Brands, Medical Use, Clinical Data
Drug Category
- Adrenergic alpha-Agonists
- Cardiotonic Agents
- Nasal Decongestants
- Sympathomimetics
- Vasoconstrictor Agents
- Mydriatics
Dosage Forms
- Ophthalmic solution
- Nasal solution
- Solution (IM, IV, IV infusion and subcutaneous)
- Gel
- Cream
- Ointment
- Suppository
Brands / Synonyms
Adrianol; Airacof; AK-Dilate; AK-Nefrin; Alcon Efrin; Alconefrin Nasal Drops 12; Alconefrin Nasal Drops 25; Alconefrin Nasal Drops 50; Alconefrin Nasal Spray 25; Biomydrin; Bromhist; Chlorphenylcaine; Crantex; Cyclomydril; Dallergy; Dihydrocodeine BPM Phenyleph; Dilatair; Dimetane; Dionephrine; Doktors; Donatuss; DUO-Medihaler; Duration; Extendryl; Fenilefrina [Inn-Spanish]; Hycomine; I-Phrine; Isophrim; Isophrin; Isopto Frin; L-Phenylephedrine; L-Phenylephrine; M-Methylaminoethanolphenol; M-Oxedrine; M-Sympathol; M-Sympatol; M-Synephrine; Mesaton; Mesatone; Mesatonum; Metaoxedrin; Metaoxedrine; Metaoxedrinum; Metasympatol; Metasynephrine; Metsatonum; Mezaton; Minims Phenylephrine; Mydfrin; Neo-Synephrine; Neo-Synephrine Nasal Drops; Neo-Synephrine Nasal Jelly; Neo-Synephrine Nasal Spray; Neofrin; Neophryn; Neosynephrine; Nostril; Nostril Spray Pump; Nostril Spray Pump Mild; Ocu-Phrin Sterile Eye Drops; Ocugestrin; Phenoptic; Phenylephrine, I-; Phenylephrine, L-; Phenylephrinhydrochlorid; Phenylephrinum [Inn-Latin]; Prefrin; Prefrin Liquifilm; Promethazine and Phenylephrine; Promethazine VC; Promethazine, Phenylephrine and Codeine; Pyracort D; Relief Eye Drops for Red Eyes; Rhinall; Spersaphrine; Vicks Sinex; Visadron
Indications
For the treatment of ophthalmic disorders (hyperaemia of conjunctiva, posterior synechiae, acute atopic), nasal congestion, hemorrhoids, hypotension, shock, hypotension during spinal anesthesia, paroxysmal supraventricular tachycardia. It is also used as an aid in the diagnosis of heart murmurs and for prolongation of spinal anesthesia
Pharmacology
Phenylephrine is a powerful vasoconstrictor. It is used as a mydriatic, nasal decongestant, and cardiotonic agent. Phenylephrine is a postsynaptic alpha-receptor stimulant with little effect on the beta receptors of the heart. Parenteral administration of Phenylephrine causes a rise in systolic and diastolic pressures, cardiac output is slightly decreased and peripheral resistance is considerably increased, most vascular beds are constricted; renal, splanchnic, cutaneous, and limb blood flows are reduced but coronary blood flow is increased. Pulmonary vessels are constricted, and pulmonary arterial pressure is raised. This alpha receptor sympathetic agonist is also used locally because its vasoconstrictor and mydriatic action.
Mechanism of Action
Phenylephrine produces its ophthalmic and systemic actions by acting on alpha 1 adrenergic receptors in the pupillary dilator muscle and the vascular smooth musle, resulting in contraction of the dilator muscle and contraction of the smooth muscle in the arterioles of the conjunctiva and peripheral vasoconstriction. Phenylephrine decreases nasal congestion by acting on alpha 1 adrenergic receptors in the arterioles of the nasal mucosa to produce constriction.
Absorption
Reduced bioavailability (compared to pseudoephedrine) following oral administration due to significant first-pass metabolism.
Toxicity
Not Available
Biotrnasformation / Drug Metabolism
Oral phenylephrine is extensively metabolised by monoamine oxidase, an enzyme which is present in the stomach and liver.
Contraindications
Phenylephrine hydrochloride should not be used in patients with severe hypertension, ventricular tachycardia, or
in patients who are hypersensitive to it or to any of the components.
Drug Interactions
Vasopressors, particularly metaraminol, may cause serious cardiac arrhythmias during halothane anesthesia and
therefore should be used only with great caution or not at all.
MAO Inhibitors
The pressor effect of sympathomimetic pressor amines is markedly potentiated in patients receiving monoamine
oxidase inhibitors (MAOI). Therefore, when initiating pressor therapy in these patients, the initial dose should be
small and used with due caution. The pressor response of adrenergic agents may also be potentiated by tricyclic
antidepressants.
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