Alpha adrenergic receptor

Alpha adrenergic receptor

Q. 1 Alpha 1 blocker used for BHP is:
 A Tamsolusin
 B Prazosin
 C Oxazosin
 D Dolazoline
Q. 1 Alpha 1 blocker used for BHP is:
 A Tamsolusin
 B Prazosin
 C Oxazosin
 D Dolazoline
Ans. A

Explanation:

Tamsolusin


Q. 2 Alpha 1 blocker used for BHP without any effect on blood pressure is:
 A Tamsolusin
 B Terazosin
 C Oxazosin
 D Dolazoline
Q. 2 Alpha 1 blocker used for BHP without any effect on blood pressure is:
 A Tamsolusin
 B Terazosin
 C Oxazosin
 D Dolazoline
Ans. A

Explanation:

Tamsolusin


Q. 3

Which of the following is an Alpha la adrenergic blocker which give symptomatic relief in BPH?

 A

Tamsulosin

 B

Prazosin

 C

Oxazocin

 D

Dolazoline

Q. 3

Which of the following is an Alpha la adrenergic blocker which give symptomatic relief in BPH?

 A

Tamsulosin

 B

Prazosin

 C

Oxazocin

 D

Dolazoline

Ans. A

Explanation:

Alpha 1A receptor is predominantly found in bladder base and prostate. Tamsulosin is a uroselective alpha1 blocker effective for symptomatic relief in BPH.

Prazosin is a highly selective alpha 1 blocker having alpha1: alpha 2 selectivity ratio 1000:1. It blocks alpha 1 receptors in bladder trigone and prostate and improves urine flow and reduces residual urine in bladder in a case of BPH.

Quiz In Between


Q. 4

Which of the following is an Alpha 1 blocker without any effect on blood pressure?

 A

Tamsulosin

 B

Prazosin

 C

Oxazocin

 D

Terazocin

Q. 4

Which of the following is an Alpha 1 blocker without any effect on blood pressure?

 A

Tamsulosin

 B

Prazosin

 C

Oxazocin

 D

Terazocin

Ans. A

Explanation:

Tamsulosin a nonquinazoline, is a long acting selective alpha 1A adrenergic receptor antagonist.

Tamsulosin and its metabolites are most specific for prostatic alpha 1A adrenergic receptor and less specific for vascular alpha 1A adrenergic receptor thereby having less effect on blood pressure.

It is very effective for treating bladder outlet obstruction associated with BPH.


Q. 5

Which of the following alpha blocker is useful in BPH?

 A

Phentolamine

 B

Prazosin

 C

Tolazoline

 D

Phenoxybenzamine

Q. 5

Which of the following alpha blocker is useful in BPH?

 A

Phentolamine

 B

Prazosin

 C

Tolazoline

 D

Phenoxybenzamine

Ans. B

Explanation:

BPH is treated with the alpha-blocker terazosin, prazosin, or doxazosin to relax the prostate, and finasteride or dutasteride to decrease the mass of the prostate.

Must know:
  • Prazosin is a peripheral acting alpha-adrenergic blocker used primarily to treat hypertension.
  • Phentolamine is an α-adrenergic blocker used for controlled hypotension, treatment of perioperative hypertensive crisis that may accompany pheochromocytoma removal, prevention or treatment of dermal necrosis or sloughing after intravenous administration or extravasation of barbiturate or sympathomimetic.
  • Tolazoline is a competitive α1 and α2 adrenergic blocking agent. It also relaxes vascular smooth muscles, producing a peripheral vasodilatation.
  • Phenoxybenzamine is an irreversible, non-competitive α1 and α2 adrenergic receptor antagonist which decreases vascular resistance and lowers both the supine and the standing blood pressure.

Ref: Essentials of Pharmacology for Health Occupations By Ruth Woodrow, Bruce J. Colbert, David M. Smith, 2010, Page 474; Advanced Therapy of Prostate Disease By Martin I. Resnick, Ian Murchie Thompson, 2000, Page 533; Goodman and Gillman’s, 11th edition, Page 172,173,183.


Q. 6

Dale’s vasomotor reversal is due to –

 A

Alpha blocker

 B

Beta blocker

 C

ACH inhibitor

 D

All of the above

Q. 6

Dale’s vasomotor reversal is due to –

 A

Alpha blocker

 B

Beta blocker

 C

ACH inhibitor

 D

All of the above

Ans. A

Explanation:

Ans. is ‘a’ i.e., Alpha blocker

o In Dale’s vasomotor reversal

Neurotransmitter —> Adr

Blockade —> a – receptors

Stimulation —> [32-receptors

o Re-reversal of vosomotor reversal is due to propranolol ((3-blockers).

Quiz In Between


Q. 7

All are alpha blocker except –

 A

Atenolol

 B

Prazosin

 C

Indoramine

 D

Idazoxan

Q. 7

All are alpha blocker except –

 A

Atenolol

 B

Prazosin

 C

Indoramine

 D

Idazoxan

Ans. A

Explanation:

Ans. is ‘a’ i.e., Atenolol


Q. 8

Alpha 1 blocker without any effect on blood pressure is?

