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Exefen (Pseudoephedrine Hydrochloride / Guaifenesin) - Drug Interactions, Contraindications, Overdosage, etc



Drug/Laboratory Test Interactions

Guaifenesin may increase renal clearance for urate and thereby lower serum uric acid levels. Guaifenesin may produce an increase in urinary 5-hydroxyindolacetic acid and may therefore interfere with the interpretation of this test for the diagnosis of carcinoid syndrome. It may also falsely elevate the VMA test for catechols. Administration of this product should be discontinued 48 hours prior to the collection of urine specimens for such tests.

Carcinogenesis, Mutagenesis, Impairment of Fertility

No long term or reproduction studies in animals have been performed with EXEFEN-IR Tablets to evaluate its carcinogenic, mutagenic and impairment of fertility potential.


Pregnancy Category C

Animal reproduction studies have not been conducted with EXEFEN-IR Tablets. It is not known whether EXEFEN-IR Tablets can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. EXEFEN-IR Tablets should be given to a pregnant woman only if clearly needed.


Overdosage with pseudoephedrine can cause excessive CNS stimulation resulting in excitement, nervousness, anxiety, tremor, restlessness, and insomnia. Other effects include tachycardia, hypertension, pallor, mydriasis, hyperglycemia and urinary retention. Severe overdosage may cause tachypnea or hyperpnea, hallucinations, convulsions or delirium, but in some individuals there may be CNS depression with somnolence, stupor or respiratory depression. Arrhythmias (including ventricular fibrillation) may lead to hypotension and circulatory collapse. Severe hypokalemia can occur, probably due to compartmental shift rather than depletion of potassium. No organ damage or significant metabolic derangement is associated with Pseudoephedrine overdosage.

The LD50 (single, oral dose) of Pseudoephedrine is 726 mg/kg in the mouse, 2206 mg/kg in the rat and 1177 mg/kg in the rabbit. The toxic and lethal concentrations in human biologic fluids are not known. Excretion rates increase with urine acidification and decrease with alkalinization. Few reports of toxicity due to pseudoephedrine have been published and no case of fatal overdosage is known.


The patient should be induced to vomit, even if emesis has occurred spontaneously; however, vomiting should not be induced in patients with impaired consciousness. Precautions against aspiration should be taken, especially in infants and children.

Ipecac syrup is the preferred method for inducing vomiting. The action of ipecac syrup is facilitated by physical activity and the administration of eight to twelve fluid ounces of water. If emesis does not occur in fifteen minutes, the dose of ipecac should be repeated. Following emesis, any drug remaining in the stomach may be absorbed by activated charcoal administered as a slurry with water.

If vomiting is unsuccessful or contraindicated, gastric lavage should be performed. Isotonic and one-half isotonic saline are the lavage solutions of choice. Saline cathartics, such as milk of magnesia, draw water into the bowel by osmosis and, therefore, may be valuable for their action of rapid dilution of bowel content.

Treatment of the signs and symptoms of overdosage is symptomatic and supportive. Vasopressors maybe used to treat hypotension. Short- acting barbiturates, diazepam or paraldehyde maybe administered to control seizures. Hyperpyrexia, especially in children, may require treatment with tepid water sponge baths or a hypothermic blanket. Apnea is treated with ventilatory support. Stimulants (analeptic agents) should not be used.


Overdosage with Guaifenesin is unlikely to produce toxic effects since its toxicity is low. Guaifenesin, when administered by stomach tube to test animals in doses up to 5 grams/kg, produced no signs of toxicity. In severe cases of overdosage, treatment should be aimed at reducing further absorption of the drug. Gastric emptying (Syrup of Ipecac) and/or lavage is recommended as soon as possible after ingestion.


EXEFEN-IR is contraindicated in patients with hypersensitivity to Guaifenesin or with hypersensitivity or idiosyncrasy to sympathomimetic amines which may be manifested by insomnia, dizziness, weakness, tremor or arrhythmias.

Sympathomimetic amines are contraindicated in patients with severe hypertension, severe coronary artery disease and in patients on monoamine oxidase (MAO) inhibitor therapy.

Nursing Mothers

Contraindicated because of the higher than usual risk for infants from sympathomimetic amines.

Newborn or Premature Infants

EXEFEN-IR Tablets should not be administered to premature or full-term infants.

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