Adrenoreceptor Antagonists Flashcards
MoA of Alpha receptor blockers
Prevent the action of NE & E at the a receptors.
Effects of Alpha receptor Blockers
1) ↓ TPR, ↓ mean BP.
2) May cause reflex tachycardia and salt and water retention
Indication of Phentolamine
- Pheochromocytoma
- Antidote to overdose of α agonist
(patients on MAO inhibitors who eat tyramine-containing foods & severe cocaine-induced hypertension)
administration route of Phentolamine
Oral or IV.
–> Duration 2 – 4 h.
=->Short half life
Adverse effects of phentolamine
- Orthostatic hypotension.
- Reflex tachycardia.
category of Phentolamine and Phenoxybenzamine
Nonselective α receptors antagonist
Indication of Phenoxybenzamine
- Pheochromocytoma
- carcinoid.
- Mastocytosis.
Administration route of Phenoxybenzamine
Oral
–> Long half-life of 24 – 48h.
Adverse effects of Phenoxybenzamine
- Orthostatic hypotension.
- Reflex tachycardia.
- GI irritation.
Non-selective α-blockers
Phentolamine and Phenoxybenzamine
Selective α1 receptor antagonists (drugs)
-osin
Prazosin, Doxaosin, Terazosin, Tamsoulosin
indication of Selective α1 receptor antagonists
[Prazosin, Doxaosin, Terazosin, Tamsoulosin]
- Benign prostatic hyperplasia (BPH)
(bladder sphincter relaxation)
(Decreases blood pressure –> Vasodilaion) - PTSD (Prazosin).
- Miosis
Administration of Selective α1 receptor antagonists
[Prazosin, Doxaosin, Terazosin, Tamsoulosin]
- Prazosin –> 8 h duration.
- Doxazosin, terazosin –> 12 – 24 h
duration. - Tamsulosin –> approved for BPH
Adverse effects of Selective α1 receptor antagonists
[Prazosin, Doxaosin, Terazosin, Tamsoulosin]
- Orthostatic hypotension (1st does).
- Little reflex tachycardia
a drug that is a selective a2 receptor antagonist
Yohimbine
Adverse effects of Yohimbine
- Tachycardia.
- GI upset.
Administation route of Yohimbine
oral or parenteral.
Indication of Yohimbine
erectile dysfunction
MoA of Beta receptor blockers
Inhibit the action of catecholamines at beta receptors
- End in -olol
Effects of Beta receptor blockers
1) β1 – blockade:
* ↓ HR, ↓CO, ↓ SV.
* ↓ renin release.
2) Cardioselectivity: (β1)
* Less effect on vasculature, bronchioles, uterus, and metabolism.
* Safer in asthma, diabetes, peripheral vascular diseases.
3) β2 – blockade;
* Respiratory effects;
–> May precipitate bronchospasm (in asthmatics)
–> Vasospasm (in patients with vasospastic disorders)
4) Effects on eye:
*↓ aqueous humor production.
5) Metabolic effects:
* Blocks glycogenolysis, gluconeogenesis &
↓ lipolysis (β3) [↑ LDLs, ↑ TGs]
Νοn-selective β-blockers
Propranolol, Timolol
Β1 selective blockers
Atenolol, Metoprolol
Combined α + β-blocker
Labtalol, Carvedilol
Indication of Propranolol
1) Angina
2) Arrythmia (tx and prophylaxis)
3)Hypertension
4) Thyrotoxicosis
5) tremor
6) Performance anxiety
7) migraine
Administration route of Propranolol
Oral and IV –> Can enter CNS
Adverse effects of Propranolol
Excessive β-block:
- Bronchospasm
- AV block
- HF
- CNS sedation, lethargy,
sleep disturbance
Indication of Atenolol & Metoprolol?
Hypertension, Angina, Arrythmia
Administration of Atenolol & Metoprolol?
Oral administration
Adverse effects of Atenolol & Metoprolol?
1) Bronchospasm
2) Hypotension
3) Bradycardia
4) Heart failure
5) AV block
6) Respiratory Distress (allergic)
Indication of Timolol
Glaucoma
MoA of Timolol
↓AH formation
* AH: aqouea humour
Indication of Labetalol
Hypertensive emergency
Administration of Labtalol
Oral and IV
Administration of Carvedilol
Oral and IV
Indication of Carvedilol
Congestive Heart Failure
