Gentex LA

RX only

DESCRIPTION:
Decongestant and Expectorant tablets for oral administration.
Each tablet contains:
Guaifenesin . . . . . 650 mg
Phenylephrine
Hydrochloride . . . 23.75 mg
Guaifenesin is an expectorant.
Chemically, it is 1,2-
Propanediol, 3-(2-methoxyphenoxy)-,(±)-.

Phenylephrine hydrochloride is an orally effective nasal decongestant. Chemically it is Benzenemethanol, 3-hydroxy-
-[(methylamino) methyl]-, hydrochloride (R)-. Inactive ingredients include calcium phosphate, magnesium stearate, methylcellulose, povidone, Sterotex (hydrogenated vegetable oil).

CLINICAL PHARMACOLOGY
Phenylephrine hydrochloride is a sympathomimetic amine which acts predominantly by a direct action on alpha (
) adrenergic receptors. In therapeutic doses, the drug has no significant stimulant effect on the beta () drenergic receptors of the heart. Clinically, Phenylephrine shrinks swollen mucous membranes, reduces tissue hyperemia, edema, and nasal congestion; and increases nasal airway patency. In therapeutic doses the drug causes little, if any, central nervous system (CNS) stimulation. Guaifenesin is an expectorant which increases respiratory tract fluid secretions and helps to loosen phlegm and bronchial secretions. By reducing the viscosity of
secretions, guaifenesin increases the efficiency of the cough reflex and of ciliary action in removing accumulated secretions from the trachea and bronchi. Guaifenesin is readily absorbed from the gastrointestinal tract and is
rapidly metabolized and excreted in the urine. Guaifenesin has a plasma half-life of one hour. The major urinary metabolite is -(2-methoxyphenoxy) lactic acid.

INDICATIONS AND USAGE
Gentex LA is indicated for temporarily relieving symptoms of upper respiratory tract disorders such as sinusitis, asomotor rhinitis and hay fever; as well as for the temporary relief of coughs associated with respiratory tract nfections and related conditions such as sinusitis, pharyngitis, bronchitis, and asthma, when these conditions are omplicated by tenacious mucus and/or mucus plugs and congestion. This product is effective in a productive as ell as a non-productive cough, but is of particular value in a dry, non-productive cough which tends to injure the mucous membrane of the air passages..

CONTRAINDICATIONS
Gentex LA 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. Patients known to be hypersensitive to other sympathomimetic amines may exhibit cross sensitivity
with phenylephrine. Phenylephrine is contraindicated in patients with hypertension or ventricular tachycardia and should be employed only with extreme caution in elderly patients or in patients with hyperthyroidism, bradycardia,
partial heart block, myocardial disease, or severe arteriosclerosis. Phenylephrine is contraindicated in patients on
monoamine oxidase inhibitor (MAOI) therapy and for 14 days after stopping MAOI therapy (see “Drug Interactions” section).

WARNINGS
Sympathomimetic amines should be used judiciously and sparingly in patients with hypertension, diabetes mellitus, ischemic heart disease, increased intraocular pressure, hyperthyroidism or prostatic hypertrophy. Sympathomimetics may produce central nervous system stimulation with convulsions or cardiovascular collapse with accompanying hypotension.
DO NOT EXCEED RECOMMENDED DOSAGE.
Hypertensive crises can occur with concurrent use of phenylephrine and MAO inhibitors (and for 14 days after stopping MAOI therapy), indomethacin, or with betablockers and methyldopa. If a hypertensive crisis occurs,
these drugs should be discontinued immediately and therapy to lower blood pressure should be instituted. Fever
should be managed by means of external cooling. Before prescribing medication to suppress or modify a cough, its important that the underlying cause of the cough is identified, that modification of the cough does not increase the risk of clinical or physiological complications, and that appropriate therapy for the primary disease is instituted.

PRECAUTIONS
Information for Patients: Patient consultation should include the following information regarding proper use of this medication:
• Do not take more medication than the amount recommended.
• Take medication with food, water, or milk to minimize gastric irritation.
• Do not crush or chew tablets.
• Do not take monoamine oxidase inhibitors while taking this medication.
• If a dose is missed, the medication should be taken as soon as possible unless it is almost time for the next dose; not doubling doses.
• This medication should be stored in a tight, light-resistant container at temperatures between 59-86°F (15°-30°C).
• Keep all medications out of the reach of children. In case of accidental overdose, seek professional assistance
or contact a poison control center immediately.

