Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ACULAR PRESERVATIVE FREE vs AMMONIUM CHLORIDE IN PLASTIC CONTAINER
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Ketorolac tromethamine is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase (COX-1 and COX-2) enzymes, thereby reducing prostaglandin synthesis. It produces anti-inflammatory and analgesic effects.
Ammonium chloride is an acidifying agent that provides chloride ions and ammonium ions. The ammonium ion is converted to urea in the liver, releasing hydrogen ions, which leads to metabolic acidosis. It also directly stimulates the respiratory center and promotes diuresis by increasing the osmotic load.
FDA-approved: Treatment of ocular inflammation and pain following cataract surgery and corneal refractive surgery.,Off-label: Relief of seasonal allergic conjunctivitis symptoms, management of cystoid macular edema, and treatment of postoperative inflammation in other ocular procedures.
Treatment of metabolic alkalosis,Urinary acidification to facilitate excretion of weak bases in poisoning,Hypochloremic states
1 drop into affected eye(s) four times daily (every 6 hours). Instill into conjunctival sac. Shake well before use.
For metabolic alkalosis: 1-2 g intravenously every 6-12 hours as needed; maximum 6 g/day. For hypochloremic states: 1-2 g orally or intravenously 2-3 times daily.
Terminal elimination half-life is approximately 5-6 hours in adults, but can be prolonged in elderly patients (up to 8-9 hours) and in patients with renal impairment (up to 13-19 hours).
Terminal elimination half-life is approximately 2-4 hours in adults with normal hepatic and renal function. This reflects the rapid conversion of ammonium to urea in the liver and subsequent renal clearance. Half-life may be prolonged in hepatic or renal impairment.
Ketorolac undergoes hepatic metabolism via hydroxylation and conjugation (glucuronidation) to inactive metabolites. It is primarily metabolized by CYP2D6 and CYP3A4 isoenzymes, with renal excretion of metabolites and unchanged drug.
Metabolized primarily in the liver via the urea cycle; ammonium ion is converted to urea, releasing hydrogen ions. The chloride ion is excreted renally.
Primarily renal excretion of metabolites and unchanged drug; approximately 80% of a dose is excreted in urine as ketorolac and its hydroxy metabolites, with about 6% excreted in feces.
Renal: >99% as ammonium and chloride ions. The kidney converts ammonia to urea, which is excreted in urine. Fecal and biliary elimination are negligible.
99% bound to plasma proteins, primarily albumin.
<1% bound to plasma proteins. Ammonium ions are primarily free in plasma.
0.15-0.25 L/kg after oral administration; for ophthalmic use, systemic absorption is minimal, so Vd is not clinically meaningful.
Approximately 0.2-0.3 L/kg, reflecting distribution mainly in extracellular fluid. Ammonium ions do not significantly penetrate cells under normal conditions.
Ophthalmic administration: Systemic bioavailability is approximately 0.5-1% after ocular instillation due to low corneal penetration and rapid clearance; oral bioavailability is 100%.
Oral: ~100% absorbed from the gastrointestinal tract, though first-pass hepatic metabolism (urea cycle) limits systemic availability of intact ammonium. Intravenous: 100% bioavailable.
No dosage adjustment required for renal impairment. Drug is minimally absorbed systemically.
Contraindicated in severe renal impairment (GFR <30 m L/min). For GFR 30-50 m L/min: reduce dose by 50% and monitor serum chloride and ammonia. For GFR >50 m L/min: no adjustment necessary.
No dosage adjustment required for hepatic impairment. Drug is minimally absorbed systemically.
Contraindicated in severe hepatic insufficiency (Child-Pugh class C). For Child-Pugh class B: use with caution, reduce dose by 50% and monitor ammonia levels. For Child-Pugh class A: no adjustment necessary.
Children ≥3 years: 1 drop into affected eye(s) four times daily. Safety and efficacy in children <3 years not established.
For metabolic alkalosis: 50-100 mg/kg intravenously every 6-8 hours; maximum 2 g/day. For hypochloremic states: 75 mg/kg/day orally in divided doses.
