Clinical beta

FMBM is currently in clinical beta. Content is for professional review/testing and must not replace local protocols, senior clinical judgment, or official prescribing references.

Drug Monograph

Diclofenac

USE IF: Acute pain (diclofenac K), renal colic IM, postoperative pain, OA/RA (short-term), topical OA

AVOID IF: IHD/CHF/PAD/stroke, eGFR <30, active GI bleed, pregnancy >=20 weeks, AERD

Diclofenac (Sodium / Potassium)

Non-selective NSAID (preferential COX-2)

NSAIDAcute painRenal colicHigh CV riskHepatotoxic

Indication

Acute pain, renal colic IM, OA/RA (short-term), postoperative pain

At a glance

INDICATION -> Acute pain (diclofenac K), renal colic (IM), postoperative pain, OA/RA (short-term)

ADULT DOSE -> 50 mg PO TID (diclofenac K); 75 mg IM stat

MAX DOSE -> 150 mg/day TOTAL (all routes combined)

CONTRA -> IHD/CHF/PAD/stroke; active GI bleed; eGFR <30; pregnancy >=20 weeks

ANTIDOTE -> No specific; supportive care only

Quick facts

Onset

30–60 min (K); 1–2 h (Na EC)

Duration

Peak 30–60 min (K); 2–4 h (Na). Duration: 6–8 h (IR), up to 12 h (SR). t1/2 1–2 h.

Routes

PO, IM, PR, topical; IV restricted

Pregnancy

Avoid >=20 weeks; contraindicated >=30 weeks

Renal

Avoid if eGFR <30

Hepatic

Avoid severe impairment

Do not miss

Time to action: 30—60 min (K); 2—4 h (EC sodium)

Max dose

  • 150 mg/day TOTAL (oral + IM + PR combined).
  • Includes ALL formulations (PO + IM + PR combined).
  • Exceeding dose significantly increases CV and hepatic risk.

Black box risks

  • Higher risk vs other NSAIDs.
  • Monitor LFTs at baseline and periodically (4–8 weeks).
  • Stop if ALT/AST >3× ULN or symptomatic.
  • DOSE DURATION: Risk increases with duration -> avoid prolonged use whenever possible.
  • GI bleeding risk (may occur any time).
  • Severe skin reactions (SJS/TEN) and NSAID-sensitive bronchospasm.

No specific antidote

  • No specific antidote — supportive care only.

High-risk scenarios

  • Highest CV risk among NSAIDs (similar to COX-2 inhibitors).
  • Avoid in: established CAD / stroke; high CV-risk patients.
  • Use alternatives (naproxen preferred if NSAID required).
  • Triple whammy risk is high with ACEi/diuretics + NSAID.

Key interactions

  • Warfarin/NOACs -> increased bleeding.
  • Methotrexate -> increased toxicity.
  • Lithium -> increased levels.
  • ACEi/ARB + diuretics -> AKI (triple whammy).
  • Cyclosporine/tacrolimus -> nephrotoxicity.

Indications

Primary

  • Acute pain
  • Renal colic (diclofenac K/IM)
  • Dysmenorrhea
  • OA/RA (short-term)

Secondary

  • Gout
  • Migraine (K salt)
  • Postoperative pain

Other

  • Post-ERCP pancreatitis prevention (PR)
  • Topical OA

Dosing

Standard: 50 mg TID PO (K) or 75 mg IM stat

Max daily dose

  • 150 mg/day total (all routes combined).

Adult - PO

  • ACUTE PAIN: 50 mg TID (K salt).
  • OA / RA: 75–150 mg/day divided.
  • DYSMENORRHEA: 50 mg TID (start early).
  • TOPICAL OA: Gel preferred (lower systemic risk).
  • NOTE: Always consider topical before oral in OA.

Adult - IV

  • Dyloject: 37.5 mg IV q6h (hospital use).

Pediatric

  • 1–3 mg/kg/day divided (specialist only).

Renal adjustment

  • eGFR >=30: caution.
  • eGFR <30: avoid.

Hepatic adjustment

  • Mild: monitor LFTs.
  • Severe: avoid.

Warnings

Clinical warnings

  • Highest CV risk among NSAIDs (EMA coxib-equivalent).
  • GI bleeding risk (may occur any time).
  • Hepatotoxicity (most among NSAIDs).
  • AKI risk (especially triple whammy).
  • Fluid retention and HF exacerbation.
  • Severe skin reactions (SJS/TEN).
  • Bronchospasm in NSAID-sensitive asthma.

Adverse effects

  • Common: GI upset, dyspepsia, nausea, edema.
  • Serious: GI bleed, hepatotoxicity, CV events, SJS/TEN.

Contraindications / caution

Do not use

  • IHD, CHF, PAD, stroke (EMA absolute).
  • Established cardiovascular disease (avoid if possible).
  • Active GI bleeding.
  • eGFR <30.
  • Severe liver disease.
  • Pregnancy >=30 weeks.
  • CABG perioperative.

