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Doxylamine Succinate

Pronunciation

Class: First Generation Antihistamines
ATC Class: R06AA09
VA Class: AH102
CAS Number: 562-10-7
Brands: Good Sense Sleep Aid, Unisom

Introduction

First generation antihistamine; an ethanolamine derivative.103 a b

Uses for Doxylamine Succinate

Insomnia

Self-medication for short-term management of insomnia,a particularly in individuals who have difficulty falling asleep.102

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Safety and efficacy not fully established; however, FDA states that, pending further accumulation of data, doxylamine-containing nighttime sleep aids that have been approved for this use may continue to be marketed in the US.

Allergic Rhinitis

Temporary relief of rhinorrhea, sneezing, lacrimation, itching eyes, or oronasopharyngeal itching associated with allergic rhinitis (e.g., hay fever) or other upper respiratory allergies.101

Doxylamine Succinate Dosage and Administration

Administration

Oral Administration

Administer orally as tablets.102 a

Dosage

Available as doxylamine succinate; dosage expressed in terms of the salt.102

Individualize dosage according to patient’s response and tolerance.b

Pediatric Patients

Insomnia
Oral

Self-medication in children ≥12 years of age: 25 mg 30 minutes before retiring or as directed by a clinician.102

Allergic Rhinitis

Children 2 to <6 years of age: 1.9–3.125 mg every 4–6 hours, not to exceed 18.75 mg in 24 hours.

Children 6 to <12 years of age: For self-medication, 3.75–6.25 mg every 4–6 hours, not to exceed 37.5 mg in 24 hours. Alternatively, under the direction of a clinician, up to 12.5 mg every 4–6 hours, or 2 mg/kg or 60 mg/m2 daily in divided doses, not to exceed 75 mg daily.

Children ≥12 years of age: For self-medication, 7.5–12.5 mg every 4–6 hours, not to exceed 75 mg in 24 hours. Alternatively, under the direction of a clinician, up to 25 mg every 4–6 hours, or 2 mg/kg or 60 mg/m2 daily in divided doses, not to exceed 150 mg daily.

Adults

Insomnia
Oral

Self-medication: 25 mg 30 minutes before retiring or as directed by a clinician.102

Allergic Rhinitis
Oral

Self-medication: 7.5–12.5 mg every 4–6 hours, not to exceed 75 mg in 24 hours. Alternatively, under the direction of a clinician, up to 25 mg every 4–6 hours, or 2 mg/kg or 60 mg/m2 daily in divided doses, not to exceed 150 mg daily.

Prescribing Limits

Pediatric Patients

Insomnia
Oral

Self-medication in children ≥12 years of age: Maximum 2 weeks.102

Allergic Rhinitis
Oral

Children 2 to <6 years of age: Maximum 18.75 mg in 24 hours.

Children 6 to <12 years of age: For self-medication, maximum 37.5 mg in 24 hours. Under the direction of a clinician, maximum 75 mg daily.

Children ≥12 years of age: For self-medication, maximum 75 mg in 24 hours. Under the direction of a clinician, maximum 150 mg daily.

Adults

Insomnia
Oral

Self-medication: Maximum 2 weeks.102

Allergic Rhinitis
Oral

For self-medication, maximum 75 mg in 24 hours. Under the direction of a clinician, maximum 150 mg daily.

Cautions for Doxylamine Succinate

Warnings/Precautions

Warnings

Concomitant Diseases

Because of possible anticholinergic effects (e.g., dryness of mouth, nose, and throat; dysuria; urinary retention),b patients with glaucoma, respiratory conditions (e.g., emphysema, chronic bronchitis), or difficulty urinating due to prostatic hypertrophy should consult a clinician before initiating therapy with doxylamine.101 102

Use with caution, if at all, in patients with angle-closure glaucoma, prostatic hypertrophy, stenosing peptic ulcer, pyloroduodenal obstruction, or bladder neck obstruction.b

Use not recommended, unless under the direction of a clinician, in patients who have a breathing problem (e.g., emphysema, chronic bronchitis). Use generally not recommended in asthmatics who previously experienced a serious antihistamine-induced adverse bronchopulmonary effect.

CNS Effects

Risk of marked drowsiness.101 Caution when driving a motor vehicle or operating machinery.101 (See CNS Depressants under Interactions and also see Advice to Patients.)

Possible excitability (especially in children).101 b (See Pediatric Use under Cautions.)

General Precautions

Duration of Therapy

When used for insomnia, discontinue therapy and consult a clinician if insomnia persists for >2 weeks.102

Specific Populations

Pregnancy

Category A.103

Women considering self-medication with doxylamine during pregnancy should consult a health professional for advice regarding the relative risks and benefits of such therapy.101

Lactation

Expected to be distributed into milk.103 Discontinue nursing or the drug.

Pediatric Use

Use not recommended in premature or full-term neonates.

Possible paradoxical excitement (e.g., restlessness, insomnia, tremors, euphoria, nervousness, delirium, palpitation, seizures).101 b

Safety and efficacy of doxylamine as a nighttime sleep aid in children <12 years of age not established.102 Consider risk of possible CNS stimulation when used as nighttime sleep aids.

Use as an antihistamine only under the direction of a clinician in children 2 to <6 years of age; use in children <2 years of age not recommended.