No specific dosage adjustment required. Use same dose as adults; monitor for tolerability.
Start at lower end of dosing range (e.g., 1 g intravenously every 12 hours) due to age-related decline in renal function; monitor serum electrolytes and renal function closely.
NSAIDs may increase the risk of serious cardiovascular events (e.g., myocardial infarction, stroke) and gastrointestinal events (e.g., bleeding, ulceration, perforation). However, due to low systemic absorption with ophthalmic use, this boxed warning is less clinically relevant but still applies.
None
Use with caution in patients with compromised ocular surface, history of herpes simplex keratitis, bleeding tendencies, or those on anticoagulants. Prolonged use may delay wound healing. Monitor for signs of corneal epithelial breakdown or infection.
Use with caution in patients with hepatic impairment (risk of ammonia toxicity), renal dysfunction, or respiratory acidosis. Monitor acid-base status, serum chloride, and ammonia levels. Avoid rapid infusion to prevent severe acidosis. Not for use in severe hepatic insufficiency.
Hypersensitivity to ketorolac or any component of the formulation; patients with active ocular infection or advanced dry eye; history of asthma, urticaria, or allergic-type reactions to aspirin or other NSAIDs.
Severe hepatic insufficiency; severe renal failure with oliguria or anuria; primary respiratory acidosis; hypokalemia (due to risk of exacerbating potassium loss); hypersensitivity to ammonium chloride.
No known food interactions. No dietary restrictions required.
Avoid excessive dietary intake of chloride-rich foods (e.g., table salt, processed foods) as it may affect treatment. No specific food restrictions, but maintain balanced diet as advised by physician.
FDA Pregnancy Category C. No adequate studies in pregnant women. In animal studies, ketorolac tromethamine (active ingredient) was not teratogenic in rats or rabbits at doses up to 1.5-3 times the human exposure. However, because NSAIDs can cause premature closure of the ductus arteriosus and oligohydramnios in the third trimester, use is contraindicated after 30 weeks gestation. In first and second trimesters, use only if potential benefit justifies potential fetal risk.
FDA Pregnancy Category C. Ammonium chloride crosses the placenta. First trimester: insufficient human data; animal studies not available; theoretical risk of fetal acidosis if maternal acidosis induced. Second/third trimester: may cause fetal acidosis, electrolyte disturbances, and potential for fetal harm if maternal overdose or pre-existing acidosis.
Ketorolac is excreted in human milk following oral administration. After a single intramuscular dose of 10 mg, the milk-to-plasma (M/P) ratio was 0.037. Low levels are expected in breastmilk; however, due to potential adverse effects of NSAIDs on neonates, caution is advised. Use is generally avoided in nursing mothers, especially with premature infants or those with thrombocytopenia or renal impairment.
No human data on excretion in breast milk. M/P ratio unknown. Caution advised; consider risk of infant acidosis and ammonia toxicity if exposed.
No specific pharmacokinetic studies in pregnancy. Dosing should be at the lowest effective dose for the shortest duration. Avoid use after 30 weeks gestation. No adjustment for first or second trimester unless renal function changes.
No established dose adjustment for pregnancy. Decreased GI motility and increased plasma volume may alter absorption and distribution; however, dosing should be guided by clinical response and frequent monitoring of acid-base and electrolyte status. Avoid overdosing to prevent maternal and fetal acidosis.
ACULAR (ketorolac tromethamine ophthalmic solution) is an NSAID for ocular use. Preservative-free formulation is indicated for single-use to avoid corneal toxicity. Apply with caution in patients with bleeding disorders or those on anticoagulants due to risk of ocular bleeding. Prolonged use may delay corneal healing. Monitor for signs of keratitis or conjunctival hyperemia.
Ammonium chloride is used to treat severe metabolic alkalosis by providing chloride ions and generating mild metabolic acidosis. Monitor serum chloride, bicarbonate, and p H closely during infusion. Avoid in patients with severe hepatic impairment or renal failure. Infusion may cause local irritation; ensure proper IV access.
