Note: Safety and efficacy for the use of cough and cold products in infants and young children is limited; the AAP warns against the use of these products for respiratory illnesses in infants and young children; the FDA does not recommend OTC use in infants and children <2 years of age due to the risk of serious and life-threatening adverse effects (including death) and recommends to use with caution in pediatric patients ≥2 years of age (Ref).
Allergic symptoms: Oral:
Immediate release:
Oral liquid (2 mg/5 mL):
Children 2 to <6 years: Limited data available: 1 mg every 4 to 6 hours; maximum daily dose: 6 mg/day (Ref)
Children 6 to <12 years: 2 mg every 4 to 6 hours; maximum daily dose: 12 mg/day.
Children ≥12 years and Adolescents: 4 mg every 4 to 6 hours; maximum daily dose: 24 mg/day.
Tablets:
Children 6 to <12 years: 2 mg every 4 to 6 hours; maximum daily dose: 12 mg/day.
Children ≥12 years and Adolescents: 4 mg every 4 to 6 hours; maximum daily dose: 24 mg/day.
Extended-release tablet: Children ≥12 years and Adolescents: 12 mg every 12 hours; maximum dose: 24 mg in 24 hours.
There are no dosage adjustments provided in manufacturer's labeling.
There are no dosage adjustments provided in manufacturer's labeling; however, chlorpheniramine is metabolized via the liver; therefore, a dose adjustment may be necessary.
(For additional information see "Chlorpheniramine: Drug information")
Motion sickness (off-label use): Immediate release: Oral: 4 to 12 mg administered 3 hours prior to initiating stimulus for motion sickness (Ref). Note: Avoid use if it is unsafe for patient to be sedated.
Upper respiratory tract conditions:
Note: Second-generation H1-antihistamines are generally preferred due to less sedating and anticholinergic effects. Avoid use in patients with high-risk occupations (eg, pilots, bus drivers) or who may be more prone to anticholinergic effects (eg, older adults) (Ref).
Immediate release: Oral: 4 mg every 4 to 6 hours; do not exceed 24 mg/24 hours.
Extended release: Oral: 12 mg every 12 hours; do not exceed 24 mg/24 hours.
Urticaria, new onset and chronic spontaneous (alternative agent) (off-label use):
Note: Second-generation H1-antihistamines are preferred due to less sedating and anticholinergic effects (Ref). May consider use in combination with a second-generation H1-antihistamine in patients in whom bedtime sedating effects may be beneficial; avoid use in patients with high-risk occupations (eg, pilots, bus drivers) or who may be more prone to anticholinergic effects (eg, older adults) (Ref). Dosing is based on manufacturer’s labeling for use in upper respiratory tract conditions.
Immediate release: Oral: 4 mg every 4 to 6 hours; do not exceed 24 mg/24 hours.
Extended release: Oral: 12 mg every 12 hours; do not exceed 24 mg/24 hours.
The renal dosing recommendations are based upon the best available evidence and clinical expertise. Senior Editorial Team: Bruce Mueller, PharmD, FCCP, FASN, FNKF; Jason A. Roberts, PhD, BPharm (Hons), B App Sc, FSHP, FISAC; Michael Heung, MD, MS.
Note: Limited information exists regarding the disposition of chlorpheniramine in patients with kidney impairment.
Altered kidney function:
eGFR >30 mL/minute/1.73 m2: No dosage adjustment necessary (Ref).
eGFR ≤30 mL/minute/1.73 m2: No initial dosage adjustment necessary; however, greatly prolonged half-lives in patients with severe kidney disease have been reported; use with caution (Ref).
Hemodialysis, intermittent (thrice weekly): Unlikely to be dialyzed (large Vd): Dose as for eGFR ≤30 mL/minute/1.73 m2 (Ref).
Peritoneal dialysis: Unlikely to be dialyzed (large Vd): Dose as for eGFR ≤30 mL/minute/1.73 m2 (Ref).
CRRT: Dose as for eGFR ≤30 mL/minute/1.73 m2 (Ref).
