27
Diphenhydramine
Benadryl
Trihexyphenidyl hydrochloride
Artane
Acute dystonia, parkinsonism Acute dystonia, parkinsonism
Histamine H1 antagonist Muscarinic antagonist
Capsule: 25, 50
Oral elixir: 12.5/5 mL
Oral solution: 12.5/5 mL, 6.25/1 mL
Tablet: 25, 50
Solution, injection: 50/1 mL
Other brand name formulations are
available for allergy relief
Oral elixir: 0.4/mL (473 mL)
Tablet: 2, 5
Oral: 75–200
Solution, injection: 10–50
Oral: 5–15
40%–70% 100%
1–4 1.3
76%–85% Not known
Hepatic Not known
Extensively hepatic N-demethylation
via CYP2D6; minor demethylation
via CYP1A2, CYP2C9 and CYP2C19;
inhibits CYP2D6 (weak)
None known
Inactive Not known
4–8 4
Urine (as metabolites and unchanged
drug)
Urine and bile
No dose adjustments noted in
labeling
No dose adjustments noted in
labeling
