Phenylephrine

Oral
Nasal congestion
Adult: 10 mg 4 hourly as needed for up to 7 days. Max: 60 mg daily.
Child: ≥12 years: Same as adult dose.

Nasal
Nasal congestion
Adult: As 0.25-1% solution: Instill 2-3 drops or sprays in each nostril 4 hourly as needed for up to 3 days.
Child: ≥12 years: Same as adult dose.

Parenteral
Hypotensive states
Adult: Mild to moderate: Initially, 2-5 mg as 1% solution via SC/IM, with further doses up to 1-10 mg after at least 15 minutes if necessary. Alternatively,100-500 mcg via slow IV inj as 0.1% solution, repeated as necessary every -15 minutes. Severe: Initially, up to 180 mcg/minute via infusion, adjusted to 30-60 mcg/minute according to response.
Renal impairment: Dosage reduction may be needed.
Reconstitution: IV inj: Dilute 10 mg with 99 mL 5% dextrose or 0.9% NaCl to a concentration of 100 mcg/mL. IV infusion: Add 10 mg in 500 mL 5% dextrose or 0.9% NaCl to a concentration of 20 mcg/mL.

Intravenous
Paroxysmal supraventricular tachycardia
Adult: Initially, up to 500 mcg via rapid injection (within 20-30 seconds), increased in increments of 100-200 mcg up to Max of 1 mg, if necessary.
Reconstitution: IV inj: Dilute 10 mg with 99 mL 5% dextrose or 0.9% NaCl to a concentration of 100 mcg/mL. IV infusion: Add 10 mg in 500 mL 5% dextrose or 0.9% NaCl to a concentration of 20 mcg/mL.

Ophthalmic
Production of mydriasis
Adult: As 2.5 or 10% eye drop solution: instill 1 drop to each eye prior to procedure; a drop of local anaesthetic may be administered few minutes before instillation of phenylephrine. If necessary, repeat dose once only after at least 1 hour. Max: 3 drops per eye.
Child: As 2.5% eye drop solution: Instill 1 drop to each eye. Max: 3 drops per eye. As 2.5% eye drop solution: Instill 1 drop to each eye. Max: 3 drops per eye.

Rectal
Haemorrhoids
Adult: As 0.25% cream/gel/ointment either as single component or in combination with other anorectal agents: Apply to clean, dry area up to 4 times daily. As 0.25% supp: Insert 1 supp up to 4 times daily. Max: 2 mg daily.
Child: ≥12 years: Same as adult dose.

Should be taken with food.

Severe hypertension, ventricular tachycardia, severe hyperthyroidism. Ophthalmic (10% solution): Close-angle glaucoma. Children and elderly. Cold preparations should not be used in children <2 years. Concomitant or within 14 days of MAOI use (oral).

Patient with CV disease (e.g. ischaemic heart disease, pre-existing bradycardia, partial heart block, severe coronary artery disease, heart failure, cardiogenic shock), diabetes mellitus, asthma, arteriosclerosis, aneurysm, hypertension, narrow-angle glaucoma. Renal impairment (IV). Children. Elderly. Pregnancy (especially those with history of pre-eclampsia) and lactation. Patient Counselling Eye drops may cause temporary blurring of vision, if affected, do not drive or operate machinery. Monitoring Parameters Monitor blood pressure.

Significant: Reflex bradycardia, extravasation (IV); rebound miosis (ophthalmic); Cardiac disorders: Arrhythmia, ischemia, extrasystoles, palpitation, tachycardia. Eye disorders: Eye pain, irritation, stinging or burning sensation, blurred vision, photophobia, mydriasis, vitreous opacity (transient). Gastrointestinal disorders: Nausea, vomiting. Nervous system disorders: Headache, paresthesia,tremor, weakness. Psychiatric disorders: Anxiety, agitation, insomnia, nervousness, excitability. Renal and urinary disorders: Urinary retention (in males). Respiratory, thoracic and mediastinal disorders:Skin and subcutaneous tissue disorders: Blanching of skin, pallor, piloerection. Vascular disorders: Hypertension, hypertensive crisis.
Potentially Fatal: Cerebral haemorrhage, ventricular arrhythmia, myocardial infarction.

