Pharmacology · Nonsteroidal anti-inflammatory drugs (NSAIDs)
Ketorolac !
An injectable NSAID with near-opioid pain relief for severe acute pain. Total use does not exceed 5 days because of its toxicity.
Updated 2026-11-01
Mechanism of action
Ketorolac is a non-selective NSAID that inhibits COX-1 and COX-2. It is a racemic mixture: the S form carries the analgesic activity. By blocking peripheral prostaglandin synthesis it markedly reduces pain, and by inhibiting platelet COX-1 it impairs platelet function.
- The S form inhibits COX-1 and COX-2
- Prostaglandin synthesis falls in injured tissue
- Strong pain relief without respiratory depression
- Platelet function is inhibited: higher bleeding risk
Pharmacokinetics
- Absorption
- Given intravenously or intramuscularly; the oral route only continues treatment started parenterally.
- Metabolism
- Partly in the liver.
- Elimination
- Mainly by the kidney; it accumulates in kidney disease and in older adults.
- Half-life
- About 5 to 6 hours for the racemic mixture.
- Onset and duration
- Peak pain relief comes in about 2 to 3 hours.
Indications
- Short-term management of moderately severe acute pain that needs opioid-level analgesia, mainly after surgery
Adverse effects
Common
- Headache
- Drowsiness and dizziness
- Diarrhoea, constipation and gas
- Mouth sores and sweating
Contraindications
- Hypersensitivity to the drug
- Asthma, urticaria or another allergic reaction after acetylsalicylic acid or another NSAID
- The setting of coronary artery bypass graft (CABG) surgery
- Active peptic ulcer, recent gastrointestinal bleeding or perforation, or a history of ulcer or gastrointestinal bleeding
- Advanced kidney disease or risk of renal failure from volume depletion
- Cerebrovascular bleeding, bleeding diathesis or incomplete haemostasis
- Labour and delivery
- As a prophylactic analgesic before major surgery
- Concurrent acetylsalicylic acid or other NSAIDs, probenecid or pentoxifylline
- Epidural or intrathecal administration (it contains alcohol)
Key interactions
- Acetylsalicylic acid and other NSAIDs
- Contraindicated: they add gastrointestinal, renal and bleeding toxicity.
- Probenecid
- Contraindicated: raises ketorolac levels.
- Pentoxifylline
- Contraindicated: raises the bleeding risk.
- Heparin, warfarin and other drugs that affect haemostasis
- May increase the risk of bleeding.
- ACE inhibitors, ARBs and diuretics
- Blunt their antihypertensive and diuretic effect; in older or volume-depleted patients they can precipitate acute kidney injury.
What is monitored
- Cumulative days of treatment (parenteral plus oral)
- Urine output, creatinine and volume status
- Signs of bleeding
- Gastrointestinal symptoms
Administration and safety
- The total combined duration (injection plus oral) does not exceed 5 days.
- Hypovolaemia is corrected before the first dose; the patient must be hydrated.
- Never given epidurally or intrathecally.
- Treatment for a severe allergic reaction is at hand when the first dose is given.
- Not indicated in children or for mild or chronic pain.
Nursing care
- Count the days of use and flag when the limit approaches.
- Check hydration, urine output and creatinine before and during treatment.
- Watch for bleeding from surgical wounds, black stools or vomiting blood.
- Confirm the patient is not receiving other NSAIDs or acetylsalicylic acid.
- Watch breathing and skin after the first dose for bronchospasm or anaphylaxis.
Pregnancy and breastfeeding
It is contraindicated in labour and delivery because it can affect the fetal circulation and inhibit uterine contractions; like other NSAIDs, it is avoided late in pregnancy.
Test yourself
Think of the answer, then tap the question to see it.
What is the maximum total duration of ketorolac treatment, and why?
Five days counting parenteral and oral use together, because the risk of ulcer, bleeding and kidney injury grows with duration.
Why is ketorolac contraindicated epidurally or intrathecally?
Because of the alcohol in the formulation.
What advantage does ketorolac have over an opioid after surgery, and what is the price?
Strong pain relief without respiratory depression or sedation, but it inhibits platelets and can cause bleeding, ulcers and kidney injury.
Why is hypovolaemia corrected before giving ketorolac?
Because in volume depletion the kidney depends on prostaglandins; ketorolac can precipitate acute renal failure.
Related drugs
← Back to the class: Nonsteroidal anti-inflammatory drugs (NSAIDs)
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Ketorolac: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); KETOROLAC TROMETHAMINE injection, solution (DailyMed (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 42 (McGraw Hill, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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