aspirin/chlorpheniramine/dextromethorphan (Alka-Seltzer Plus Flu)

Dosing and uses of Alka-Seltzer Plus Flu (aspirin/chlorpheniramine/dextromethorphan)

• Adult
• Pediatric

 

Adult dosage forms and strengths

aspirin/chlorpheniramine/dextromethorphan

tablet, effervescent

• 500mg/2mg/15mg

 

Temporary Relief of Common Cold Cough & Upper Respiratory Symptoms

Alka-Seltzer Plus Flu: 2 tablets fully dissolved in 4 oz of water q6hr; not to exceed 8 tablets/day

 

Pediatric dosage forms and strengths

aspirin/chlorpheniramine/dextromethorphan

tablet, effervescent

• 500mg/2mg/15mg

 

Temporary Relief of Common Cold Cough & Upper Respiratory Symptoms

Alka-Seltzer Plus Flu

• <12 years: Ask a pediatrician
• >12 years: 2 tablets fully dissolved in 4 oz of water q6hr; not to exceed 8 tablets/day

 

Alka-Seltzer Plus Flu (aspirin/chlorpheniramine/dextromethorphan) adverse (side) effects

Frequency not defined

Agitation

Agranulocytosis

Anorexia

Cerebral edema

Coma

Confusion

Depression

Dizziness

Dyspepsia

Dysrhythmias

Euphoria

Fatigue

GI bleeding

Headache

Hemolytic anemia

Hives

Hypotension

Insomnia

Irritability

Lethargy

May potentiate peptic ulcer and cause stomach distress or heartburn

Nausea

Palpitations

Prolonged prothrombin time

Rashes

Sedation

Subdural or intracranial hemorrhage

Tachycardia

Thickening of bronchial secretions

Thrombocytopenia

Tremors

Ulceration and perforation

Vomiting

Wheezing

 

Warnings

Contraindications

Hypersensitivity

Liver damage

Hypoprothrombinemia

Vitamin K deficiency

Bleeding disorders

Asthma

Due to association of aspirin with Reye syndrome, do not use in children (<16 years) with viral infections

Narrow-angle glaucoma

Symptomatic prostate hypertrophy

Bladder-neck obstruction

Stenosing peptic ulcer

 

Cautions

Aspirin may cause transient decrease in renal function and aggravate chronic kidney disease; avoid use in patients with severe anemia, with history of blood coagulation defects, or taking anticoagulants

Dextromethorphan: do not take for persistent or chronic cough associated with smoking, asthma, or emphysema, or if it is accompanied by excessive phlegm unless directed by a healthcare provider; may slow respiration rate

Chlorpheniramine: may cause significant confusional symptoms; not for administration to premature or full-term neonates

 

Pregnancy and lactation

Pregnancy category: D; avoid aspirin during pregnancy, particularly in third trimester (risk of premature closure of ductus arteriosus)

Lactation: excreted in breast milk; do not breast feed

Pregnant or breastfeeding patients should seek advice of health professional before using OTC drugs

 

Pregnancy categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.

 

Pharmacology of Alka-Seltzer Plus Flu (aspirin/chlorpheniramine/dextromethorphan)

Mechanism of action

Aspirin: stronger inhibitor of both prostaglandin synthesis and platelet aggregation than other salicylic acid derivatives; acetyl group is responsible for inactivation of cyclooxygenase via acetylation; hydrolyzed rapidly in plasma, and elimination follows zero order pharmacokinetics

Aspirin irreversibly inhibits platelet aggregation by inhibiting platelet cyclooxygenase; this leads to inhibition of conversion of arachidonic acid to PGI2 (potent vasodilator and inhibitor of platelet activation) and thromboxane A2 (potent vasoconstrictor and platelet aggregate)

Chlorpheniramine: blocks muscle responses in histamine and antagonizes constrictor effects of histamine on respiratory smooth muscle

Dextromethorphan: cough suppressant that acts centrally on cough center in medulla

 

Pharmacokinetics

Aspirin

• Bioavailability: 80-100%
• Onset: 5-30 min (PO); 1-2 hr (PR)
• Duration: 3-6 hr (PO); >7 hr (PR)
• Peak plasma time: 0.25-3 hr (PO); 4-5hr (PR)
• Vd: 0.15-0.2 L/kg
• Protein binding: 90-95%
• Metabolism: Liver (microsomal enzyme system)
• Half-life: 2-3 hr (low dose); 15-30 hr (higher dose)
• Renal clearance: 80-100%
• Excretion: Urine (80-100%)

Chlorpheniramine

• Peak plasma time: 2-3 hr  
• Peak plasma concentration: 7.2 ng/mL
• Distribution (Vd): 4-7 L/kg (children); 6-12 L/kg (adults)
• Metabolism: GI mucosa, liver
• Excretion: Urine
• Half-life : 10-13 hr (children); 14-24 hr (adults)

Dextromethorphan

• Onset: 15-30 min
• Duration: 3-6 hr
• Metabolism: Hepatic P450 enzyme CYP2D6
• Excretion: Urine
• Half-life: 2-4 hr (extensive metabolizers); 24 hr (poor metabolizers)
• Peak plasma time: 2-3 hr