Risk of overdosage and toxicity (including death) in children <2 years of age receiving OTC preparations containing antihistamines, cough suppressants, expectorants, and nasal decongestants alone or in combination for relief of symptoms of upper respiratory tract infection. Limited evidence of efficacy for these preparations in this age group; appropriate dosages not established. Therefore, FDA recommended not to use such preparations in children <2 years of age; safety and efficacy in older children currently under evaluation. Because children 2–3 years of age also are at increased risk of overdosage and toxicity, some manufacturers of oral nonprescription cough and cold preparations recently agreed to voluntarily revise the product labeling to state that such preparations should not be used in children <4 years of age. During the transition period, some preparations on pharmacy shelves will have the new recommendation (“do not use in children <4 years of age”), while others will have the previous recommendation (“do not use in children <2 years of age”). FDA recommends that parents and caregivers adhere to dosage instructions and warnings on the product labeling that accompanies the preparation and consult a clinician about any concerns. Clinicians should ask caregivers about use of OTC cough/cold preparations to avoid overdosage.

Geriatric Use

Possible increased risk of dizziness, sedation, and hypotension.b

Common Adverse Effects

Drowsiness.101

Interactions for Doxylamine Succinate

Specific Drugs and Laboratory Tests

Drug or Laboratory Test

Interaction

Comments

CNS depressants (e.g., alcohol, hypnotics, sedatives, tranquilizers)

Possible additive CNS depression101 b

Avoid alcohol101 102 104

MAO inhibitors

MAO inhibitors prolong and intensify anticholinergic effects of antihistaminesb

Test, antigen or histamine

Inhalation-challenge testing with histamine or antigen: Possible suppression of test response

Antigen skin testing: Possible suppression of wheal and flare reactions

Doxylamine Succinate Pharmacokinetics

Absorption

Bioavailability

Peak plasma concentrations occur within 2–3 hours after oral administration.

Onset

Sedative effects occur approximately 30 minutes after oral administration.104

Elimination

Half-life

Approximately 10 hours.

Stability

Storage

Oral

Tablets

Well-closed, light-resistant containers at <40°C, preferably at 15–30°C.102 a

Actions

  • Blocks H1-receptor sites and prevents the action of histamine on the cell.b

  • Suppresses flare and pruritus that accompany the endogenous release of histamine.b

  • Exhibits some activities common to anticholinergics, ganglionic and adrenergic blocking agents, local anesthetics, and antispasmodics.b

  • Antihistamines do not block the stimulating effect of histamine on gastric acid secretion, which is mediated by the H2-receptors of the parietal cells.b

Advice to Patients

  • Risk of marked drowsiness; avoid alcohol and use caution when driving or operating machinery.101 102 104

  • When used for insomnia, consult a clinician if sleeplessness persists continuously for >2 weeks.102

  • Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as any concomitant illnesses.101 102 Importance of patients already receiving another CNS depressant (e.g., sedatives, tranquilizers) not undertaking self-medication without first consulting a clinician.101 102

  • Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed;101 102 women considering self-medication with doxylamine during pregnancy should consult a clinician regarding the relative risks and benefits of such therapy.102 104

  • Importance of informing patients of other important precautionary information.101 102 (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Many prescription cough, cold, and allergy preparations commercially available in the US have not been approved by FDA.500 Because of the potentially serious health risks associated with unapproved preparations, FDA announced on March 3, 2011, that it would take enforcement action (e.g., seizure, injunction, other judicial or administrative proceeding) against any currently marketed and listed unapproved cough, cold, and allergy preparation manufactured on or after June 1, 2011 or shipped on or after August 30, 2011.500 For additional information and for a complete list of unapproved cough, cold, and allergy preparations affected by this FDA notice, see FDA website ().

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

Doxylamine Succinate

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Oral

Tablets

25 mg*

Doxylamine Succinate Tablets

Good Sense Sleep Aid Tablets

Perrigo

Unisom SleepTabs (scored)

Chattem

Doxylamine succinate is also commercially available in combination with antitussives and decongestants.

AHFS DI Essentials. © Copyright, 2004-2014, Selected Revisions January 9, 2012. American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland 20814.

References

101. Zyber Pharmaceuticals, Inc. Aldex AN (doxylamine succinate) oral suspension prescribing information. Gonzales, LA; undated.

102. Chattem. Unisom SleepTabs (doxylamine succinate) tablets product information. Chattanooga, TN. From Chattem website. Accessed 2008 Jan 22.

103. Doxylamine. In: Briggs GG, Freeman RK, Yaffe SJ. Drugs in pregnancy and lactation. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005:519-24.

104. Chattem. Unisom SleepTabs (doxylamine succinate) frequently asked questions. Chattanooga, TN. From Chattem website. Accessed 2008 Jan 22.

500. Food and Drug Administration. Drugs for human use; unapproved and misbranded oral drugs labeled for prescription use and offered for relief of symptoms of cold, cough, or allergy, enforcement action dates. Notice. [Docket No. FDA-2011-N-0100] Fed Regist. 2011; 76:11794-8.

a. AHFS Drug Information 2008. McEvoy GK, ed. Doxylamine Succinate. Bethesda, MD: American Society of Health-System Pharmacists; 2008:20-1.

b. AHFS Drug Information 2008. McEvoy GK, ed. Antihistamines General Statement. Bethesda, MD: American Society of Health-System Pharmacists; 2008:1-8.

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