PIRRT (eg, sustained, low-efficiency diafiltration): Dose as for eGFR ≤30 mL/minute/1.73 m2 (Ref).
There are no dosage adjustments provided in the manufacturer's labeling; however, chlorpheniramine is metabolized via the liver; therefore, a dose adjustment may be necessary.
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.
>10%:
Central nervous system: Drowsiness (slight to moderate)
Respiratory: Thickening of bronchial secretions
1% to 10%:
Central nervous system: Dizziness, excitability, fatigue, headache, nervousness
Endocrine & metabolic: Weight gain
Gastrointestinal: Abdominal pain, diarrhea, increased appetite, nausea, xerostomia
Genitourinary: Urinary retention
Neuromuscular & skeletal: Arthralgia, weakness
Ophthalmic: Diplopia
Renal: Polyuria
Respiratory: Pharyngitis
OTC labeling: When used for self-medication, do not use to make a child sleep.
Concerns related to adverse effects:
• CNS depression: May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving).
Special populations:
• Pediatric: Antihistamines may cause excitation in young children.
Dosage form specific issues:
• Benzyl alcohol and derivatives: Some dosage forms may contain sodium benzoate/benzoic acid; benzoic acid (benzoate) is a metabolite of benzyl alcohol; large amounts of benzyl alcohol (≥99 mg/kg/day) have been associated with a potentially fatal toxicity (“gasping syndrome”) in neonates; the “gasping syndrome” consists of metabolic acidosis, respiratory distress, gasping respirations, CNS dysfunction (including convulsions, intracranial hemorrhage), hypotension, and cardiovascular collapse (AAP ["Inactive" 1997]; CDC 1982); some data suggests that benzoate displaces bilirubin from protein binding sites (Ahlfors 2001); avoid or use dosage forms containing benzyl alcohol derivative with caution in neonates. See manufacturer's labeling.
• Propylene glycol: Some dosage forms may contain propylene glycol; large amounts are potentially toxic and have been associated with hyperosmolality, lactic acidosis, seizures, and respiratory depression; use caution (AAP 1997; Zar 2007).
Other warnings/precautions:
• Self-medication (OTC use): When used for self-medication (OTC), notify health care provider prior to use if you have breathing problems (eg, chronic bronchitis, emphysema), glaucoma, difficultly in urination due to enlargement of the prostate gland, or are currently taking sedatives, tranquilizers.
Safety and efficacy for the use of cough and cold products in pediatric patients <4 years of age is limited; the AAP warns against the use of these products for respiratory illnesses in young children. Serious adverse effects including death have been reported. Many of these products contain multiple active ingredients, increasing the risk of accidental overdose when used with other products. The FDA does not recommend OTC uses for these products in pediatric patients <2 years of age and recommends to use with caution in pediatric patients ≥2 years of age. Health care providers are reminded to ask caregivers about the use of OTC cough and cold products in order to avoid exposure to multiple medications containing the same ingredient (AAP 2018; CDC 2007; FDA 2017; FDA 2018).
Some dosage forms may contain propylene glycol; in neonates large amounts of propylene glycol delivered orally, intravenously (eg, >3,000 mg/day), or topically have been associated with potentially fatal toxicities which can include metabolic acidosis, seizures, renal failure, and CNS depression; toxicities have also been reported in children and adults including hyperosmolality, lactic acidosis, seizures and respiratory depression; use caution (AAP 1997; Shehab 2009).
