AHFS Class:

• First Generation Antihistamines 4:04

Generic Name(s):

• Carbinoxamine Maleate

Associated Monographs

• Antihistamines General Statement

Carbinoxamine is an ethanolamine-derivative, first generation antihistamine.100,101

Carbinoxamine shares the actions and uses of other antihistamines.100 (See Uses in the Antihistamines General Statement 4:00.)

Regulations Governing Carbinoxamine-containing Preparations

Carbinoxamine maleate was initially introduced to the US market in the early 1950s under the Federal Food, Drug, and Cosmetic Act of 1938, which required that new drugs be proven safe for use.101 After 1962, when Congress amended the Act to require that new drugs be proven effective (as well as safe), carbinoxamine maleate was subject to the Drug Efficacy Study Implementation (DESI) review process and subsequently, in 1973, found to be effective for nasal allergies and other allergic conditions.101 To legally market carbinoxamine maleate preparations, McNeil Laboratories submitted new drug applications (NDAs) for carbinoxamine maleate oral solution and tablets; however, these NDAs were later withdrawn (in 1985 and 1994, respectively) at the request of the manufacturer because the preparations were no longer marketed.101 As of June 2006, only one manufacturer (Mikart) had approved abbreviated new drug applications (ANDAs) for carbinoxamine maleate tablets (4 mg) and oral solution (4 mg/5 mL).101

Although Mikart preparations were the only carbinoxamine-containing preparations with approved applications as of June 2006, numerous unapproved carbinoxamine-containing preparations (single-entity or fixed-combination preparations) remained on the US market.101,102,103,500 Many of these unapproved preparations contained inappropriate labeling that promoted unapproved uses (including management of congestion†, cough†, or the common cold†, and use in children younger than 2† years of age), which may pose serious health risks.101,102 Since 1983, there have been 21 reported deaths in children younger than 2 years of age receiving carbinoxamine-containing preparations.101,102 Although a causal relationship to carbinoxamine has not been established, some data indicate that infants and young children may be more susceptible to drug-related adverse effects, partly due to the normal immaturity of their metabolic pathways.101 Furthermore, parents or caregivers of infants or young children receiving carbinoxamine-containing preparations may have difficulty identifying potentially serious or life-threatening adverse events associated with the drug.101

Because of the potentially serious health risks associated with use of unapproved carbinoxamine-containing preparations, and because approved carbinoxamine maleate preparations were available on the US market (i.e., tablets and oral solution manufactured by Mikart), FDA announced on June 8, 2006 that it would take enforcement action (e.g., seizure, injunction, other judicial proceeding) against all firms attempting to manufacture carbinoxamine-containing preparations after September 7, 2006 without an approved application.101 Manufacturers who wished to continue marketing preparations containing carbinoxamine were required to submit an ANDA for such preparations.101 Following this announcement, several other manufacturers submitted ANDAs and received marketing approval for carbinoxamine maleate preparations.108

Administration

Carbinoxamine maleate is administered orally.100 Carbinoxamine maleate tablets and oral solution should be taken on an empty stomach with water.100

Dosage

Dosage of carbinoxamine maleate should be individualized according to the patient's response and tolerance.100 Some patients may respond to a dosage as low as 4 mg daily, although dosages as high as 24 mg daily are well tolerated.100

Nasal Allergies and Other Allergic Conditions

For the symptomatic treatment of nasal allergies and other allergic conditions, the usual adult dosage of carbinoxamine maleate is 4-8 mg 3-4 times daily.100

The usual dosage of carbinoxamine maleate for children 2 years of age and older is approximately 0.2-0.4 mg/kg daily.100 The manufacturer suggests that children older than 6 years of age may receive 4-6 mg 3 or 4 times daily (as tablets or oral solution); children 3-6 years of age may receive 2-4 mg 3 or 4 times daily (as an oral solution); and children 2-3 years of age may receive 2 mg 3 or 4 times daily (as an oral solution).100

Carbinoxamine shares the toxic potentials of other antihistamines, and the usual precautions of antihistamine therapy should be observed. (See Cautions in the Antihistamines General Statement 4:00.)

Pediatric Precautions

Carbinoxamine may diminish mental alertness in children.100 In young children, the drug may produce paradoxical excitation.100

Safety and efficacy of carbinoxamine have not been established in children younger than 2 years of age,101 and the manufacturer states that the drug is contraindicated in such children.100

Despite specific contraindications, carbinoxamine continued to be used in children younger than 2 years of age, in some cases with other prescription and/or nonprescription (over-the-counter, OTC) cough and cold preparations containing other agents (e.g., cough suppressants, expectorants, nasal decongestants).105 In a report published by the US Centers for Disease Control and Prevention (CDC), cough and cold preparations containing carbinoxamine, pseudoephedrine, acetaminophen, and/or dextromethorphan were determined by medical examiners or coroners to be the underlying cause of death in 3 infants 6 months of age or younger during 2005.105,106 The actual cause of death might have been overdosage of one drug, interaction of different drugs, an underlying medical condition, or a combination of drugs and underlying medical conditions.105 In addition, an estimated 1519 children younger than 2 years of age were treated in emergency departments in the US during 2004-2005 for adverse events, including overdoses, associated with cold and cough preparations.105 For additional information on precautions associated with the use of cough and cold preparations in pediatric patients, see Cautions: Pediatric Precautions in the Antihistamines General Statement 4:00.

Geriatric Precautions

Geriatric patients (60 years of age and older) may be particularly susceptible to dizziness, sedation, and hypotension.100 Confusion or oversedation also may occur.100 Geriatric patients should receive lower initial dosages of carbinoxamine maleate and should be monitored carefully.100

Mutagenicity and Carcinogenicity

Long-term studies to determine the mutagenic and carcinogenic potentials of carbinoxamine have not been performed to date.100

Pregnancy, Fertility, and Lactation

Pregnancy

It is not known whether carbinoxamine can cause fetal harm when administered to pregnant women.100 Carbinoxamine should be used during pregnancy only when clearly needed.100

Fertility

It is not known whether carbinoxamine affects fertility.100

Lactation

Because of the potential for serious adverse reactions to antihistamines in nursing infants, particularly premature or full-term neonates, use of carbinoxamine is contraindicated in nursing women.100

Chemistry and Stability

Chemistry

Carbinoxamine is an ethanolamine-derivative antihistamine.100,101 Carbinoxamine maleate occurs as a white, odorless, crystalline powder and has solubilities of greater than 1 g/mL in water and approximately 0.67 g/mL in alcohol at 25°C. The pK_a of the drug is 8.1.

Stability

Carbinoxamine maleate tablets and oral solution should be dispensed in tight, light-resistant containers with child-resistant closures, and stored at 15-30°C.100

Additional Information

For further information on chemistry, pharmacology, pharmacokinetics, uses, cautions, acute toxicity, drug interactions, laboratory test interferences, and dosage and administration of carbinoxamine, see the Antihistamines General Statement 4:00.

Please see the general statement for a list of references.