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

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


IUPAC nomenclature



  • H1-receptor antihistamine
  • Piperidine derivative antihistamine drug


Physiochemical Properties

1 Molecular weight 287.4 g/mol
2 Physical appearance Crystals from dilute ethanol
3 Melting point 112.8oC
4 Solubility Soluble
5 Octanol/water partition coefficient 4.69
5 Presence of ring Piperidine ring
6 Number of chiral centers Not present


Mechanism of Action

  • Cyproheptadine antagonizes the effect of histamine HA-receptors by competing with free histamine for binding at HA-receptor sites. This helps in reducing the negative symptoms occurring due to HA-receptor binding.
  • The drug also competes with serotonin at receptor sites in smooth muscles of intestine and at other locations.
  • Cyproheptadine also stimulates the appetite by antagonistic effects of serotonin on the appetite center of the hypothalamus.


Structure Activity Relationship

General structure activity of first generation H1-receptors antagonist can be summarized as:

  • Ethylene chain gives maximum activity.
  • Increasing or decreasing the chain length decreases the activity of drug, but promethazine is an exception.
  • Chain may be present in saturated or unsaturated form, or sometimes a part of a ring system.
  • Diaryl substitution is essential for significant H1 receptor affinity.
  • Terminal nitrogen atom should be tertiary in nature.


Method of synthesis

i. Reaction of 1-methyl-4-magnesiumchloropiperidine with 5H-dibeno[a,d]cyclohepten-5-one to form a carbinol.

ii. The formed carbinol is dehydrated under acidic condition to give cyproheptadine. [1]

Medicinal Uses

Cyproheptadine is used for treatment of:

  • Allergic symptoms
  • Sneezing
  • Itching
  • Bronchial asthma attacks


Side Effects

Side effects of cyproheptadine are:

  • Dizziness
  • Drowsiness
  • Constipation
  • Blurred vision
  • Dry mouth
  • Trouble swallowing
  • Seizures
  • Allergic reactions




Q.1 Match the following with correct SAR of the first generation H1 receptor antihistamine drugs:

i. Terminal nitrogen atom should be A. Secondary in nature
ii. Ethylene chain gives B. Tertiary in nature
  C. Minimum activity
  D. Maximum activity

 a) i-A, ii-C

b) i-A, ii-D

c) i-B, ii-C

d) i-B, ii-D

Q.2 Correct sequence for the True/False for correct IUPAC names of the drug can be?

  • Cyproheptadine: 4-(5H-Dibenzo[a,d]cyclohepten-5-ylidene)-1-methylpiperidine
  • Lomustine: 2-(diphenylmethoxy)-N,N-dimethylethanamine
  • Lorcainide: (2R)-2-{2-[(1R)-1-(4-chlorophenyl)-1-phenylethoxy]ethyl}-1-methylpyrrolidine
  • Felodipine: 4-hydroxy-2-methyl-N-(5-methyl-1,3-thiazol-2-yl)-1,1-dioxo-1λ6,2-benzothiazine-3-carboxamide





Q.3 Molecular weight of Cyproheptadine is?

a) 245.3 gm/mol

b) 452.0 gm/mol

c) 287.4 gm/mol

d) 46.9 gm/mol

Q.4 Along with antihistaminic property, Cyproheptadine also has?

a) Anti-metabolic activity

b) Anti-neoplastic actvity

c) Anti-serotonergic activity

d) Anti-hyperlipidemic activity

Q.5 Which amongst the following is not a therapeutic use of drug Cyproheptadine?

a) Chronic urticaria

b) Bronchial asthma attacks

c) Itching

d) Anesthetics

Q.6 Which of the following drug and their classification are correct?

I. Cyproheptadine: Proton pump inhibitor

II. Cocaine: Local anesthetics

III. Rabeprazole: Proton pump inhibitor

IV. Amyl nitrite: Vasodilator

a) I, III

b) II, III, IV

c) III, IV

d) I, II, III

Q.7 Number of chiral carbons present in the structure of Cyproheptadine?

a) 1

b) 3

c) 4

d) 0



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


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