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Syrup, Oral, as maleate:
Chlor-Trimeton: 2 mg/5 mL (120 mL [DSC]) [contains alcohol, usp]
Ed Chlorped Jr: 2 mg/5 mL (473 mL) [alcohol free, sugar free; contains fd&c red #40 (allura red ac dye), methylparaben, propylene glycol, propylparaben; cherry flavor]
Tablet, Oral, as maleate:
Aller-Chlor: 4 mg [scored; contains quinoline (d&c yellow #10) aluminum lake]
Allergy: 4 mg [scored; contains corn starch, quinoline (d&c yellow #10) aluminum lake]
Allergy Relief: 4 mg [contains corn starch, quinoline (d&c yellow #10) aluminum lake]
Allergy Relief: 4 mg [scored; contains corn starch, quinoline (d&c yellow #10) aluminum lake]
Allergy Relief: 4 mg [DSC] [contains quinoline (d&c yellow #10) aluminum lake]
Allergy-Time: 4 mg [DSC] [contains quinoline (d&c yellow #10) aluminum lake]
Chlor-Trimeton: 4 mg [DSC] [scored]
Chlorphen: 4 mg [scored; contains corn starch, quinoline (d&c yellow #10) aluminum lake]
FT Allergy Relief: 4 mg [contains corn starch, quinoline (d&c yellow #10) aluminum lake]
GoodSense Allergy Relief: 4 mg [contains quinoline (d&c yellow #10) aluminum lake]
Pharbechlor: 4 mg
Generic: 4 mg
Tablet Extended Release, Oral, as maleate:
Chlor-Trimeton Allergy: 12 mg [contains fd&c blue #2 (indigo carm) aluminum lake, fd&c yellow #6(sunset yellow)alumin lake, quinoline (d&c yellow #10) aluminum lake]
Chlor-Trimeton Allergy: 12 mg [DSC] [contains fd&c yellow #6 (sunset yellow), fd&c yellow #6(sunset yellow)alumin lake]
Generic: 12 mg
Yes
Tablet, controlled release (Chlor-Trimeton Allergy Oral)
12 mg (per each): $0.46
Tablet, controlled release (Chlorpheniramine Maleate ER Oral)
12 mg (per each): $0.63
Tablets (Chlorpheniramine Maleate Oral)
4 mg (per each): $0.01
Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.
Oral: Administer liquid formulations with an accurate measuring device; do not use a household teaspoon (overdosage may occur). Extended-release oral forms are to be swallowed whole, not crushed or chewed.
Oral:
May be administered with food or water. Timed release oral forms are to be swallowed whole, not crushed or chewed. Administer liquid formulations with an accurate measuring device; do not use a household teaspoon (overdosage may occur). If used for motion sickness, administer 3 hours before stimulus.
Bariatric surgery: Capsule and tablet, extended release: Some institutions may have specific protocols that conflict with these recommendations; refer to institutional protocols as appropriate. Switch to IR formulation.
Store at room temperature.
Temporary relief of symptoms associated with hay fever and other respiratory allergies (eg, runny nose; itchy, watery eyes; sneezing; itching of nose or throat) (OTC products: Oral liquid: FDA approved in ages ≥6 years and adults); tablets [immediate release]: FDA approved in ages ≥6 years and adults; tablets [extended release: 12 hours]: FDA approved in ages ≥12 years and adults); Note: Approved ages and uses for products may vary; consult labeling for specific information.
Chlor-Trimeton may be confused with Chloromycetin
The Institute for Safe Medication Practices (ISMP) includes this medication among its list of drugs (pediatric liquid medications requiring measurement) which have a heightened risk of causing significant patient harm when used in error (High-Alert Medications in Community/Ambulatory Care Settings).
Beers Criteria: Chlorpheniramine, a first-generation antihistamine, is identified in the Beers Criteria as a potentially inappropriate medication to be avoided in patients 65 years and older (independent of diagnosis or condition) because of its potent anticholinergic properties resulting in increased risk of confusion, dry mouth, constipation, and other anticholinergic effects or toxicity; use should also be avoided because of reduced clearance with advanced age and tolerance associated with use as a hypnotic. Exposure to concurrent anticholinergic drugs also increases risk of falls, delirium, and dementia; consider total anticholinergic burden when conducting medication reviews (Beers Criteria [AGS 2023]).
