Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ACUVAIL vs GUAIFENESIN AND DEXTROMETHORPHAN HYDROBROMIDE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Ketorolac tromethamine, a nonsteroidal anti-inflammatory drug (NSAID), inhibits prostaglandin synthesis by blocking cyclooxygenase (COX-1 and COX-2) enzymes. This reduces ocular inflammation and pain.
Guaifenesin is an expectorant that increases respiratory tract fluid secretions, reducing mucus viscosity. Dextromethorphan is a centrally acting cough suppressant that binds to NMDA receptors and sigma-1 receptors, elevating the cough threshold.
Reduction of ocular pain and inflammation following cataract surgery,Treatment of ocular itching associated with seasonal allergic conjunctivitis
Temporary relief of cough due to minor throat and bronchial irritation (FDA-approved),Off-label: symptomatic treatment of upper respiratory tract infections with cough and congestion
1 drop in the affected eye 4 times daily.
For adults and children ≥12 years: 10 m L (200 mg guaifenesin, 20 mg dextromethorphan) orally every 4 hours, not to exceed 60 m L (1200 mg guaifenesin, 120 mg dextromethorphan) per 24 hours.
Terminal elimination half-life is approximately 46 minutes in the aqueous humor following ocular administration in humans.
Guaifenesin: 1-2 hours; Dextromethorphan: 3-6 hours (extensive metabolizers), 18-24 hours (poor metabolizers due to CYP2D6 polymorphism).
Primarily hepatic via conjugation with glucuronic acid; minor role of cytochrome P450 enzymes. Approximately 50% is excreted as parent drug and metabolites in urine.
Guaifenesin is metabolized by oxidation and demethylation; dextromethorphan is extensively metabolized by CYP2D6 to dextrorphan (active metabolite) and other metabolites.
Primarily renal excretion of metabolites; less than 1% excreted unchanged. Biliary/fecal elimination accounts for <10%.
Guaifenesin: ~60% renal (metabolites), ~35% fecal; Dextromethorphan: ~70% renal (parent and metabolites, 45% as unchanged dextrorphan), ~20% biliary/fecal.
>99% bound to plasma proteins, primarily albumin.
Guaifenesin: negligible (<10%); Dextromethorphan: ~60-70% (mainly albumin and alpha-1-acid glycoprotein).
Intravenous administration in animals suggests Vd ~0.15 L/kg, indicating limited distribution; clinically, it distributes into aqueous humor after topical dosing.
Guaifenesin: 1.2 L/kg (distributes into tissues); Dextromethorphan: 5-7 L/kg (large Vd due to high tissue binding).
Ocular bioavailability is dependent on formulation; systemic bioavailability after topical ocular administration is extremely low (<1%).
Oral: Guaifenesin ~95%; Dextromethorphan ~11% (extensive first-pass metabolism, variable due to CYP2D6).
No adjustment required. Drug is minimally systemically absorbed.
No specific guidelines; use with caution in severe renal impairment (Cr Cl <30 m L/min) due to potential accumulation of dextromethorphan metabolite.
No adjustment required. Drug is minimally systemically absorbed.
For dextromethorphan: Child-Pugh class C: consider reducing dose by 50% or avoid use; Child-Pugh A/B: no specific adjustment but monitor for CNS effects.
Safety and efficacy in pediatric patients have not been established.
Children 6-11 years: 5 m L (100 mg guaifenesin, 10 mg dextromethorphan) every 4 hours, max 30 m L/day. Children 2-5 years: 2.5 m L (50 mg guaifenesin, 5 mg dextromethorphan) every 4 hours, max 15 m L/day. Not for children <2 years.
No specific dosage adjustment is recommended; use same dose as younger adults.
Use the lowest effective dose; consider starting with 5 m L (100 mg guaifenesin, 10 mg dextromethorphan) every 4-6 hours due to increased risk of sedation and anticholinergic effects.
No black box warning for ophthalmic use; however, systemic NSAIDs carry risk of serious cardiovascular and gastrointestinal events. Ophthalmic use rarely associated with corneal adverse events.