DRUG INTERACTIONS
Beta adrenergic blockers and MAO inhibitors may potentiate the pressor effect of phenylephrine. Concurrent use of digitalis glycosides may increase the possibility of cardiac arrhythmias. Sympathomimetics may reduce the hypotensive effects of guanethidine, mecamylamine, methyldopa, reserpine and veratrum alkaloids. Concurrent
use of tricyclic antidepressants may antagonize the effects of phenylephrine. Use of other vasopressor drugs during halothane anesthia may cause serious cardiac arrhythmias.

DRUG/LABORATORY TEST INTERACTIONS
Interactions: Guaifenesin may increase renal clearance for urate and thereby lower serum uric acid levels. Guaifenesin may produce an increase in urinary 5-hydroxyindoleacetic 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 the drug should be discontinued 48 hours prior to the collection of urine specimens for such tests.

Carcinogenesis, Mutagenesis, Impairment of Fertility: No data are available on the long-term potential of Carcinogenesis, mutagenesis or impairment of fertility in animals or humans.

Pregnancy: Pregnancy Category C. Animal reproduction studies have not been conducted with this drug. It is also not known whether this drug can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. This drug should be given to a pregnant woman only if clearly needed.

Nursing Mothers: Use of this product by nursing mothers is not recommended because of the higher than usual risk for infants from sympathomimetic amines.

Pediatric Use: Safety and effectiveness of Gentex LA in children below the age of six have not been established.
Demonstrate safe use of a short-acting sympathomimetic amine before use of a sustained-action formulation in pediatric patients Appropriate studies on the relationship of age to the effects of guaifenesin have not been performed in the pediatric population. However no pediatric-specific problems have been documented to date.

Geriatric Use: Geriatric patients are more likely to experience adverse reactions to sympathomimetics. Overdosage of sympathomimetics in this age group may cause hallucinations, convulsions, CNS depression, and death. Demonstrate safe use of a short-acting sympathomimetic amine before use of a sustained-action formulation in geriatric patients.

ADVERSE REACTIONS
Hyperreactive individuals may display ephedrine-like reactions such as tachycardia, palpitations, headache,
dizziness or nausea. Sympathomimetics have been associated with certain untoward reactions including fear, anxiety, nervousness, restlessness, tremor, weakness, pallor, respiratory difficulty, dysuria, insomnia, hallucinations, convulsions, CNS depression, arrhythmias, and cardiovascular collapse with hypotension. No serious side effects from guaifenesin have been reported.

OVERDOSAGE
Gentex LA is comprised of pharmacologically different components (phenylephrine and guaifenesin). Therefore, it is difficult to predict the exact manifestation of symptoms in a given individual. A description of symptoms which are likely to appear after ingestion of an excess of the individual components follows: Overdosage with sympathomimetic amines can cause cardiac arrhythmias, cerebral hemorrhage and pulmonary edema. It can also cause palpitation, tremor, dizziness, vomiting, fear, labored breathing, headache, dryness of mouth, pallor, weakness, panic, anxiety, confusion, hallucinations, and delirium. 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 gm/kg, produced no signs of toxicity. Treatment of acute overdosage would probably be based upon treating the patient for the symptoms of overdosage of Phenylephrine as follows: The treatment of overdosage
should provide symptomatic and supportive care. If the amount ingested is considered dangerous or excessive, induce vomiting with ipecac syrup unless the patient is convulsing, comatose, or has lost the gag reflex, in which
case perform gastric lavage using a large-bore tube. If indicated, follow with activated charcoal and a saline cathartic.

DOSAGE AND ADMINISTRATION
Gentex LA tablets: Adults and children over 12 years of age: One tablet every 12 hours, not to exceed 2 tablets in 24 hours.

Children 6 to 12 years: One-half tablet every 12 hours, not to exceed 1 tablet in 24 hours. This product is not recommended for use in children under 6 years of age.

Do not crush or chew tablets.

HOW SUPPLIED
Gentex LA tablets are supplied as white capsule shaped tablets debossed "GENTEX LA" on one side, scored on the opposite. Bottles of 100 tablets, NDC 15014-002-01.

KEEP THIS AND ALL MEDICATION OUT OF THE REACH OF CHILDREN. IN CASE OF ACCIDENTAL OVERDOSE, SEEK PROFESSIONAL ASSISTANCE OR CONTACT A POISON CONTROL CENTER IMMEDIATELY.

Dispense in tight, light-resistant containers as defined in the USP/NF. Store at controlled room temperature
59°-86°F (15°- 30°C).

Manufactured for:
Gentex Pharma
Madison, MS 39110

500276 Iss. 10/2005