Substrate of CYP2D6 (major), CYP3A4 (minor); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program
Acetylcholinesterase Inhibitors: May diminish the therapeutic effect of Agents with Clinically Relevant Anticholinergic Effects. Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Acetylcholinesterase Inhibitors. Risk C: Monitor therapy
Aclidinium: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid combination
Agents with Clinically Relevant Anticholinergic Effects: May enhance the adverse/toxic effect of other Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Ajmaline: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Risk C: Monitor therapy
Alcohol (Ethyl): CNS Depressants may enhance the CNS depressant effect of Alcohol (Ethyl). Risk C: Monitor therapy
Alizapride: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Amantadine: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Amezinium: Antihistamines may enhance the stimulatory effect of Amezinium. Risk C: Monitor therapy
Artemether and Lumefantrine: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Risk C: Monitor therapy
Azelastine (Nasal): May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Benperidol: Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Benperidol. Risk C: Monitor therapy
Benzylpenicilloyl Polylysine: Antihistamines may diminish the diagnostic effect of Benzylpenicilloyl Polylysine. Management: Suspend systemic H1 antagonists for benzylpenicilloyl-polylysine skin testing and delay testing until systemic antihistaminic effects have dissipated. A histamine skin test may be used to assess persistent antihistaminic effects. Risk D: Consider therapy modification
Betahistine: Antihistamines may diminish the therapeutic effect of Betahistine. Betahistine may diminish the therapeutic effect of Antihistamines. Risk C: Monitor therapy
Blonanserin: CNS Depressants may enhance the CNS depressant effect of Blonanserin. Management: Use caution if coadministering blonanserin and CNS depressants; dose reduction of the other CNS depressant may be required. Strong CNS depressants should not be coadministered with blonanserin. Risk D: Consider therapy modification
Botulinum Toxin-Containing Products: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Brexanolone: CNS Depressants may enhance the CNS depressant effect of Brexanolone. Risk C: Monitor therapy
Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Bromopride: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Bromperidol: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Buprenorphine: CNS Depressants may enhance the CNS depressant effect of Buprenorphine. Management: Consider reduced doses of other CNS depressants, and avoiding such drugs in patients at high risk of buprenorphine overuse/self-injection. Initiate buprenorphine at lower doses in patients already receiving CNS depressants. Risk D: Consider therapy modification
Cannabinoid-Containing Products: Agents with Clinically Relevant Anticholinergic Effects may enhance the tachycardic effect of Cannabinoid-Containing Products. Risk C: Monitor therapy
Cannabinoid-Containing Products: CNS Depressants may enhance the CNS depressant effect of Cannabinoid-Containing Products. Risk C: Monitor therapy
Chloral Betaine: May enhance the adverse/toxic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Chlormethiazole: May enhance the CNS depressant effect of CNS Depressants. Management: Monitor closely for evidence of excessive CNS depression. The chlormethiazole labeling states that an appropriately reduced dose should be used if such a combination must be used. Risk D: Consider therapy modification
Chlorphenesin Carbamate: May enhance the adverse/toxic effect of CNS Depressants. Risk C: Monitor therapy
Chlorprothixene: Agents with Clinically Relevant Anticholinergic Effects may enhance the anticholinergic effect of Chlorprothixene. Risk C: Monitor therapy
Cimetropium: Agents with Clinically Relevant Anticholinergic Effects may enhance the anticholinergic effect of Cimetropium. Risk X: Avoid combination
CloZAPine: Agents with Clinically Relevant Anticholinergic Effects may enhance the constipating effect of CloZAPine. Management: Consider alternatives to this combination whenever possible. If combined, monitor closely for signs and symptoms of gastrointestinal hypomotility and consider prophylactic laxative treatment. Risk D: Consider therapy modification
CNS Depressants: May enhance the adverse/toxic effect of other CNS Depressants. Risk C: Monitor therapy
CYP2D6 Inhibitors (Strong): May increase the serum concentration of Chlorpheniramine. Risk C: Monitor therapy