None.
Use with caution in patients with bleeding disorders or those on anticoagulants; may prolong bleeding time. Avoid in patients with known hypersensitivities to NSAIDs or aspirin. Can cause corneal keratopathy; discontinue if corneal epithelial breakdown occurs.
Avoid use in patients with chronic cough (e.g., smoking, asthma, emphysema) or cough with excessive phlegm.,Concomitant use with MAOIs or within 2 weeks of MAOI use is contraindicated.,Dextromethorphan abuse potential; use caution with CYP2D6 inhibitors.
Hypersensitivity to any component of the formulation. Active corneal epithelial defect. Patients with aspirin-sensitive asthma.
Hypersensitivity to guaifenesin or dextromethorphan,Concurrent use or recent use (within 2 weeks) of monoamine oxidase inhibitors (MAOIs),Severe hypertension, coronary artery disease, or narrow-angle glaucoma (due to sympathomimetic effects if combined with decongestants; note: this combination alone does not contain decongestants, but caution applies)
No specific food interactions; systemic absorption is minimal with ophthalmic use. Avoid concurrent use of other NSAID eye drops due to additive irritation.
No significant food interactions; avoid alcohol as it may increase sedation and dizziness.
Acuvail (ketorolac tromethamine ophthalmic solution) is classified as FDA Pregnancy Category C. Systemic exposure after ocular administration is minimal; however, NSAIDs may cause premature closure of the ductus arteriosus and oligohydramnios in the third trimester. Use during the first and second trimesters should be limited to cases where potential benefit outweighs risk; avoid during the third trimester due to risk of fetal harm.
Guaifenesin: Limited human data; animal studies show no teratogenicity at clinically relevant doses. Dextromethorphan: No increased risk of major malformations in first trimester; animal studies show no teratogenicity. Avoid excessive doses in third trimester due to potential neonatal withdrawal or respiratory depression. Overall, both agents are considered low risk but use only if clearly needed.
Ketorolac is excreted in human milk following systemic administration, but ocular doses produce negligible systemic levels. The M/P ratio is not determined for ophthalmic use. Use with caution in nursing mothers, as the clinical significance is likely low due to minimal systemic absorption.
Guaifenesin: Excreted in breast milk in small amounts; unlikely to cause adverse effects in infants. Dextromethorphan: Excreted in breast milk; limited data suggest low infant exposure (M/P ratio not established). Both are considered compatible with breastfeeding; use lowest effective dose and monitor infant for sedation or respiratory depression.
No dosage adjustment is required for ophthalmic use during pregnancy, as systemic exposure is negligible. However, avoid use in third trimester due to risks. Pharmacokinetic changes in pregnancy do not significantly alter ocular delivery.
No pharmacokinetic data to support dose adjustments during pregnancy; use lowest effective dose for shortest duration. Guaifenesin: increased renal clearance in pregnancy may theoretically reduce efficacy, but no dose adjustment recommended. Dextromethorphan: metabolism by CYP2D6 may be affected by pregnancy; avoid exceeding standard doses.
Acuvail (ketorolac tromethamine ophthalmic solution 0.45%) is a nonsteroidal anti-inflammatory drug (NSAID) for ocular use. It is preserved with sodium chloride and not benzalkonium chloride, reducing corneal epithelial toxicity. Administer 1 drop twice daily for ocular pain and inflammation following cataract surgery. Use caution in patients with bleeding tendencies or those on anticoagulants due to risk of increased ocular bleeding. Monitor for corneal epithelial defects and keratitis, especially with prolonged use.
Monitor for sedation and dizziness, especially in elderly; avoid use with MAOIs due to serotonin syndrome risk; dextromethorphan has abuse potential at high doses; use caution in patients with chronic cough due to smoking, asthma, or COPD; guaifenesin may cause renal calculi with prolonged high doses.