 A

Tamsulosin

 B

Prazosin

 C

Oxazocin

 D

Terazocin

Q. 8

Alpha 1 blocker without any effect on blood pressure is?

 A

Tamsulosin

 B

Prazosin

 C

Oxazocin

 D

Terazocin

Ans. A

Explanation:

Ans. is ‘a’ i.e., Tamsulosin

o Tamsulosin is selective for aiA receptors which are found predominantly on prostate and bladder.

It does not act on ai B receptors which are found predominanly on blood vessels. Therefore, it has littel effect on BP.


Q. 9

Alpha la adrenergic blocker giving symptomatic relief in BPH?

 A

Tamsulosin

 B

Prazosin

 C

Oxazocin

 D

Dolazoline

Q. 9

Alpha la adrenergic blocker giving symptomatic relief in BPH?

 A

Tamsulosin

 B

Prazosin

 C

Oxazocin

 D

Dolazoline

Ans. A

Explanation:

Ans. is ‘a’ i.e., Tamsulosin

Tamsulosine is a uroselective blocker (α1A blocker)

  • It decreases the tone of smooth muscle in bladder trigone, sphincter and prostate → urine flow in patient with BHP is improved.

Quiz In Between


Q. 10

Wrong about clonidine is –

 A

Alpha 2 receptor agonist

 B

First line for AMID

 C

Sudden withdrawal causes rebound hypertension

 D

Controls loose motions due to diabetic neuropathy

Q. 10

Wrong about clonidine is –

 A

Alpha 2 receptor agonist

 B

First line for AMID

 C

Sudden withdrawal causes rebound hypertension

 D

Controls loose motions due to diabetic neuropathy

Ans. B

Explanation:

Ans. is ‘b’ i.e., First line for ADHD

o Behavioural therapy is the first line therapy for the treatment of ADHD. The first line drug for ADHD is Methylpheni date.

o Clonidine is a partial agonist with high affinity and high intrinsic activity at α2 receptors.

  • Sudden withdrawal of clonidine may cause life threatening hypertensive crisis.

o Clonidine is used to control loose motions due to diabetic neuropathy. It may be acting by α2 receptor mediated enhancement of salt absorption in gut mucosa.


Q. 11

In a hypertensive patient with glaucoma which of the following is not used:

 A

Dipivefrine

 B

Alpha blocker

 C

Alpha agonist

 D

Laser trabeculoplasty

Q. 11

In a hypertensive patient with glaucoma which of the following is not used:

 A

Dipivefrine

 B

Alpha blocker

 C

Alpha agonist

 D

Laser trabeculoplasty

Ans. A

Explanation:

Ans. Dipivefrine


Q. 12

Alpha agonist has all of the following actions except:

September 2009

 A

Hypotension

 B

Hypertension

 C

General anesthesia

 D

Nasal decongestant

Q. 12

Alpha agonist has all of the following actions except:

September 2009

 A

Hypotension

 B

Hypertension

 C

General anesthesia

 D

Nasal decongestant

Ans. C

Explanation:

Ans. C: General Anesthesia

Alpha-adrenoceptor agonists bind to alpha-receptors on vascular smooth muscle and induce smooth contraction and vasoconstriction, thus mimicking the effects of sympathetic adrenergic nerve activation to the blood vessels. Vascular smooth muscle has two types of alpha-adrenoceptors: alphal and alpha2.

The alphal-adrenoceptors are the predominant alpha-receptor located on vascular smooth muscle.

Depending on the tissue and type of vessel, there are also alpha2-adrenoceptors found on the smooth muscle.

There are also alpha2-adrenoceptors located on the sympathetic nerve terminals that inhibit the release of norepinephrine and therefore act as a feedback mechanism for modulating the release of norepinephrine.

Alpha-agonists constrict both arteries and veins; however, the vasoconstrictor effect is more pronounced in the arterial resistance vessels (small arteries and arterioles).

Alphal-adrenoceptor agonists (systemic vasoconstrictors)

  • Methoxamine
  • Phenylephrine
  • Oxymetazoline
  • Tetrahydralazine
  • Xylometazoline

Methoxamine and phenylephrine are used as pressor agents in treating hypotension and shock.

Oxymetazoline, tetrahydralazine, xylometazoline and some preparations of phenylephrine are used as nasal decongestants.

Alpha2-adrenoceptor agonists (centrally-acting vasodilators)

  • Clonidine
  • Guanabenz
  • Guanfacine
  • Alpha-methyldopa

The alpha2-adrenoceptor agonists are used very occasionally as centrally-acting sympatholytic vasodilators for the treatment of hypertension.