Daridorexant: May enhance the CNS depressant effect of CNS Depressants. Management: Dose reduction of daridorexant and/or any other CNS depressant may be necessary. Use of daridorexant with alcohol is not recommended, and the use of daridorexant with any other drug to treat insomnia is not recommended. Risk D: Consider therapy modification
DexmedeTOMIDine: CNS Depressants may enhance the CNS depressant effect of DexmedeTOMIDine. Management: Monitor for increased CNS depression during coadministration of dexmedetomidine and CNS depressants, and consider dose reductions of either agent to avoid excessive CNS depression. Risk D: Consider therapy modification
Difelikefalin: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Dimethindene (Systemic): Agents with Clinically Relevant Anticholinergic Effects may enhance the anticholinergic effect of Dimethindene (Systemic). Risk C: Monitor therapy
Dimethindene (Topical): May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Doxylamine: CNS Depressants may enhance the CNS depressant effect of Doxylamine. Risk C: Monitor therapy
DroPERidol: May enhance the CNS depressant effect of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (eg, opioids, barbiturates) with concomitant use. Risk D: Consider therapy modification
Eluxadoline: Agents with Clinically Relevant Anticholinergic Effects may enhance the constipating effect of Eluxadoline. Risk X: Avoid combination
Esketamine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Flunarizine: CNS Depressants may enhance the CNS depressant effect of Flunarizine. Risk X: Avoid combination
Flunitrazepam: CNS Depressants may enhance the CNS depressant effect of Flunitrazepam. Management: Reduce the dose of CNS depressants when combined with flunitrazepam and monitor patients for evidence of CNS depression (eg, sedation, respiratory depression). Use non-CNS depressant alternatives when available. Risk D: Consider therapy modification
Fosphenytoin-Phenytoin: Chlorpheniramine may increase the serum concentration of Fosphenytoin-Phenytoin. Risk C: Monitor therapy
Gastrointestinal Agents (Prokinetic): Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Gastrointestinal Agents (Prokinetic). Risk C: Monitor therapy
Glucagon: Agents with Clinically Relevant Anticholinergic Effects may enhance the adverse/toxic effect of Glucagon. Specifically, the risk of gastrointestinal adverse effects may be increased. Risk C: Monitor therapy
Glycopyrrolate (Oral Inhalation): Agents with Clinically Relevant Anticholinergic Effects may enhance the anticholinergic effect of Glycopyrrolate (Oral Inhalation). Risk X: Avoid combination
Glycopyrronium (Topical): May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid combination
Haloperidol: QT-prolonging Agents (Indeterminate Risk - Caution) may enhance the QTc-prolonging effect of Haloperidol. Risk C: Monitor therapy
Hyaluronidase: Antihistamines may diminish the therapeutic effect of Hyaluronidase. Risk C: Monitor therapy
HydrOXYzine: May enhance the CNS depressant effect of CNS Depressants. Management: Consider a decrease in the CNS depressant dose, as appropriate, when used together with hydroxyzine. Increase monitoring of signs/symptoms of CNS depression in any patient receiving hydroxyzine together with another CNS depressant. Risk D: Consider therapy modification
Ipratropium (Nasal): May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Ipratropium (Oral Inhalation): May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid combination
Isoproterenol: Chlorpheniramine may enhance the therapeutic effect of Isoproterenol. Risk C: Monitor therapy
Itopride: Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Itopride. Risk C: Monitor therapy
Ixabepilone: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Kava Kava: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Kratom: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Lemborexant: May enhance the CNS depressant effect of CNS Depressants. Management: Dosage adjustments of lemborexant and of concomitant CNS depressants may be necessary when administered together because of potentially additive CNS depressant effects. Close monitoring for CNS depressant effects is necessary. Risk D: Consider therapy modification
Levosulpiride: Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Levosulpiride. Risk X: Avoid combination
Lisuride: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Lofexidine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Loxapine: CNS Depressants may enhance the CNS depressant effect of Loxapine. Risk D: Consider therapy modification