Use caution / avoid high doses

  • Elderly.
  • CKD (30–60).
  • Hypertension.
  • Anticoagulants.
  • Liver disease.

Drug interactions

  • Warfarin/NOACs -> increased bleeding.
  • Methotrexate -> increased toxicity.
  • Lithium -> increased levels.
  • ACEi/ARB + diuretics -> AKI (triple whammy).
  • Cyclosporine/tacrolimus -> nephrotoxicity.

Special populations

Pediatrics

1–3 mg/kg/day divided (specialist only).

Pregnancy

Avoid >=20 weeks; contraindicated >=30 weeks.

Breastfeeding

Not preferred (ibuprofen often safer).

Elderly

Avoid systemic use if possible; prefer topical.

Liver disease

High hepatotoxicity risk -> avoid severe disease.

Renal impairment

Avoid if eGFR <30.

Administration

  • Route: PO (diclofenac K for acute), IM (deep gluteal, e.g., renal colic), PR, topical.
  • IV: Dyloject hospital use; Voltarol/others may require infusion per local protocol.
  • Do NOT use EC sodium for acute pain.
  • Ensure adequate hydration before IV use -> reduces AKI risk.

Infusion / dilution

  • Voltarol ampoule: infusion only (e.g., 30–120 min) per product protocol.

Monitoring

  • LFTs: baseline, 4–8–12 weeks (depending on risk).
  • Renal function.
  • INR if on warfarin.
  • Lithium levels (if relevant).
  • BP.
  • GI bleeding.
  • Edema.
  • Hepatic symptoms.

Overdose / toxicity

IF SUSPECTED DICLOFENAC OVERDOSE: • Assess ABC, check renal function, electrolytes, ABG • Consider activated charcoal within 1–2 hours if protected airway • Monitor for CNS depression, AKI, metabolic acidosis ESCALATE: • Severe acidosis • Persistent CNS depression • Renal failure NOTE: Dialysis NOT effective for drug removal (only for severe AKI/acidosis)

Recognition

  • <100 mg/kg → mild
  • 100–400 mg/kg → moderate toxicity
  • >400 mg/kg → severe risk (CNS, renal, acidosis)
  • FORMULATION DIFFERENCE: diclofenac K = faster onset (acute pain); diclofenac Na = slower onset (chronic use); wrong formulation is a common prescribing error.

Immediate actions

  • Activated charcoal (when within <=2 h).
  • IV fluids.
  • Treat complications (e.g., acidosis, seizures) supportively.

Antidote

  • No specific antidote — supportive care.

Decontamination

  • Activated charcoal (<=2 h) if appropriate and airway protected.

Escalation

  • Severe acidosis.
  • Persistent CNS depression.
  • Renal failure.
  • NOTE: Dialysis NOT effective for drug removal (only for severe AKI/acidosis).

Clinical pearls

Common mistakes, resistance logic, and bedside traps

CV safety

  • Highest CV risk NSAID -> avoid in any CV disease.
  • Diclofenac = higher CV + hepatic risk.
  • Use naproxen if NSAID needed in CV-risk patients.

Formulation timing

  • Diclofenac K = fast; Na EC = slow (common error).

Dose limits

  • Max dose includes ALL routes combined (oral + IM + PR).

Liver monitoring

  • Most hepatotoxic NSAID -> monitor LFTs.

Renal colic + IV safety

  • IM diclofenac = first-line for renal colic.
  • Dyloject != Voltarol (IV safety critical).

Elderly + triple whammy

  • Prefer topical in elderly.
  • Triple whammy risk is high.

TOPICAL FIRST

  • Prefer topical diclofenac for OA (especially elderly).
  • Similar efficacy for localized pain with lower systemic risk.

Pharmacokinetics

  • Bioavailability ~50–60%.
  • Highly protein bound (>99%).
  • Hepatic metabolism (CYP2C9).
  • Renal + biliary elimination.
  • Short plasma half-life -> frequent dosing.

Mechanism of action

  • Reversible COX inhibition (COX-2 > COX-1).
  • Decreased prostaglandins -> decreased pain/inflammation.
  • Additional anti-inflammatory pathways.

Common brand names

Saudi Arabia

Voltaren · Cataflam · Voltfast · Clofen (Julphar) · Rapidus

Global

Dyloject · Cambiya · Zipsor · Arthrotec

Common trade names are curated examples only — formulations and availability vary. Verify the exact product name with your local pharmacy and national regulator before prescribing or dispensing.

Country practice notes

  • Widely used in Gulf for renal colic (75 mg IM).
  • High CV risk -> avoid in common Gulf population (diabetes/CVD prevalence).
  • Potassium salts (Voltfast, Rapidus) preferred for acute pain.
  • Topical diclofenac widely used in elderly OA (safer alternative).
  • Multiple regional brands (Voltaren, Cataflam, Clofen, Rapidus).

Saudi Arabia — confirm with local formulary.