Quiz In Between


Q. 13

Alpha 2 agonist used in glaucoma is ‑

 A

Brimonidine

 B

Timolol

 C

Phenylephrine

 D

Reserpine

Q. 13

Alpha 2 agonist used in glaucoma is ‑

 A

Brimonidine

 B

Timolol

 C

Phenylephrine

 D

Reserpine

Ans. A

Explanation:

Ans. is ‘a’ i.e., Brimonidine


Q. 14

Selective alpha 2 agoinst used in glaucoma

 A

Tirriolol

 B

Epinephrine

 C

Dipivefrine

 D

Brimonidine

Q. 14

Selective alpha 2 agoinst used in glaucoma

 A

Tirriolol

 B

Epinephrine

 C

Dipivefrine

 D

Brimonidine

Ans. D

Explanation:

Ans. is ‘d’ i.e., Brimonidine


Q. 15

Drug with beta adrenergic blocking, with antioxidant, with calcium channel blocking, with alpha 1 antagonist activity is ‑

 A

Esmolol

 B

Carvedilol

 C

Nebivolol

 D

Levobunolol

Q. 15

Drug with beta adrenergic blocking, with antioxidant, with calcium channel blocking, with alpha 1 antagonist activity is ‑

 A

Esmolol

 B

Carvedilol

 C

Nebivolol

 D

Levobunolol

Ans. B

Explanation:

Ans. is ‘b’ i.e., Carvedilol

Carvedilol

  • Carvedilol is a β1 + β2 + α1 adrenoceptor blocker with α : β blocking property of 1 : 9.
  • It has antioxidant and antimitotic property.
  • It produces peripheral vasodilation due to α-1 blockade as well as calcium channel blockade (direct effect).
  • It is used in hypertension and angina.
  • It is used as cardioprotective in CHF.
  • t1/2 is 2-8 hrs.
  • It is eliminated through liver and kidney.
  • It causes orthostatic hypotension.

Quiz In Between


Q. 16

Drug used in refractory glaucoma ‑

 A

Systemic glucocorticoid

 B

ACE inhibitor

 C

Alpha agonist

 D

Beta blocker

Q. 16

Drug used in refractory glaucoma ‑

 A

Systemic glucocorticoid

 B

ACE inhibitor

 C

Alpha agonist

 D

Beta blocker

Ans. C

Explanation:

Ans. is ‘c’ i.e., Alpha agonist

Drug of choice for initial treatment of open angle glaucoma is either an topical β-blocker or topical PG analogue (latanoprost)

It target IOT is not attained either change over to alternative drug or use both concurrently.

In refractory cases (who are not responding to (3-blockers and PG analogues), topical α-agonist (Brimozidine) or topical carbonic anhydrase inhibitor (dorazolamide) is added.

It target IOT is still not attained, laser trabeculoplasty is considered.


Q. 17

The drug shown in the picture below is a ? 

 A

Alpha blocker.

 B

Beta blocker.

 C

Gamma blocker.

 D

None of the above.

Q. 17

The drug shown in the picture below is a ? 

 A

Alpha blocker.

 B

Beta blocker.

 C

Gamma blocker.

 D

None of the above.

Ans. A

Explanation:

Ans:A.)Alpha Blocker.

Prazosin

  • Prazosin is a selective α-1-adrenergic receptor antagonist
  • Indications:
    • For treatment of hypertension, symptomatic benign prostatic hyperplasia, and severe congestive heart failure.
    • May also be used alone or in combination with β-blockers in the preoperative management of signs and symptoms of pheochromocytoma.



Q. 18

Wrong about clonidine is

 A

Alpha 2 receptor agonist

 B

First line for ADHD

 C

Sudden withdrawal causes rebound hypertension

 D

Controls loose motions due to diabetic neuropathy

Q. 18

Wrong about clonidine is

 A

Alpha 2 receptor agonist

 B

First line for ADHD

 C

Sudden withdrawal causes rebound hypertension

 D

Controls loose motions due to diabetic neuropathy

Ans. B

Explanation:

Ans. is ‘b’ i.e., First line for ADHD

o Behavioural therapy is the first line therapy for the treatment ofADHD. The first line drug forADHD is Methylphenidate.

Clonidine

  • It acts (partial agonist) on a2 receptors, especially a24 in brainstem → Stimulation of a2A receptors in medulla (vasomotor centre) → decrease sympathetic outflow → fall in BP and bradycardia (also due to enhanced vagal tone). 
  • a.2, receptor stimulation is responsible for sedation produced by clonidine.
  • Clonidine also binds to a nonadrenergic receptor, imidazoline receptor, which may also mediate antihypertensive effect. 
  • Rilmenidine and moxonidine are selective cerebral imidazoline receptor agonists with little a, action→equivalent antihypertensive action with low sedative property.
  • Rapid i.v. injection of clonidine raises BP transiently due to activation of peripheralpostsynaptic vasoconstrictor a2B receptors at high concentrations so attained. Oral doses producing lower plasma levels cause only fall in BP, because clonidine has lower intrinsic activity on a2t,receptors which predominate in vascular smooth muscle.
  • Uses of clonidine

Hypertension                       Opioid withdrawl            Menopausal syndrome

Alcohal withdrawal               Smoking cessation         Loose motions in diabetic neuropathy

Test for pheochromocytoma

  • Abrupt discontinuation of clonidine therapy can lead to rebound hypertension (treated with phentolamine); therefore this drug is not suitable for people having travelling job like business executives who are likely to miss the doses.

Quiz In Between



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