Magnesium Sulfate: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Mavorixafor: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Risk X: Avoid combination
Methotrimeprazine: CNS Depressants may enhance the CNS depressant effect of Methotrimeprazine. Methotrimeprazine may enhance the CNS depressant effect of CNS Depressants. Management: Reduce the usual dose of CNS depressants by 50% if starting methotrimeprazine until the dose of methotrimeprazine is stable. Monitor patient closely for evidence of CNS depression. Risk D: Consider therapy modification
Metoclopramide: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
MetyroSINE: CNS Depressants may enhance the sedative effect of MetyroSINE. Risk C: Monitor therapy
Mianserin: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Minocycline (Systemic): May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Mirabegron: Agents with Clinically Relevant Anticholinergic Effects may enhance the adverse/toxic effect of Mirabegron. Risk C: Monitor therapy
Nabilone: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Nitroglycerin: Agents with Clinically Relevant Anticholinergic Effects may decrease the absorption of Nitroglycerin. Specifically, anticholinergic agents may decrease the dissolution of sublingual nitroglycerin tablets, possibly impairing or slowing nitroglycerin absorption. Risk C: Monitor therapy
Olopatadine (Nasal): May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Opioid Agonists: CNS Depressants may enhance the CNS depressant effect of Opioid Agonists. Management: Avoid concomitant use of opioid agonists and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Risk D: Consider therapy modification
Orphenadrine: CNS Depressants may enhance the CNS depressant effect of Orphenadrine. Risk X: Avoid combination
Oxatomide: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid combination
Oxomemazine: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Oxybate Salt Products: CNS Depressants may enhance the CNS depressant effect of Oxybate Salt Products. Management: Consider alternatives to this combination when possible. If combined, dose reduction or discontinuation of one or more CNS depressants (including the oxybate salt product) should be considered. Interrupt oxybate salt treatment during short-term opioid use Risk D: Consider therapy modification
OxyCODONE: CNS Depressants may enhance the CNS depressant effect of OxyCODONE. Management: Avoid concomitant use of oxycodone and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Risk D: Consider therapy modification
Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. Risk X: Avoid combination
Peginterferon Alfa-2b: May decrease the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Peginterferon Alfa-2b may increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Risk C: Monitor therapy
Perampanel: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Piribedil: CNS Depressants may enhance the CNS depressant effect of Piribedil. Risk C: Monitor therapy
Pitolisant: Antihistamines may diminish the therapeutic effect of Pitolisant. Risk X: Avoid combination
Potassium Chloride: Agents with Clinically Relevant Anticholinergic Effects may enhance the ulcerogenic effect of Potassium Chloride. Management: Patients on drugs with substantial anticholinergic effects should avoid using any solid oral dosage form of potassium chloride. Risk X: Avoid combination
Potassium Citrate: Agents with Clinically Relevant Anticholinergic Effects may enhance the ulcerogenic effect of Potassium Citrate. Management: Patients on drugs with substantial anticholinergic effects should avoid using any solid oral dosage form of potassium citrate. Risk X: Avoid combination
Pramipexole: CNS Depressants may enhance the sedative effect of Pramipexole. Risk C: Monitor therapy
Pramlintide: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. These effects are specific to the GI tract. Risk X: Avoid combination
Procarbazine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
QT-prolonging Agents (Highest Risk): QT-prolonging Agents (Indeterminate Risk - Caution) may enhance the QTc-prolonging effect of QT-prolonging Agents (Highest Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
QuiNIDine: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Ramosetron: Agents with Clinically Relevant Anticholinergic Effects may enhance the constipating effect of Ramosetron. Risk C: Monitor therapy
Revefenacin: Agents with Clinically Relevant Anticholinergic Effects may enhance the anticholinergic effect of Revefenacin. Risk X: Avoid combination
