Carbinoxamine Maleate

Carbinoxamine maleate is a histamine-H₁ receptor blocking agent.

Each tablet contains 4 mg carbinoxamine maleate.

Inactive ingredients: anhydrous lactose, magnesium stearate, microcrystalline cellulose, and sodium starch glycolate.

Each 5 mL (teaspoonful) of oral solution contains 4 mg carbinoxamine maleate.

Inactive ingredients: artificial banana bubble gum flavor, citric acid (anhydrous), glycerin, purified water, sodium benzoate and sorbitol solution.

Carbinoxamine maleate is freely soluble in water.

Its structure is:

2-[(4-chlorophenyl)-2-pyridinylmethoxy]-N, N-dimethylethanamine (Z)-2-butenedioate (1:1)

Carbinoxamine maleate is an antihistamine with anticholinergic (drying) and sedative properties. Antihistamines appear to compete with histamine for receptor sites on effector cells.

The pharmacological effects of carbinoxamine maleate after oral absorption have been shown to last approximately 4 hours.

Interactions of carbinoxamine maleate with food or with other drugs and the possibility of cardiac conduction effects on the QT interval have not been studied.

Carbinoxamine maleate is effective for the symptomatic treatment of:

Seasonal and perennial allergic rhinitis.

Vasomotor rhinitis.

Allergic conjunctivitis due to inhalant allergens and foods.

Mild, uncomplicated allergic skin manifestations of urticaria and angioedema.

Dermatographism.

As therapy for anaphylactic reactions adjunctive to epinephrine and other standard measures after the acute manifestations have been controlled.

Amelioration of the severity of allergic reactions to blood or plasma.

Carbinoxamine maleate is contraindicated in children younger than 2 years of age.

Carbinoxamine maleate is contraindicated in nursing mothers.

Carbinoxamine maleate is contraindicated in patients who are hypersensitive to the drug or on monoamine oxidase inhibitor therapy. (See Drug Interactions section.)

Deaths have been reported in children less than 2 years of age who were taking antihistamines, including carbinoxamine-containing drug products, therefore, carbinoxamine maleate is contraindicated in children younger than 2 years of age (see CONTRAINDICATIONS).

Antihistamines should be used with considerable caution in patients with: narrow angle glaucoma, stenosing peptic ulcer, symptomatic prostatic hypertrophy, bladder neck obstruction, pyloroduodenal obstruction.

The most frequent adverse reactions are underlined:

Body as a Whole: Urticaria, drug rash, anaphylactic shock, photosensitivity, excessive perspiration, chills, dryness of mouth, nose and throat.

Cardiovascular: Hypotension, headache, palpitations, tachycardia, extrasystoles.

Hematologic: Hemolytic anemia, thrombocytopenia, agranulocytosis.

Central Nervous System:  Sedation, sleepiness, dizziness, disturbed coordination, fatigue, confusion, restlessness, excitation, nervousness, tremor, irritability, insomnia, euphoria, paresthesia, blurred vision, diplopia, vertigo, tinnitus, acute labyrinthitis, hysteria, neuritis, convulsions.

Gastrointestinal: Epigastric distress, anorexia, nausea, vomiting, diarrhea, constipation.

Urogenital: Urinary frequency, difficult urination, urinary retention, early menses.

Respiratory:  Thickening of bronchial secretions, tightness of chest and wheezing, nasal stuffiness.

Manifestations: Antihistamine overdosage reactions may vary from central nervous system depression to stimulation. Stimulation is particularly likely in children. Atropine-like signs and symptoms – dry mouth; fixed, dilated pupils; flushing; and gastrointestinal symptoms may also occur. Especially in infants and children, antihistamine overdosage may cause hallucinations, convulsions, or death.

The oral LD₅₀ of carbinoxamine maleate in guinea pigs is 411 mg/kg.

Treatment: The treatment of overdosage with carbinoxamine maleate is essentially symptomatic and supportive. Vital signs (including respiration, pulse, blood pressure, and temperature) and EKG should be monitored. Induction of vomiting is not recommended. Activated charcoal should be given and gastric lavage should be considered after ingestion of a potentially life-threatening amount of drug.

In the presence of severe anticholinergic effects, physostigmine may be useful. Vasopressors may be used to treat hypotension.

Carbinoxamine maleate is contraindicated in children younger than 2 years of age (see CONTRAINDICATIONS).

Carbinoxamine maleate should be taken on an empty stomach with water.

DOSAGE SHOULD BE INDIVIDUALIZED ACCORDING TO THE NEEDS AND THE RESPONSE OF THE PATIENT.

Carbinoxamine maleate dosage should be based on the severity of the condition and the response of the patient. The drug is well tolerated in adult doses as high as 24 mg daily, in divided doses, over prolonged periods. On the other hand, some patients respond to as little as 4 mg daily.

Clinical experience suggests the following dosage schedules:

TABLETS

Usual Adult Dosage:

1 or 2 tablets (4 to 8 mg) 3 to 4 times daily.

Usual Child’s Dosage:

Six to eleven years – 1/2 to 1 tablet (2 to 4 mg) 3 to 4 times daily.

ORAL SOLUTION

Usual Adult Dosage:

1 or 2 teaspoonfuls (4 to 8 mg) 3 to 4 times daily.

Usual Child’s Dosage:

(approximately 0.2 to 0.4 mg/kg/day, divided into 3 to 4 doses):

Six to eleven years – 1/2 to 1 teaspoonful (2 to 4 mg) 3 to 4 times daily.

Dosing for children 2 to 5 years of age should be based on weight whenever possible. The usual dosage for children 2 to 5 years of age is approximately 0.2 to 0.4 mg/kg/day, divided into 3 to 4 daily doses. In general, this corresponds to a dose of 1/4 to 1/2 teaspoonful (1 to 2 mg) 3 to 4 times daily.

Carbinoxamine Maleate Tablets USP, 4 mg are supplied as white, round tablets scored and debossed “B” bisected “P” on one side and “605” on the other side, and supplied in bottles of 100 tablets, NDC 64376-605-01.

Carbinoxamine Maleate Oral Solution, 4 mg/5 mL is supplied as clear, colorless liquid with a banana bubble gum flavor, and is supplied in 4 oz bottles NDC 64376-612-40 and 16 oz bottles NDC 64376-612-16.