Use exactly as prescribed; do not touch the dropper tip to any surface to avoid contamination.,Each single-use vial is for one dose only; discard after use to prevent infection.,Remove contact lenses before instillation and wait 10 minutes before reinserting.,Do not drive or operate machinery if vision is blurry after application.,Report eye pain, increased redness, or vision changes to your doctor immediately.
This medication is used to correct an acid-base imbalance in your blood.,It will be given intravenously (IV) by a healthcare professional.,Report any burning, pain, or redness at the IV site immediately.,Do not consume large amounts of salt or salty foods unless directed.,Tell your doctor if you have liver or kidney disease.
No interactions on record
"Ammonium chloride, an acidifying agent, reduces urinary pH, which increases the renal clearance of lisdexamfetamine and its active metabolite d-amphetamine. This accelerated elimination leads to decreased systemic exposure and potentially diminished therapeutic efficacy of lisdexamfetamine. Clinically, patients may experience reduced symptom control for ADHD or binge eating disorder, requiring dose adjustments or alternative therapies."
"Sufentanil, a potent opioid analgesic, may increase renal excretion of ammonium chloride by promoting diuresis through opioid-induced release of antidiuretic hormone (ADH) and subsequent water reabsorption, leading to dilutional acidosis and enhanced ammonium excretion. This interaction can result in reduced serum ammonium levels and decreased efficacy of ammonium chloride as an acidifying agent, potentially compromising its therapeutic effect in metabolic alkalosis or urinary tract infections. Clinical outcomes may include incomplete correction of metabolic alkalosis or reduced antimicrobial activity of ammonium chloride in the urine."
"Ammonium chloride acidifies the urine, which increases the renal excretion of amphetamine by favoring its ionized form in the tubular lumen, thereby reducing its reabsorption. This leads to a decreased serum concentration of amphetamine and potentially diminished therapeutic efficacy. Clinically, patients may experience reduced mood-elevating or stimulant effects, requiring dose adjustment."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ACULAR PRESERVATIVE FREE vs AMMONIUM CHLORIDE IN PLASTIC CONTAINER, answered by our medical review team.
ACULAR PRESERVATIVE FREE is a NSAID Ophthalmic that works by Ketorolac tromethamine is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase (COX-1 and COX-2) enzymes, thereby reducing prostaglandin synthesis. It produces anti-inflammatory and analgesic effects.. AMMONIUM CHLORIDE IN PLASTIC CONTAINER is a Expectorant/Systemic Acidifier that works by Ammonium chloride is an acidifying agent that provides chloride ions and ammonium ions. The ammonium ion is converted to urea in the liver, releasing hydrogen ions, which leads to metabolic acidosis. It also directly stimulates the respiratory center and promotes diuresis by increasing the osmotic load.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ACULAR PRESERVATIVE FREE and AMMONIUM CHLORIDE IN PLASTIC CONTAINER 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 ACULAR PRESERVATIVE FREE is: 1 drop into affected eye(s) four times daily (every 6 hours). Instill into conjunctival sac. Shake well before use.. The standard adult dose of AMMONIUM CHLORIDE IN PLASTIC CONTAINER is: For metabolic alkalosis: 1-2 g intravenously every 6-12 hours as needed; maximum 6 g/day. For hypochloremic states: 1-2 g orally or intravenously 2-3 times daily.. 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 ACULAR PRESERVATIVE FREE and AMMONIUM CHLORIDE IN PLASTIC CONTAINER 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. ACULAR PRESERVATIVE FREE is classified as Category C. FDA Pregnancy Category C. No adequate studies in pregnant women. In animal studies, ketorolac tromethamine (active ingredient) was not teratogenic in rats or rabbits at doses up to. AMMONIUM CHLORIDE IN PLASTIC CONTAINER is classified as Category C. FDA Pregnancy Category C. Ammonium chloride crosses the placenta. First trimester: insufficient human data; animal studies not available; theoretical risk of fetal acidosis if mate. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.