Silafed

Uses

This combination medication is used to temporarily relieve symptoms caused by the common cold, flu, allergies, or other breathing illnesses (such as sinusitis, bronchitis). Pseudoephedrine (antihistamines) help relieve watery eyes, itchy eyes/nose/throat, runny nose, and sneezing. Triprolidine (decongestants) help to relieve stuffy nose and ear congestion symptoms

Silafed is also used to associated treatment for these conditions: Allergic Rhinitis (AR), Allergies, Common Cold, Common Cold Associated With Cough, Common Cold/Flu, Cough, Cough caused by Common Cold, Eye allergy, Fever, Flu caused by Influenza, Headache, Irritative cough, Nasal Allergies, Nasal Congestion, Nasal Congestion caused by Common Cold, Pain, Perennial Allergy, Priapism, Respiratory Allergy, Rhinorrhoea, Seasonal Allergic Rhinitis, Seasonal Allergies, Sinus Congestion, Sinusitis, Sneezing, Sore Throat, Symptoms of Acute Bronchitis Accompanied by Coughing, Throat irritation, Upper Respiratory Tract Infection, Upper respiratory tract congestion, Upper respiratory tract signs and symptoms, Dry cough, Minor aches and pains, Sinus pain, Watery itchy eyes, Airway secretion clearance therapyNasal Congestion, Perennial Allergic Rhinitis (PAR), Seasonal Allergic Conjunctivitis, Seasonal Allergic Rhinitis, Upper respiratory tract signs and symptoms, Vasomotor Rhinitis, Mild Angioedema, Mild urticaria, Upper respiratory discomfort

How Silafed works

Pseudoephedrine acts mainly as an agonist of alpha adrenergic receptors and less strongly as an agonist of beta adrenergic receptors.[A10896] This agonism of adrenergic receptors produces vasoconstriction which is used as a decongestant and as a treatment of priapism. Pseudoephedrine is also an inhibitor of norepinephrine, dopamine, and serotonin transporters.

The sympathomimetic effects of pseudoephedrine include an increase in mean arterial pressure, heart rate, and chronotropic response of the right atria. Pseudoephedrine is also a partial agonist of the anococcygeal muscle. Pseudoephedrine also inhibits NF-kappa-B, NFAT, and AP-1.

Triprolidine binds to the histamine H1 receptor. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine.

Dosage

Silafed dosage

Adult: 1 tablet 4-6 hrly, up to 4 times a day.

Child >12 year: 1 tablet 4-6 hrly, up to 4 times a day.

Side Effects

Drowsiness, dizziness, dry mouth/nose/throat, headache, upset stomach, constipation, or trouble sleeping may occur.

Toxicity

The oral LD₅₀ of pseudoephedrine is 2206mg/kg in rats and 726mg/kg in mice.

Patients experiencing an overdose of pseudoephedrine may present with giddiness, headache, nausea, vomiting, sweating, thirst, tachycardia, precordial pain, palpitations, difficulty urinating, muscle weakness, muscle tension, anxiety, restlessness, insomnia, toxic psychosis, cardiac arrhythmias, circulatory collapse, convulsions, coma, and respiratory failure. Treat overdose with symptomatic and supportive treatment including removal of unabsorbed drug.

Symptoms of overdose include drowsiness, weakness, inco-ordination, difficulty with micturition, respiratory depression, hypotension, agitation, irritability, convulsions, hypertension, palpitation and tachycardia.

Precaution

Severe hepatic impairment. Moderate to severe renal impairment. DM, hyperthyroidism, increased intraocular pressure, prostatic hypertrophy, hypertension, heart disease. May affect ability to drive or operate machinery. Pregnancy and lactation.

Interaction

Increased BP with other sympathomimetic agents (e.g. decongestants, TCA, appetite suppressants). Reduced hypotensive effects of methyldopa, α- and β-adrenergic blockers. Increased side effects (e.g. somnolence, agitation) with atomoxetine.

Volume of Distribution

The apparent volume of distribution of pseudoephedrin is 2.6-3.3L/kg.

Elimination Route

A 240mg oral dose of pseudoephedrine reaches a C_max of 246.3±10.5ng/mL fed and 272.5±13.4ng/mL fasted, with a T_max of 6.60±1.38h fed and 11.87±0.72h fasted, with an AUC of 6862.0±334.1ng*h/mL fed and 7535.1±333.0ng*h/mL fasted.

Rapidly absorbed in the intestinal tract.

Half Life

The mean elimination half life of pseudoephedrine is 6.0h.

4 to 6 hours.

Clearance

A 60mg oral dose of pseudoephedrine has a clearance of 5.9±1.7mL/min/kg.

Elimination Route

55-75% of an oral dose is detected in the urine as unchanged pseudoephedrine.

Pregnancy & Breastfeeding use

Pregnancy Category- C. Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks

Contraindication

Concurrent use or within 2 wk of stopping MAOIs. Severe hypertension or coronary artery disease.

Acute Overdose

Symptoms: Drowsiness, lethargy, dizziness, ataxia, weakness, difficulty passing urine, dry skin, tachycardia, hypertension, high fever, hyperactivity, irritability, seizures and respiratory depression.

Management: Gastric lavage may be performed up to 3 hr after overdose. Treatment is supportive and symptomatic. Acid diuresis or dialysis may be helpful in pseudoephedrine elimination.

Storage Condition

Tablet: Do not store above 25° C.

Syrup: Do not store above 25° C. Diluted syrup can be stored up to 4 wk at 25° C.

Innovators Monograph

You find simplified version here Silafed