracts with dense, dust-like brown-yellow granular deposits were noted along the suture lines in the anterior pole of the lens and obscured the visual axis. 

Extracted acetophenazine, benztropine, butaperazine, carphenazine, chlorpromazine, flu-phenazine, haloperidol, imipramine, mesoridazine, nortriptyline, orphenadrine, pipera-cetazine, promazine, promethazine, thioridazine, thiothixene, trifluoperazine, trifluprom-azine, trihexyphenidyl, trimeprazine... 

Simultaneous amitriptyline, amoxapine, benztropine, brompheniramine, chlorpheniramine, chlorpromazine, clomipramine, cyproheptadine, desipramine, dothiepin, doxepin, fluoxetine, haloperidol, imipramine, loxapine, maprotiline, meperidine, mesoridazine, methadone, metoclopramide, mianserin, moclobemide, nomifensine, nordoxepin, norfluox-etine, norpropoxyphene, northiaden, pentobarbital, pheniramine, promethazine, propoxyphene, propranolol, protriptyline, quinidine, quinine, sulforidazine, thioridazine, thiothixene, tranylcypromine, trazodone, trihexyphenidyl, trimipramine, triprolidine... 

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. 

In a double-blind study 3 patients given a phenothiazine and benzatropine for the parkinsonian adverse effects, developed an intermittent toxic confusional state (marked disturbance of short-term memory, impaired attention, disorientation, anxiety, visual and auditory hallucinations) with peripheral antimusearinies signs. Similar reactions occurred in 3 elderly patients given imipramine or desipramine, with trihexyphenidyl, and in another man given chlorpromazine, benzatropine and doxepin. ... 

A study in psychiatric patients given chlorpromazine 300 to 800 mg daily found that when trihexyphenidyl 6 to 10 mg daily was added, the plasma chlorpromazine levels were reduced from a range of 100 to 300 nanograms/niL to less than 30 nanograms/mL. When the trihexyphenidyl was withdrawn the plasma chlorpromazine levels rose again and clinical improvement was seen. " ... 

Other studies confirm that trihexyphenidyl and orphenadiine reduce the plasma levels and effects of chlorpromazine. In contrast to these reports, another found that trihexyphenidyl increased chlorpromazine levels by 41% in 20 young schizophrenics, but no clinical change was seen. The levels dropped again over the first 4 weeks of treatment. Some of the beneficial actions of haloperidol on social avoidance behaviour ate lost during concurrent treatment with benzatropine, but cognitive integrative function is unaffected. 

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