Symptoms: Headache, nausea, vomiting, paranoid psychosis, hallucinations, seizures, cerebral haemorrhage, palpitation, paraesthesia, reflex bradycardia, cardiac arrhythmia (e.g. ventricular tachycardia and extrasystoles), sensation of fullness in the head and tingling of extremities. Management: Symptomatic and supportive treatment. α-adrenergic blockers (e.g. phentolamine) may be used to treat severe hypertension.

Concomitant use with adrenergic blocking agents (e.g. phentolamine), phenothiazine drugs (e.g. chlorpromazine) and amiodarone may cause antagonistic effects. May potentiate pressor effects of oxytocic drugs and CV depressant effects of inhalational anaesthetics (e.g. cyclopropane, halothane). May increase risk of arrythmias with cardiac glycosides and quinidine. May enhance the effects of anticholinergic drugs (e.g. TCAs).
Potentially Fatal: Concomitant use with MAOIs (or within 14 days of stopping MAOIs) may result in paroxysmal hypertension and fatal hyperthermia.

Phenylephrine is a sympathomimetic amine that has direct effect on α-adrenergic receptors and an indirect effect of releasing norepinephrine from its storage sites. Its main effect is systemic arterial vasoconstriction. Additionally, it produces local vasoconstriction on dilated arterioles of the conjunctiva and nasal mucosa.
Onset: Immediate (IV); 10-15 minutes (IM/SC); 15-20 minutes (oral); Ophthalmic: 15 minutes (mydriasis), 20-90 minutes (maximal mydriasis), 3-8 hours (time to recovery); ≤2 minutes (intranasal). 15-30 minutes (decongestant)
Duration: Approx 20 minutes (IV); 1-2 hours (IM); approx 1 hour (SC); ≤4 hours (oral); 2.5-4 hours (intranasal, dose dependent).
Absorption: Erratic and incomplete absorption. Readily absorbed (oral). Bioavailability: Approx 40% (oral). Time to peak plasma concentration: 0.75-2 hours; ≤ 20 minutes (ophthalmic).
Distribution: Rapid distribution into peripheral tissues with minimal penetration into the brain. Volume of distribution: 200-500 L (oral).
Metabolism: Metabolised in the liver via sulfate conjugation (oral: 46%, mostly in gutwall; IV: 8%), oxidative deamination (oral: 24%; IV: 50%), and glucuronidation. Undergoes first-pass metabolism in the gut and liver by monoamine oxidase.
Excretion: Via urine (mainly as inactive metabolites). Elimination half-life: Approx 5 minutes (α-phase); 2-3 hours (terminal phase).

Intravenous: Store between 15-25°C. Protect from light. Diluted solution: Refer to product labelling. Nasal: Store between 15-25°C. Protect from light. Ophthalmic: Store between 20-25°C. Protect from light. Some products are refrigerated between 2-8°C, refer to detailed product guidelines. Oral: Store between 15-25°C. Protect from light. Parenteral: Store between 15-25°C. Protect from light. Diluted solution: Refer to product labelling. Rectal: Store between 15-25°C. Protect from light.

Anorectal Preparations / Cough & Cold Preparations / Mydriatic Drugs / Nasal Decongestants & Other Nasal Preparations / Ophthalmic Decongestants, Anesthetics, Anti-Inflammatories / Vasoconstrictors

R01AB01 - phenylephrine ; Belongs to the class of topical sympathomimetic combination preparations, excluding corticosteroids. Used as nasal decongestants.
C01CA06 - phenylephrine ; Belongs to the class of adrenergic and dopaminergic cardiac stimulants excluding glycosides. Used in the treatment of heart failure.
S01GA05 - phenylephrine ; Belongs to the class of sympathomimetics used as ophthalmologic decongestants.
S01FB01 - phenylephrine ; Belongs to the class of sympathomimetics used as mydriatics and cycloplegics.
R01BA03 - phenylephrine ; Belongs to the class of systemic sympathomimetic preparations used as nasal decongestants.
R01AA04 - phenylephrine ; Belongs to the class of topical sympathomimetic agents used as nasal decongestants.