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]]>7-Chloro-5-(2-chlorophenyl)-3-hydroxy-1,3-dihydro-1,4-benzodiazepin-2-one
Lorazepam is a benzodiazepine sedative-hypnotic.
S. NO. | PHYSICAL AND CHEMICAL PROPERTIES | |
1 | Molecular weight | 321.2 g/mol |
2 | Physical appearance | Solid |
3 | Melting point | 167°C |
4 | Octanol/water partition coefficient | 2.39 |
5 | Solubility | 80 mg/ml |
6 | Presence of ring | Diazepine, benzene |
7 | Number of chiral centers | Not present |
i. Lorazepam binds allosterically with the benzodiazepine receptor present in the post synaptic GABAA at different sites in CNS.
ii. This results in increases of the GABA inhibitory effects.
iii. Flow of chloride ions into the cell increases and hyperpolarization of cell takes place.
iv. Lorazeam binds in the amygdale to help in anxiety, while binding of the drug in cerebral cortex helps in seizure disorders.
i. Reaction of 2-amino-2’5-dichlorobenzophenone (1) with hydroxylamine gives (2).
ii. (2) on reaction with chloroacetyl chloride and fter heterocyclization gives 6-chloro-2-chlormethyl-4-(2’-chlorphenyl)quinazolin-3-oxide (3)
iii. On reaction of (3) with methylamine leads to thering expansion and formation of 7-chloro-2-methylamino-5-(2’-chlorphenyl)-3H-1,4-benzodiazepin-4-oxide (4).
iv. On aetylation on secondary nitrogen using acetic anhydride, followed by hydrolysis by hydrochloric acid give 7-chloro-5-(2’-chlorphenyl)-1,2-dihydro-3H-1,4-benzodiazepin-2-on-4-oxide (5).
v. On further reaction with acetic anhydride, the compound will undergo Polonovski type rearrangement reaction to produce 3-acetoxylated benzodiazepine, 7-chloro-1,3-dihydro-3-acetoxy-5-(2′-chlorphenyl)-2H-benzodiazepin-2-one (6).
vi. Hydrolysis of (6) will yield lorazepam. [2]
Lorazepam is used for:
Side Effects
Side effects of Lorazepam are:
Q.1 Correct statements related to the physicochemical properties of drug Lorazepam are?
I. Molecular weight: 299.75 gm/mol
II. Present in solid form at NTP.
III. Octanol/water partition coefficient is 4.4
IV. No chiral carbon atoms are present in structure
a) I, II
b) I II, III
c) II, IV
d) II, IV
Q.2 Match the following of the drugs with their correct IUPAC names.
i. Flavoxate | A. 2-(1-piperidyl)ethyl 3-methyl-4-oxo-2-phenylchromene-8-carboxylate |
ii. Eszopiclone | B. 7-Chloro-5-(2-chlorophenyl)-3-hydroxy-1,3-dihydro-1,4-benzodiazepin-2-one |
iii. Chlordiazepoxide | C. 7-Chloro-2-methylamino-5-phenyl-3H-1,4-benzodiazepine-4-oxide |
iv. Lorazepam | D. (S)-(+)-6-(5-Chloro-2-pyridinyl)-7-oxo-6,7-dihydro-5H-pyrrolo[3,4-b]pyrazin-5-yl-4-methyl-1-piperazinecarboxylate |
a) i-B, ii-C, iii-A, iv-D
b) i-D, ii-A, iii-B, iv-C
c) i-A, ii-B, iii-C, iv-D
d) i-A, ii-D, iii-C, iv-B
Q.3 Correct steps for the mechanism of action of the drug Lorazepam?
I. Binding with GABAA receptors
II. Increase the Binding of GABA to the GABAA receptors
III. Decreases of the binding of GABA to the GABAA receptors
IV.Enhancement of the GABA mediated chloride influx
a) I – III – IV
b) I – IV – II
c) II – III – IV
d) I – II – IV
Q.4 Correct sequence for True/false for the classification of the drug can be?
a) TTFT
b) FFTT
c) FTFT
d) TFTT
Q.5 When there is substitution at the ortho position of the ring C of Lorazepam-
a) No change observed in agonist property
b) Agonist property increases by 2-fold
c) Agonist property decreases by 2-fold
d) Agonist property increases by !.5-fold
Q.6 Types of ring structure present in Lorazepam ?
I. Chromine
II. Benzene
III. Piperidine
IV. Diazepine
a) I, II, III, IV
b) II, IV
c) I, III
d) I, II, III
Q.7 Side effect of drug Lorazepam?
a) Dizziness
b) Constipation
c) Blurred vision
d) All of the above
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1-d
2-d
3-d
4-c
5-a
6-b
7-d
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