Rivastigmine: Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Rivastigmine. Rivastigmine may diminish the therapeutic effect of Agents with Clinically Relevant Anticholinergic Effects. Management: Use of rivastigmine with an anticholinergic agent is not recommended unless clinically necessary. If the combination is necessary, monitor for reduced anticholinergic effects. Risk D: Consider therapy modification
Ropeginterferon Alfa-2b: CNS Depressants may enhance the adverse/toxic effect of Ropeginterferon Alfa-2b. Specifically, the risk of neuropsychiatric adverse effects may be increased. Management: Avoid coadministration of ropeginterferon alfa-2b and other CNS depressants. If this combination cannot be avoided, monitor patients for neuropsychiatric adverse effects (eg, depression, suicidal ideation, aggression, mania). Risk D: Consider therapy modification
ROPINIRole: CNS Depressants may enhance the sedative effect of ROPINIRole. Risk C: Monitor therapy
Rotigotine: CNS Depressants may enhance the sedative effect of Rotigotine. Risk C: Monitor therapy
Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Risk C: Monitor therapy
Secretin: Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Secretin. Management: Avoid concomitant use of anticholinergic agents and secretin. Discontinue anticholinergic agents at least 5 half-lives prior to administration of secretin. Risk D: Consider therapy modification
Suvorexant: CNS Depressants may enhance the CNS depressant effect of Suvorexant. Management: Dose reduction of suvorexant and/or any other CNS depressant may be necessary. Use of suvorexant with alcohol is not recommended, and the use of suvorexant with any other drug to treat insomnia is not recommended. Risk D: Consider therapy modification
Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Risk X: Avoid combination
Thiazide and Thiazide-Like Diuretics: Agents with Clinically Relevant Anticholinergic Effects may increase the serum concentration of Thiazide and Thiazide-Like Diuretics. Risk C: Monitor therapy
Tiotropium: Agents with Clinically Relevant Anticholinergic Effects may enhance the anticholinergic effect of Tiotropium. Risk X: Avoid combination
Topiramate: Agents with Clinically Relevant Anticholinergic Effects may enhance the adverse/toxic effect of Topiramate. Risk C: Monitor therapy
Tranylcypromine: May enhance the anticholinergic effect of Antihistamines, First Generation. Risk X: Avoid combination
Trimeprazine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Umeclidinium: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid combination
Valerian: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Zolpidem: CNS Depressants may enhance the CNS depressant effect of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Risk D: Consider therapy modification
Zuranolone: May enhance the CNS depressant effect of CNS Depressants. Management: Consider alternatives to the use of zuranolone with other CNS depressants or alcohol. If combined, consider a zuranolone dose reduction and monitor patients closely for increased CNS depressant effects. Risk D: Consider therapy modification
Outcome data following maternal use of chlorpheniramine during pregnancy are available (Aselton 1985; Diav-Citrin 2003; Gilboa 2009; Gilboa 2014; Heinonen 1977; Jick 1981; Li 2013).
Algorithms are available for the treatment of acute rhinitis and urticaria. First-generation oral antihistamines are generally not recommended for use in pregnant patients due to side effects (AAAAI/ACAAI [Dykewicz 2020]; EAACI [Zuberbier 2022]). However, chlorpheniramine may be used when a first-generation antihistamine is needed during pregnancy (Murase 2014; Stefaniak 2022).
Competes with histamine for H1-receptor sites on effector cells in the gastrointestinal tract, blood vessels, and respiratory tract
Note: Data from chlorpheniramine maleate:
Distribution: Vd: Children and Adolescents 6 to 16 years: 7 ± 2.8 L/kg (Simons 1982); Adults: 6-12 L/kg (Paton 1985)
Protein binding: ~70% (Rumore 1984).
Metabolism: Hepatic via CYP450 enzymes (including CYP2D6 and other unidentified enzymes) to active and inactive metabolites; significant first-pass effect (Sharma 2003)
Half-life elimination: Serum: Children and Adolescents 6 to 16 years: 13.1 ± 6.6 hours (range: 6.3 to 23.1 hours) (Simons, 1982); Adults: 14-24 hours (Paton 1985)
Time to peak: Children and Adolescents 6 to 16 years: Oral : 2.5 ± 1.5 hours (range: 1 to 6 hours) (Simons 1982); Adults: 2-3 hours (Sharma 2003)
Excretion: Urine (Sharma 2003)
Altered kidney function: Severe chronic kidney impairment: Half-life prolonged to 280 to 330 hours (Paton 1985).
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