IbuprofenPA study guide

Mechanism

A nonselective NSAID. Its mode of action is not completely understood but is probably related to inhibiting prostaglandin synthesis, giving analgesic, antipyretic, and anti-inflammatory effects. In primary dysmenorrhea it lowers prostaglandin activity in menstrual fluid and reduces uterine pressure and contraction frequency. It inhibits platelet aggregation less than aspirin, and the effect is reversible and short.

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Why they happen and how to manage them

GI ulcers and bleeding

Loss of protective prostaglandins in the gastric mucosa, plus reduced platelet function. Management: Lowest dose for the shortest time; take with food; consider a PPI in high-risk patients; stop if bleeding occurs.

Kidney injury

Blocking renal prostaglandins reduces renal blood flow in patients who depend on them. Management: Avoid in advanced kidney disease and dehydration; monitor creatinine with diuretics or ACE inhibitors.

Hypertension and edema

Prostaglandin inhibition causes sodium and fluid retention. Management: Monitor blood pressure, especially at the start.

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Common and serious

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Narrow therapeutic index

The label does not describe a narrow therapeutic index or direct dosing by measured blood levels of the drug.

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ALT (liver enzyme)

Why

Hepatic reactions

When

When symptoms or signs suggest liver dysfunction

Act on

Stop if liver disease develops

Normal

4 to 36 U/L.

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Blood pressure

Why

New or worsening hypertension

When

Closely at the start of treatment and throughout

Normal

Below 120/80 mm Hg.

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Serum creatinine

Why

Renal decompensation, especially with diuretics, ACE inhibitors, heart failure, or older age

When

Closely if it must be used in advanced renal disease

Normal

0.7 to 1.3 mg/dL in men and 0.5 to 0.95 mg/dL in women.

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Adult dose

Rheumatoid arthritis and osteoarthritis

1200 to 3200 mg daily, as 400, 600, or 800 mg three or four times a day.

Mild to moderate pain

400 mg every 4 to 6 hours as needed; higher single doses were no more effective.

Primary dysmenorrhea

400 mg every 4 hours as needed, starting at the earliest onset of pain.

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Renal adjustment

Not recommended in advanced renal disease; if it must be used, monitor renal function closely. Impaired renal function, heart failure, liver dysfunction, diuretics, ACE inhibitors, and older age raise the risk of renal decompensation.

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Hepatic adjustment

No labeled dose change. Borderline liver test rises are common, and rare severe hepatic reactions occur; stop if signs of liver disease develop.

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Boxed warning

Cardiovascular thrombotic events: NSAIDs raise the risk of serious, possibly fatal heart attack and stroke, which may start early in treatment and grow with longer use; contraindicated around CABG surgery. Gastrointestinal risk: NSAIDs raise the risk of serious, possibly fatal GI bleeding, ulcers, and perforation, which can occur at any time without warning; older adults are at greater risk.

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Contraindications

• Known hypersensitivity to ibuprofen
• Asthma, urticaria, or allergic-type reactions after aspirin or other NSAIDs
• Setting of coronary artery bypass graft (CABG) surgery

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Key interactions

Low-dose aspirin

Interferes with aspirin's antiplatelet effect, especially when ibuprofen is taken first. Together they also raise GI bleeding risk.

Warfarin and other anticoagulants

Synergistic GI bleeding risk.

ACE inhibitors, ARBs, and diuretics

Blunt their blood pressure and diuretic effects and raise the risk of kidney injury.

Lithium

Raises lithium levels and lowers its renal clearance. Watch for lithium toxicity.

Methotrexate

May increase methotrexate toxicity.

Corticosteroids, SSRIs, SNRIs

Raise the risk of GI ulcers and bleeding.

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Antidote or reversal

No specific antidote. Overdose care is supportive; because the drug is acidic and excreted in urine, alkaline diuresis may help in theory.

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Pregnancy

Limit dose and duration from about 20 to 30 weeks, and avoid from about 30 weeks on. From about 20 weeks, NSAIDs can impair fetal kidney function and cause low amniotic fluid; from about 30 weeks, they can close the fetal ductus arteriosus early.

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Lactation

Not known whether it is excreted in milk. Decide whether to stop nursing or stop the drug, based on its importance to the mother.

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Pediatric

Safety and effectiveness of these prescription tablets in children have not been established.

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Geriatric

Use with caution at 65 and older. Older adults have a greater risk of serious GI events and renal decompensation.

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