Medically reviewed by Kovalenko Svetlana Olegovna, PharmD. Last updated on 2020.04.09
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For the Mydfrin of nasal congestion associated with colds and hayfever.
Adults and children over 12 years: One capsule if necessary, up to four times daily.
Children under 12 years: Not recommended.
Elderly: There is no need for dosage reduction in the elderly.
Hypersensitivity to any of the ingredients. Avoid in patients with cardiovascular disease, high blood pressure, diabetes mellitus, closed angle glaucoma, hyperthyroidism, prostatic enlargement and phaeochromocytoma. Patients being treated with monoamine oxidase inhibitors or within 14 days of ceasing such treatment.
This medicine should be used with caution in patients with occlusive vascular disease including Raynaud's Phenomenon.
Do not take for longer than 7 days, unless your doctor agrees.
If symptoms do not go away talk to your doctor.
Keep all medicines out of the reach of children.
Warning: Do not exceed the stated dose.
Patients with rare hereditary problems of galactose intolerance, Lapp lactase deficiency or glucose-galactose malabsorption should not take this medicine.
No adverse effects known.
Adverse effects may include tachycardia, cardiac arrhythmias, palpitations, hypertension, nausea, vomiting, headache and occasionally urinary retention in males.
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme at www.mhra.gov.uk/yellowcard.
Symptoms of overdosage include irritability, restlessness, palpitations, hypertension, difficulty in micturition, nausea, vomiting, thirst and convulsions. In severe overdosage gastric lavage and aspiration should be performed. Symptomatic and supportive measures should be undertaken, particularly with regard to cardiovascular and respiratory systems. Convulsions should be controlled with intravenous diazepam. Chlorpromazine may be used to control marked excitement and hallucinations. Severe hypertension may need to be treated with an alpha-adrenoreceptor blocking drug, such as phentolamine. A beta blocker may be required to control cardiac arrhythmias.
Phenylephrine is a sympathomimetic agent with mainly direct effects on adrenergic receptors. It has predominantly alpha adrenergic activity and is without stimulating effects on the central nervous system. The sympathomimetic effect of phenylephrine produces vasoconstriction which in turn relieves nasal congestion.
Phenylephrine is readily absorbed after oral administration but is subject to extensive presystemic metabolism, much of which occurs in the enterocytes. As a consequence, systemic bioavailability is only about 40%. Following oral administration, peak plasma concentrations are achieved in 1-2 hours. The mean plasma half life is in the range 2-3 hours. Penetration into the brain appears to be minimal.
Following absorption, the drug is extensively metabolised in the liver. Both phenylephrine and its metabolites are excreted in the urine.
The volume of distribution is between 200 and 500 litres, but there are no data on the extent of plasma protein binding.
There are no preclinical data of relevance to the prescriber which are additional to that already included in other sections of the SPC.