Due to the fact that alpha 1 receptors are blocked, vasodilatation occurs and blood flow to periphery is increased, while venous return is decreased. The condition can be diagnosed by 3 hydroxy 4 methoxymandelic acid or by the presence of metabolites in urine or by using radio-isotopes, CT scan or MRI. FIFA 16 Legend https://fut16coin.wordpress.com/2015/06/29/fifa-... Fut 16 coins: What is with that guy? Selective Alpha Blockers. They are classified according to the receptor sensitivity. They simply result in some symptomatic relief by yielding reduced mechanical pressure on the urethra. Newer agents like Tamsulosin (alpha 1 a) are highly effective, especially in non-hypertensive patients. If given in excess, to reverse the effects, alpha blockers are given to block the vasoconstrictor effects. When alpha 1 receptors are blocked, sphincters are opened, leading to increased motility, which may cause diarrhea and vomiting. Drugs Acting on Eye, Respiratory System and Miscellaneous Drugs, Browse all articles on Autonomic Nervous System, Piperazine Citrate and Diethylcarbamazine -Antihelminthic Drugs, Vinca Alkaloids, Taxanes, Epipodophyllotoxins, Camptothecins, Hormones, Anti-hormones, Asparaginase, Monoclonal Antibodies and Cytokines, Methotrexate, 5-Fluorouracil, Purine Antagonists and Antibiotics Used in Cancer Chemotherapy, Ziehl Neelsen Staining -Principle, Procedure and Interpretations. Baseline alpha1 tone in the smooth muscle of the bladder neck and the prostate appears is responsible for some mechanical pressure on the urethra traveling through these regions. (Labetolol is more efficient as is more selective, Urapidil may be used as well) Alpha blockers are not the first line of defense. Metyrosine decreases the synthesis of adrenaline and noradrenaline. * Alpha-1 Receptor Anatgonist Reflex tachycardia is less significant Prazosin related drugs: Terazosin, doxazosin CVS effects: ↓ peripheral resistance and lowers blood pressure Therapeutic indications: Hypertension Benign prostate hypertrophy Adverse effects: Dizziness, nasal congestion, head ache, drowsiness, orthostatic hypotension Some alpha-blockers are non-competitive (e.g., phenoxybenzamine), which greatly … However, carvedilol does NOT cause reflex tachycardia even though it is an alpha-1 blocker. This has no therapeutic importance. In most patients this results in reduced systemic arterial pressure. Phenoxybenzamine is given preoperatively in 10-20 mg/day dose a few days before starting surgery. Doxazosin: Terazosin. Alpha1-specific adrenergic antagonists are compounds that antagonize with high specificity the alpha1 subtype of adrenergic receptors. It is important to point out that these drugs do not alter the fundamental hyperplastic pathology of BPH or its natural course. One would predict that such an effect would result in a reflex tachycardia, which is routinely observed for most other arterial vasodilators such as non-selective alpha blockers (e.g. In mild to moderate hypertension, Prazosin (short acting) is used. The sympathetic system starts from the central nervous system and reaches the ganglia and then the adrenergic neurons, where neurotransmitters are released (nor-adrenaline). Alpha1 blockers are infrequently used as monotherapy for. Effective hypertensive emergency must be coped with. • Reflex tachycardia . increased sympathetic outflow can cause direct tachycardia by the stimulation of beta 1 receptors on the heart. Because prazosin is selective for inhibiting α 1 adrenergic receptors, it will lower arterial blood pressure by blocking postsynaptic α 1 receptors on arterial smooth muscle. Alpha 1 receptors are also found in the base of bladder and neck of prostate. Useful clinically in urinary retention due to BPH. Alpha 1 receptors are mainly present in most of the smooth muscles, piloerector, papillodilator muscles and the heart. Alpha Adrenergic Blockers (Alpha Antagonists) 1. This is not considered appropriate for operation and refractory cases. Indication is also seen in sudden withdrawal of Clonidine. Nasal Stuffiness. Thus blood pressure is not maintained and stretch of vessels in region of trigeminal nerve supply lead to migraine. Alpha 2 blockers (non-selective alpha blockers) are seen more to cause reflex tachycardia. Vasodilatation within mucous membrane of nasopharynx occurs, causing nasal stuffiness. a. A decrease in pressure is observed leading to decreased mechanical resistance to flow of urine.