Storage, Stability, CompatibilityTablets should be stored in well-closed, light-resistant packaging at room temperature. No information on the storage, stability, or compatibility was found regarding the injectable product.
Pharmacology - DOXYLAMINE SUCCINATELike other antihistamines, doxylamine competitively inhibits histamine at H1receptors. It also has substantial sedative and anticholinergic effects.
Uses, IndicationsThis drug is recommended (by the manufacturer) "for use in conditions inwhich antihistaminic therapy may be expected to alleviate some signs of disease in dogs, cats, andhorses."
Pharmacokinetics - DOXYLAMINE SUCCINATEPharmacokinetic parameters are apparently unavailable for domestic animals.
Doxylamine has a serum half-life of approximately 10 hours in human adults.
Contraindications/Precautions - The manufacturer recommends that the injectable productshould not be administered by the IV route in dogs or cats, and that IM and SQ injection sites bedivided. Inject slowly IV in horses. Do not use in horses intended for food purposes.
Doxylamine is also contraindicated in patients who are hypersensitive to it or other antihistaminesin its class. Because of their anticholinergic activity, antihistamines should be used with caution inpatients with angle closure glaucoma, prostatic hypertrophy, pyloroduodenal or bladder neckobstruction, and COPD if mucosal secretions are a problem. Additionally, they should be used withcaution in patients with hyperthyroidism, cardiovascular disease or hypertension.
Adverse Effects, WarningsThe manufacturer lists CNS depression, incoordination and GI disturbances as adverse effects at therapeutic dosages.
Overdosage - The manufacturer includes CNS stimulation (excitement, seizures) and ataxia assymptoms associated with overdosage. Treatment should be supportive, as outlined in the previousantihistamine monographs.
Drug InteractionsPotential drug interactions for doxylamine include, increased sedation ifdoxylamine is combined with other CNS depressant drugs.
Antihistamines may partially counteract the anticoagulation effects of heparin or warfarin.
Doxylamine may enhance the effects of epinephrine.
Laboratory Interactions - Antihistamines can decrease the wheal and flare response to antigenskin testing. In humans, it is suggested that antihistamines be discontinued at least 4 days beforetesting.