Newer Agents

VIII. Newer Agents

1. Zaleplon (Zaplon, Zaso)

Properties and uses: Zaleplone is a nonbenzodiazepine pyrazolo pyrimidine derivative of a short-acting sedative and hypnotic. It acts as a selective agonist at the benzodiazepine α1 receptor subunit on the GABAA receptor complex in the brain. Subunit modulation of the GABA-BZD receptor is hypothesized to be responsible for its hypnotic properties.

Synthesis

Dose: For insomnia—Adult: 10 mg before bedtime. Maximum: 20 mg daily. Elder less than 65 year: 5 mg before bedtime. Maximum 10 mg daily.

2. Zopiclone (Ziclone, Zopicon, Zonap)

Synthesis

Properties and uses: It is a white or slightly yellowish powder, insoluble in water, freely soluble in methylene chloride, sparingly soluble in acetone, insoluble in alcohol. It dissolves in dilute mineral acids. It is a new hypnotic agent structurally unrelated to barbiturates and benzodiazepines. It binds to the GABAA benzodiazepine receptor complex.

Assay: Dissolve the sample in a mixture of 10 ml of anhydrous acetic acid and 40 ml of acetic anhydride. Titrate with 0.1 M perchloric acid and determine the endpoint potentiometrically.

Storage: It should be stored in well-closed airtight containers and protected from light.

Dose: For short-term management of insomnia—Adult: 7.5 mg at bedtime. Elderly: Initially, 3.75 mg at bedtime

3. Zolpidem

Properties and uses: It is a white or almost white crystalline powder, hygroscopic in nature, slightly soluble in water, sparingly soluble in methanol, and insoluble in methylene chloride. It is an imidazopyridine agent and is an agonist at the benzodiazepine α1 receptor subunit of the GABAA receptor, used for the management of insomnia. The selective binding at α1 receptors Subunits of GABAA may explain the relative absence of myo-relaxant and anticonvulsant effects as well as the preservation of deep sleep in human.

Synthesis

Assay: Dissolve the sample in a mixture of 20 ml of anhydrous acetic acid and 20 ml of acetic anhydride. 

Titrate with 0.1 M perchloric acid and determine the endpoint potentiometrically. 

Storage: It should be stored in well-closed airtight containers and protected from light.