Wash hands before each use; do not touch tip of bottle to eye or any surface to avoid contamination.,Remove contact lenses before instillation and wait at least 15 minutes before reinserting.,Contact your doctor if you experience eye pain, redness, vision changes, or if symptoms worsen.,Do not use this medication while wearing contact lenses unless directed by your doctor.,Store at room temperature, keep bottle tightly closed when not in use, and discard within 28 days of opening.
Do not exceed recommended doses; high doses can cause serious side effects including hallucinations and addiction.,Avoid driving or operating machinery if you feel dizzy or drowsy.,Do not use with other cough and cold medications to avoid overdose.,Increase fluid intake to help loosen mucus.,Stop use and consult a doctor if cough persists more than 7 days or comes with fever, rash, or headache.,Inform your doctor about all medications you take, especially MAOIs or SSRIs.,Keep out of reach of children; accidental overdose may be fatal in children.
No interactions on record
"The combination of dextromethorphan, a centrally acting antitussive with NMDA receptor antagonist and sigma-1 receptor agonist properties, and aceprometazine, a phenothiazine neuroleptic with strong antihistaminergic and moderate anticholinergic and antidopaminergic effects, can result in additive central nervous system depression. This interaction may lead to excessive sedation, respiratory depression, impaired psychomotor function, and an increased risk of falls or cognitive impairment, particularly in elderly or debilitated patients. Concurrent use may also lower the seizure threshold, especially in patients with predisposing factors."
"Dextromethorphan, a serotonergic agent metabolized by CYP2D6, when combined with cariprazine, a dopamine D3/D2 receptor partial agonist, may increase the risk of serotonin syndrome due to additive serotonergic effects. Cariprazine can inhibit CYP2D6, reducing dextromethorphan clearance and elevating its plasma concentration, leading to enhanced serotonin activity. Clinically, patients may present with altered mental status, autonomic instability, and neuromuscular abnormalities."
"Dextromethorphan inhibits CYP2B6 and CYP2C9, which are involved in valproic acid metabolism. This results in decreased valproic acid clearance, potentially elevating valproic acid serum concentrations and increasing the risk of dose-dependent adverse effects such as hepatotoxicity, thrombocytopenia, and sedation. Concurrent use requires dose adjustment and close monitoring for signs of valproate toxicity."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ACUVAIL vs GUAIFENESIN AND DEXTROMETHORPHAN HYDROBROMIDE, answered by our medical review team.
ACUVAIL is a NSAID Ophthalmic that works by Ketorolac tromethamine, a nonsteroidal anti-inflammatory drug (NSAID), inhibits prostaglandin synthesis by blocking cyclooxygenase (COX-1 and COX-2) enzymes. This reduces ocular inflammation and pain.. GUAIFENESIN AND DEXTROMETHORPHAN HYDROBROMIDE is a Expectorant/Antitussive Combination that works by Guaifenesin is an expectorant that increases respiratory tract fluid secretions, reducing mucus viscosity. Dextromethorphan is a centrally acting cough suppressant that binds to NMDA receptors and sigma-1 receptors, elevating the cough threshold.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ACUVAIL and GUAIFENESIN AND DEXTROMETHORPHAN HYDROBROMIDE depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of ACUVAIL is: 1 drop in the affected eye 4 times daily.. The standard adult dose of GUAIFENESIN AND DEXTROMETHORPHAN HYDROBROMIDE is: For adults and children ≥12 years: 10 m L (200 mg guaifenesin, 20 mg dextromethorphan) orally every 4 hours, not to exceed 60 m L (1200 mg guaifenesin, 120 mg dextromethorphan) per 24 hours.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between ACUVAIL and GUAIFENESIN AND DEXTROMETHORPHAN HYDROBROMIDE in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. ACUVAIL is classified as Category C. Acuvail (ketorolac tromethamine ophthalmic solution) is classified as FDA Pregnancy Category C. Systemic exposure after ocular administration is minimal; however, NSAIDs may cause . GUAIFENESIN AND DEXTROMETHORPHAN HYDROBROMIDE is classified as Category C. Guaifenesin: Limited human data; animal studies show no teratogenicity at clinically relevant doses. Dextromethorphan: No increased risk of major malformations in first trimester; . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.