Trimeprazine (Temaril)

Introduction

Trimeprazine, a member of the phenothiazine class, stands as a notable antihistamine celebrated for its dual action—antagonism at H1 histamine receptors, and sedative properties. Widely employed for the relief of allergic symptoms, including itching, sneezing, and runny nose, trimeprazine also finds utility as a preoperative sedative.

Structure

Synthesis

Mechanism of action

Trimeprazine exerts its therapeutic effects through a dual mechanism of action:

1. Antagonism at H1 Histamine Receptors:
   • Trimeprazine acts as an antagonist at H1 histamine receptors.
   • By blocking histamine effects, it alleviates symptoms associated with allergic reactions, including itching, sneezing, and a runny nose.
2. Antimuscarinic (Anticholinergic) Activity:
   • Trimeprazine possesses antimuscarinic properties.
   • This contributes to its sedative effects and may help manage conditions where calming or sedation is desired.

Properties and uses: 

It is a white crystalline powder, soluble in water. Primarily used to relieve symptoms associated with allergies, such as itching, sneezing, and runny nose.

Dose:

 The usual dose for adults is 10–40 mg per day orally.