Antihistamines toxicity

Reyes-Jacang A, Wenzl JE. Antihistamine toxicity in children. Clin Pediatr (Phila) 1969 8(5) 297-9. 

Antihistamine toxicity in animals is usually mild, causing sedation and ataxia. Treatment consists mainly of basic supportive measures. 

Tripelennamine as antihistamine, 1, 177 biological activity, 4, 911 toxicity, 4, 912 Tripelennamine, p-bromo-as antihistamine, 2, 520 a-Tripiperideine synthesis, 3, 510 Triprolidine... 

There is an increased risk for bone marrow suppression when levamisole or hydroxyurea are administered witii other antineoplastic dni. Use of levamisole witii phenytoin increases die risk of phenytoin toxicity. Pegaspargase may alter drug response of the anticoagulants. When procarbazine is administered with other central nervous system (CNS) depressants, such as alcohol, antidepressants, antihistamines, opiates, or the sedatives, an additive CNS effect may be seen. Procarbazine may potentiate hypoglycemia when administered witii insulin or oral antidiabetic dru . ... 

A number of drugs in addition to atropine and scopolamine have antimuscarinic properties. Tbese include tricyclic antidepressants, phenothiazines, and antihistamines. Physostigmine has been used in the treatment of acute toxicity produced by these compounds. However, physostigmine can produce cardiac arrhythmias and other serious toxic effects of its own, and therefore, it should be considered as an antidote only in life-threatening cases of anticholinergic drug overdose. 

Elevations of TCA levels may occur when combined with CYP2D6 inhibitors or from constitutional factors. About 7% of the Caucasian population in the USA has a CYP2D6 polymorphism that is associated with slow metabolism of TCAs and other 2D6 substrates. Combination of a known CYP2D6 inhibitor and a TCA in a patient who is a slow metabolizer may result in additive effects. Such an interaction has been implicated, though rarely, in cases of TCA toxicity. There may also be additive TCA effects such as anticholinergic or antihistamine effects when combined with other agents that share these properties such as benztropine or diphenhydramine. Similarly, antihypertensive drugs may exacerbate the orthostatic hypotension induced by TCAs. 

---