CYCLIZINE Synthesis, SAR, MCQ,Structure,Chemical Properties and Therapeutic Uses

CYCLIZINE Synthesis, SAR, MCQ,Structure,Chemical Properties and Therapeutic Uses


IUPAC nomenclature



  • H1-receptor antihistamine
  • Piperazine antihistamine


Physiochemical Properties

1 Molecular weight 266.4 g/mol
2 Physical appearance White or creamy white crystalline powder
3 Melting point 105.5oC
4 Solubility Soluble in alcohol and chloroform; slightly soluble in water; freely soluble in ether
5 Octanol/water partition coefficient 3
5 Presence of ring Piperazine, phenyl
6 Number of chiral centers Not present


Mechanism of Action

  • Cyclizine blocks the action of histamine on the receptors present at vomiting center (CTZ).
  • Cyclizine also have anti-cholinergic properties, thus, it also blocks muscarinic receptors.


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 benzhydrylbromide gives cyclizine. [1]

Medicinal Uses

Cyclizine is used for treatment of:

  • Nausea
  • Vomiting
  • Dizziness
  • Motion sickness


Side Effects

Side effects of cyclizine are:

  • Difficult in urination
  • Pounding heartbeats
  • Lightheadedness
  • Drowsiness
  • Weakness
  • Loss of coordination
  • Nausea
  • Dry mouth
  • Constipation
  • Blurred vision
  • Difficult breathing
  • Signs of allergic recations
  • Swellings



Q.1 Correct statements from the following related with the physicochemical properties of drug cyclizine are?

I. Molecular weight: 266.4 gm/mol

II. Appearance: White or creamy white crystalline powder

III. Melting Point: 105.5oC

IV. Solubility: Soluble in alcohol

a) I, II, IV

b) I, III, IV

c) II, IV

d) I, II, III, IV

Q.2 Match the following of the drugs with their correct IUPAC names.

i. Cyclizine A. (RS)-6-(Difluoromethoxy)-2-[(3,4-dimethoxypyridin-2-yl)methylsulfinyl]-1H-benzo[d]imidazole
ii. Lansoprazol B. 2-[[3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl]methylsulfinyl]-1H-benzimidazole
iii. Famotidine C. 3-[({2-[(diaminomethylidene)amino]-1,3-thiazol-4-yl}methyl)sulfanyl]-N-sulfamoylpropanimidamide
iv. Pentoprazole D. 1-benzhydryl-4-methyl-piperazine

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

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

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

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

Q.3 Cyclizine has actions on?

I. Vomiting center

II. Cholinergic receptors

III. Muscarinic receptors

IV. Nicotinic receptors

a) I, III

b) I, IV

c) I, II, III

d) I

Q.4 Correct sequence for True/false for the classification of the drug can be?

  • Cyclizine: H1-receptor antihistamine drug
  • Haloperidol: Inhalational anesthetics
  • Codeine: Narcotic analgesic
  • Triclofos sodium: Sedative-hypnotics





Q.5 Piperizine antihistamine drugs are derivatives of?

a) Ethylene diamine

b) Piperidine

c) Benzodiazepine

d) Phenothiazine

Q.6 Type of rings present in the structure of cyclizine?

I. Pyridine

II. Piperazine

III. Phenyl

IV. Benzodiazepine

a) I, IV

b) I

c) II, III

d) II 

Q.7 Side effect of drug Cyclizine is/are?

a) Difficulty urination

b) Loss of coordination

c) Nausea

d) All of the above





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[1] Vardanyan R, Hruby V. Synthesis of essential drugs. Elsevier; 2006 Mar 10.


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