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]]>3-[(4,5-Dihydro-1H-imidazol-2-ylmethyl)(4-methylphenyl)amino]phenol.
Phentolamine is nonselective α-adrenergic antagonist. It can also be categorize as an antidote.
S. NO. | PHYSICAL AND CHEMICAL PROPERTIES | |
1 | Molecular weight | 281.35 g/mol |
2 | Physical appearance | Present in crystalline solid form |
3 | Melting point | 174.5°C |
4 | Solubility | 4.59 mg/L in water |
5 | Octanol/water partition coefficient | 3.3 |
6 | Presence of ring | Benzene and imidazoline rings are present |
7 | Number of chiral centers | Not present |
i. Phentolamine competitively blocks α-adrenergic receptors.
ii. It leads to relaxation of muscles and widening of blood vessels.
iii. Widening of blood vessels results in decrease in blood pressure.
Phentolamine also stimulates ß-adrenergic receptors and produces a positive inotropic and chronotropic effect on the heart which results in increase in the cardiac output. [1]
m-(p-toluidino)phenol is refluxed with 2-chloromethylimidazoline to give phentolamine.
Phentolamine is used for:
Side Effects
Side effects of Phentolamine are:
MCQs
Q.1 What can be the correct IUPAC nomenclature of Phentolamine
a) 3-[(4,5-Dihydro-1H-imidazol-2-ylmethyl)(4-methylphenyl)amino]phenol
b) 3-[(1R,2S)-2-amino-1-hydroxypropyl]phenol
c) 2-(naphthalen-1-ylmethyl)-4,5-dihydro-1H-imidazole
d) (RS)-4-(2-{[4-(4-hydroxyphenyl)butan-2-yl]amino}ethyl)benzene-1,2-diol
Q.2 Which amongst the following statements is/are correct related to the SAR of phentolamine?
I. Molecules with 2,6-disubstitutions, which assume an orientation where the phenyl and imidazoline rings are in different plans are having the a highest activity.
II. Electronic effects have only influence on the actions at H2; action on α-receptors are not influenced.
III. Substitutions at 3, 4 or 5 positions of the phenyl ring preclude potent activity at H2-receptor sites while the ↑-receptor activity is maintained.
a) I, II
b) I, II, III
c) II, III
d) I
Q.3 m-(p-toluidino)phenol is refluxed with 2-chloromethylimidazoline to give?
a) Dobutamine
b) Sildosin
c) Phentolamine
d) Mthacholine
Q.4 Side effects of drug phentolamine is/are?
a) change in heart rate
b) Headache
c) Dizziness
d) All of the above
Q.5 Match the following drugs with their correct melting points-
i. Phentolamine | A. 184-186°C |
ii. Dobutamine | B. 174.5°C |
iii. Metaraminol | C. 257°C |
iv. Naphazoline | D. 107.5°C |
a) i-D, ii-B, iii-A, iv-C
b) i-A, ii-D, iii-C, iv-B
c) i-C, ii-B, iii-D, iv-A
d) i-B, ii-A, iii-D, iv-C
Q.6 An example of drug from class nonselective α-adrenergic antagonist?
a) Metaraminol
b) Dopamine
c) Albuterol
d) Phentolamine
Q.7 The type of ring system found in Phentolamine?
a) Imidazoline
b) Ergorine
c) Cyclopropane
d) None of the above
1-a
2-b
3-c
4-d
5-d
6-d
7-a
REFERENCES
[1] Gould LA, Zahir MO, Ettinger ST. Phentolamine and cardiovascular performance. British heart journal. 1969 Mar;31(2):154. [2] Malta E, Ong JS, Raper C, Tawa PE, Vaughan GN. Structure-activity relationships of clonidine-and tolazoline-like compounds at histamine and alpha-adrenoceptor sites. British journal of pharmacology. 1980 Aug;69(4):679.The post PHENTOLAMINE 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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