Phenylephrine (HCl)

Phenylephrine (HCl) is direct acting sympathomimetic agent. its effects are similar to those of norepinephrine, but it is less potent and has a longer duration of action. Phenylephrine (HCl) is a vasoconstrictor (constrict blood vessels) and causes rise in blood pressure. It is used as a nasal decongestant. It promotes nasal drainage and relieves nasal stiffness. itused to relieve symptoms associated with sinus infections, cold, hay fever and allergies.


Adult Dose
Dose: 0.25 to 0.5 %
Single Dose: 0.38 (0.375)
Frequency: 4 hourly
Route: Nasal
Instructions: As Required
Neonatal
Dose:
Single Dose:
Frequency:
Route:
Instructions: Not recommended in this age group
Paedriatic
Dose: 0.25 to 0.5 %
Single Dose: 0.38 (0.375)
Frequency: 4 hourly
Route: Nasal
Instructions: As Required
Characteristics
Phenylephrine is the derivative of Phenylephrine (HCl). It is of Synthetic origin and belongs to Aminoethanol. It belongs to Alpha adrenergic agonist pharmacological group on the basis of mechanism of action and also classified in Drugs used in Shock and Alpha-Beta Blocker pharmacological group.The Molecular Weight of Phenylephrine (HCl) is 203.70. It is weakly acidic drug, 3.00% solution of the drug is isotonic and Its pKa is 8.9, 10.1.
Contraindications
Phenylephrine (HCl) is contraindicated in conditions like Angina,Hypertension,Hyperthyroidism,Myocardial infarction.
Effects
Phenylephrine (HCl) produces potentially life-threatening effects which include Bradycardia, Vomiting, Severe hypertension. which are responsible for the discontinuation of Phenylephrine (HCl) therapy.The signs and symptoms that are produced after the acute overdosage of Phenylephrine (HCl) include Bradycardia, Rise in B.P..
Indications
Phenylephrine (HCl) is primarily indicated in conditions like Acid-related dyspepsia, Congestion, Hypotension.
Interactions
Phenylephrine (HCl) is known to interact with other drugs, the details of drug interactions is as follows:DrugDetailsSeverityOnsetManagementAcebutololAdrenalineDoxepin (HCl)Ergotamine (Tartrate)Ergotamine significantly increases the blood pressure by synergistic vasoconstriction due to alpha adrenergic agonist activity of phenylephrine.ModerateClinical monitoring of response, tolerence and excessive vasoconstriction is recommended. Patient advised to notify if numbness,tingling,muscle pain,weakness and chest pain signs appears.GuanethidineGuanethidine work by depleting catecholamines stores from adrenergic nerve endings so its hypotensive effect is decresase by phenylephrine whose pharmacological effect is increased by guanethidine.ModerateMonitoring of blood pressure and heart rate is must if this combination is used.In hypertensive patients noradrenaline is used with caution.MethylamphetamineCentral nervous system (CNS) stimulants, particularly the amphetamines, can potentiate the adrenergic response to pressor agents. CNS stimulants often have peripheral sympathetic activity and can increase blood pressure and heart rate, thus they may have additive effects with pressor agents.ModerateCaution is advised if CNS stimulants are used with pressor agents. Pulse and blood pressure should be closely monitored. MethyldopaMethylergonovineErgot alkaloids may cause a significant increase in blood pressure when combined with peripheral or central vasoconstrictors. The mechanism is an additive or synergistic vasoconstriction due to the alpha adrenergic agonist activity of ergot alkaloids. ModerateThe use of dihydroergotamine injection or nasal spray with vasoconstrictive agents is not recommended and other ergot alkaloids should be administered with caution. Clinical monitoring of patients response and tolerance, including measurements of vital signs and monitoring for excessive vasoconstriction, is recommended if these products are used in combination. Patients should be advised to notify their doctor if they experience numbness, tingling, or cyanosis in the extremities, muscle pains, weakness, or chest pain or tightness. MoclobemideRauwolfia ReserpineTranylcypromine (Sulphate)Phenylephrine precipitate the hypertensive crises associated with tranylcypromine by acting synergistically to enhanced norepinephrine storage in adrenergic neurons and increases secretion of catecholamines.MajorCoadministration is considered contraindicated. There should be gap of atleast 14 days between initiation of therapy with phenylephrine and discontinuing tranylcypromine.Trimipramine (Maleate) These interactions are sometimes beneficial and sometimes may pose threats to life. Always consult your physician for the change of dose regimen or an alternative drug of choice that may strictly be required.
Interfrence
False elevation of VMA test for catecholamines
Risks
Drug should not be given to Paediatrics, Pregnant Mothers, Geriatrics, and Neonates.If prescribing authority justifies the benefits of the drug against the possible damages he/she should reevaluate them and consult the reference material and previous studies.
Storage
Inj Store at room temperature. Do not Freeze. Protect from Sunlight. Nasal Spray, Nasal Drops, Eye Soln Store Below 40°C. Do not Freeze. Protect from Sunlight.
Warnings
Phenylephrine should be used with caution in patients with hyperthyroidism, bradycardia, partial heart block. It should be used in large vein to avoid necrosis and sloughing of surrounding tissues. Phenylephrine 10% eye drops should be avoided or only used with extreme caution in infants and the elderly.
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