Chlorcyclizine

IUPAC nomenclature

1-[(4-Chlorophenyl)(phenyl)methyl]-4-methylpiperazine

Classification

• H1-receptor antihistamine
• Piperazine antihistamine

Physiochemical Properties

Mechanism of Action

Antihistamines such as chlorcyclizine acts as pharmacological antagonists of hitamine at the histamine receptor sites. They do not prevent the release of histamine.

There is also hepatic microsomal enzyme-inducing properties of chlorcyclizine which results in shortening of duration of action of some barbiturates as result of enzyme induction.

Structure Activity Relationship

Structure activity of piperizine antihistamines can be summarized as:

• These are the derivatives of ethylene diamines.
• The connecting moiety is CHN group
• Primary structural difference is nature of para aromatic ring substituent
• These are moderately potent.
• Slow onset of action
• Low incidence of drowsiness
• They also exhibit peripheral and central antimuscarinic activity.

Method of synthesis

Alkylation of 1-methylpiperazine with 4-chlorobenzhydrylbromide gives chlorcyclizine. [1]

Medicinal Uses

Chlorcyclizine has:

• Mildly sedative properties
• Antihistaminic properties
• Slight anticholinergic properties
• Antispasmodic properties
• It enhances the action of epinephrine
• Local anesthetic action

Side Effects

Side effects of chlorcyclizine are:

• Sedation
• Dizziness
• Tinnitus
• Lassitude
• Loss of coordination
• Fatigue
• Blurred vision
• Diplopia
• Euphoria
• Nervousness
• Insomnia
• Tremors 

MCQs

Q.1 Mechanism of action of chlorcyclizine drug includes?

a) Release of histamine in prevented

b) Release of histamine is stimulated

c) Antagonistic effects at H1 receptor for histamine

d) Agonist effects H1 receptor for Histamine

Q.2 Therapeutic use of drug Chlorcyclizine is/are?

a) Local anesthetic

b) Sedative

c) Antihistamine

d) All of the above

Q.3 The type of ring present in the structure of chlorcyclizine?

a) Piperazine

b) Pyridine

c) Cyclohexane

d) All of the above

Q.4 Number of chiral carbons present in the structure of Chlorcyclizine?

a) 0

b) 1

c) 2

d) 3

Q.5 Correct sequence for the True/False for the physiochemical properties of the drug Chlorcyclizine can be?

• Molecular weight: 300.8 gm/mol
• Physical appearance: Oil
• Octanol/water partition coefficient: 3.45

a) TTT

b) TFT

c) FFT

d) TFF

Q.6 Correct statements for the IUPAC nomenclatures of the drugs are?

I. Chlorcyclizine: 1-[(4-Chlorophenyl)(phenyl)methyl]-4-methylpiperazine

II. Carbinoxamine: 2-[(4-Chlorophenyl)-pyridin-2-yl-methoxy]-N,N-dimethyl-ethanamine

III. Edrophonium: Ethyl-(3-hydroxyphenyl)-dimethylazanium

IV. Tenoxicam: 4-hydroxy-2-methyl-1,1-dioxo-N-pyridin-2-ylthieno[2,3-e]thiazine-3-carboxamide

a) I, II

b) III, IV

c) IV

d) I, II, III, IV

 Q.7 Match the following drugs with their correct classifications-

 a) i-A, ii-C, iii-D, iv-B

b) i-D, ii-A, iii-C, iv-B

c) i-D, ii-B, iii-A, iv-C

d) i-B, ii-D, iii-A, iv-C

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ANSWERS

1-c

2-d

3-d

4-b

5-a

6-d

7-b

REFERENCES