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

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


IUPAC nomenclature

(RS)-1-[(4-chlorophenyl)- phenyl-methyl]-4- [(4-tert-butylphenyl) methyl] piperazine


  • H1-receptor antihistamine
  • Piperazine antihistamine


Physiochemical Properties

1 Molecular weight 433 g/mol
2 Physical appearance Liquid
3 Melting point 218oC
4 Solubility 2.46e-04 g/L
5 Octanol/water partition coefficient 7.1
5 Presence of ring Piperazine, phenyl
6 Number of chiral centers 1


Mechanism of Action

  • Buclizine blocks the action of histamine on the receptors present at vomiting center (CTZ).
  • Buclizine 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

i. 4-chlorobenzhydryl chloride is reacted with ethyl piperazine N-carboxylate to give ethyl-4-(4-chlorobenzhydryl)piperazine-1-carboxylate.

ii. The above formed compound is treated with NaOH to get 1-(4-chlorobenzhydryl)piperazine.

iii. The last is reacted with 4-tert-butyybenzyl chloride to get Buclizine. [1]


Medicinal Uses

Buclizine is used for treatment of:

  • Nausea
  • Vomiting
  • Dizziness
  • Motion sickness


Side Effects

Side effects of Buclizine are:

  • Drowsiness
  • Vomiting
  • Dry mouth
  • Fatigue
  • Headache
  • Difficulty in breathing
  • Swelling of face



Q.1 What can be the correct IUPAC nomenclature of Buclizine?

a) (RS)-1-[(4-chlorophenyl)- phenyl-methyl]-4- [(4-tert-butylphenyl) methyl] pyrimidine

b) (R)-(+)-2-([3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl]methylsulfinyl)-1H-benzo[d]imidazole

c) (RS)-1-[(4-chlorophenyl)- phenyl-methyl]-4- [(4-tert-butylphenyl) methyl] piperazine

d) (R)-(+)-2-([3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl]methylsulfinyl)-imidazole

Q.2 Which amongst the following statements is/are incorrect related to the SAR of Piperazine antihistamines?

I. These are the derivatives of Ehanol.

II. The connecting moiety is CHN group

III. Primary structural difference is nature of para aromatic ring substituent

a) I

b) II, III

c) I, III

d) I, II, III

Q.3 Types of rings present in the structure of Buclizine?

I. Piperazine

II. Pyridine

III. Pyrolle

IV. Phenyl

a) I, III

b) I, IV

c) II, IV

d) II, III

Q.4 Side effects of drug Buclizine is/are?

a) Drowsiness

b) Vomitting

c) Headache

d) All of the above

Q.5 Match the following drugs with their correct molecular weight-

i. Buclizine A. 426.6 gm/mol
ii. Hydroxyzine B. 266.4gm/mol
iii. Oxatomide C. 433 gm/mol
iv. Cyclizine D. 374.9 gm/mol

 a) i-A, ii-B, iii-C, iv-D

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

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

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

Q.6 An example of drug from class piperazine antihistamine drug?

a) Buclizine

b) Cimetidine

c) Glycopyrrolate

d) All of the above 

Q.7 Octanol/water partition coefficient of Buclizine is?

a) 2.5

b) 3.2

c) 4.8

d) 7.1





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[1] DE 964 048 (H. Morren; appl. 1952; B-prior. 1951).


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