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]]>2-dimethylallyl-5,9-dimethyl-2′-hydroxybenzomorphan
S. NO. | PHYSICAL AND CHEMICAL PROPERTIES | |
1 | Molecular weight | 285.4 g/mol |
2 | Physical appearance | White to very tan crystalline powder |
3 | Melting point | 145.4-147.2°C |
4 | Solubility | Soluble in acetone; sparingly soluble in ethyl acetate |
5 | Octanol/water partition coefficient | log Kow = 3.31 |
6 | Presence of ring | Piperidine, phenyl |
7 | Number of chiral centers | 1 |
Pentazocine antagonizes the opioid effects by competing at the receptor site. It mainly compete the opioid mu receptor site.
SAR for morphine analogues can be summarized as follows:
i. 3,4-dimethylpyridine undergoes reaction with methyl iodide to produce 1,3,4-trimethylpyridinium iodide.
ii. The above formed compound is then reacted with 4-methoxybenzyl magnesium chloride to give 2-methoxybenzyl-3,4-dimethyl-1,2-dihydropyridine.
iii. Double bond of the last formed compound is hydrogenated using palladium catalyst to produce 3-methoxybenzyl-3,4-dimethyl-1,2,3,4-tetrahydropyridine.
iv. Intramolecular alkyation and simultaneous demethylation of the resulting compound leads to formation of 2-hydroxy-2,5,9-trimethylbenzo-6-morphane.
v. Above formed compound undergoes N-demethylation by cyanogens bromide to form 2-hydroxy-5,9-dimethylbenzo-6-morphane-N-normetazocine.
vi. On alkylation of the resulting product by 1-bromo-3-methyl-2-butene gives pentazocine.[1]
Pentazocine is used for:
Side effects Pentazocine are:
Q.1 Choose the correct option related with the mechanism of action of drug Pentazocine?
a) Acts as Opiate receptor antagonist
b) Mainly Competes with opioid sigma receptors
c) Mainly competes with opioid kappa receptors
d) All of the above
Q.2 Therapeutic use of drug Pentazocine is/are?
a) Treatment of diarrhea
b) As an anesthetic
c) Relieve moderate to severe pain
d) All of the above
Q.3 Which amongst the following are the correct statements with respect to the SAR of drug Pentazocine?
I. Replacement of alcoholic hydroxyl with -OC2H5 makes the compound 2.4 times more active than morphine.
II. Replacement of alcoholic hydroxyl with –OCOCH3 will also activates the compound by 4.2 times.
III. Replacement of alcoholic hydroxyl with ketone group inactivates the compound and makes it lesser active.
IV. By hydrogenation of alicyclic unsaturated linkage, activity increases by 1.2 times
a) I, IV
b) II, III
c) III, IV
d) I, II, III, IV
Q.4 Number of chiral carbons present in the structure of Pentazocine is?
a) 0
b) 1
c) 2
d) 3
Q.5 Correct sequence for the True/False for the physiochemical properties of the drug pentazocine is?
I. Molecular weight = 582 gm/mol
II. Melting point = 110.2oC
III. White to very tan crystalline powder
IV. Ring structure absent
a) FFTF
b) TFFT
c) FTTF
d) TFFF
Q.6 Correct statements for the IUPAC nomenclatures of the drugs are?
I. Pentazocine: 2-dimethylallyl-5,9-dimethyl-2′-hydroxybenzomorphan
II. Mechlorethamine: 2-Chloro-N-(2-chloroethyl)-N-methylethan-1-amine
III. Ifosfemide: N,3-Bis(2-chloroethyl)-1,3,2-oxazaphosphinan-2-amide 2-oxide
IV. Carmustine: 1,3-Bis(2-chloroethyl)-1-nitrosourea
a) I, II
b) I, II, III, IV
c) II , III
d) III, IV
Q.7 Match the following drugs with their correct classifications-
i. Ifosfemide | A. Nitrogen mustard |
ii. Pentazocine | B. Nitrosoureas alkylating agent |
iii. Lomustine | C. Pyrimidine antagonist |
iv. Cytarabine | D. Opioid analgesic |
a) i-B, ii-D, iii-C, iv-A
b) i-B, ii-C, iii-A, iv-D
c) i-C, ii-B, iii-D, iv-A
d) i-A, ii-D, iii-B, iv-C
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1-a
2-c
3-d
4-b
5-a
6-b
7-d
REFERENCES
[1] Vardanyan R, Hruby V. Synthesis of essential drugs. Elsevier; 2006 Mar 10.The post PENTAZOCINE Synthesis, SAR, MCQ,Structure,Chemical Properties and Therapeutic Uses appeared first on Gpatindia: Pharmacy Jobs, Admissions, Scholarships, Conference,Grants, Exam Alerts.
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