How do I write a PRN Voltaren (diclofenac) prescription?

How to Write a PRN Voltaren (Diclofenac) Order

For PRN (as-needed) diclofenac orders, write: "Diclofenac 50 mg PO every 8 hours PRN pain, maximum 150 mg/day" or "Diclofenac 75 mg IM every 12 hours PRN severe pain, maximum 150 mg/day." 1

Standard PRN Dosing Regimens

Oral PRN Orders

• Diclofenac 50 mg PO every 8 hours PRN pain (maximum 150 mg/24 hours) 1, 2
• Alternative: Diclofenac 25 mg PO every 6-8 hours PRN mild pain (maximum 150 mg/24 hours) 2
• For sustained-release formulations: Diclofenac 100 mg PO every 12 hours PRN (maximum 200 mg loading dose on day 1, then 150 mg/day maintenance) 2

Injectable PRN Orders (Intramuscular Preferred)

• Diclofenac 75 mg IM every 12 hours PRN severe pain (maximum 150 mg/24 hours, maximum 2 days duration) 1, 3
• The minimum interval between IM doses must be 12 hours to minimize adverse effects 1
• IM route is strongly preferred over IV for injectable diclofenac due to lower risk of dilution and dosing errors 1

IV Administration (Hospital Settings Only)

• Diclofenac 18.75-37.5 mg IV every 6 hours PRN postoperative pain (maximum 150 mg/24 hours) 1
• IV route should be reserved for severe cases unresponsive to IM administration or hospital settings with appropriate monitoring 1

Critical Dosing Limits

The absolute maximum daily dose is 150 mg by any route (oral, IM, or IV combined) 1, 4, 2. This is a hard ceiling—exceeding this dose significantly increases gastrointestinal and renal toxicity without additional analgesic benefit 1.

Essential Order Components

Every PRN diclofenac order must include:

• Specific dose (25 mg, 50 mg, or 75 mg) 1, 2
• Route (PO, IM, or IV) 1, 3
• Frequency/minimum interval (every 6-12 hours depending on formulation) 1, 2
• Indication ("for pain," "for acute pain," "for severe pain") 1
• Maximum daily dose (150 mg/24 hours) 1
• Maximum duration (especially for IM: 2 days maximum) 1, 3

Baseline Assessment Before First Dose

Before administering the first PRN dose, verify:

• No active peptic ulcer disease (absolute contraindication) 1
• No severe heart failure, liver failure, or history of GI bleeding (absolute contraindications) 1
• Baseline renal function (BUN, creatinine)—avoid if CrCl <10 mL/min 1
• Not taking anticoagulants (increases bleeding risk 3-6 fold) 1
• Age and GI risk factors (patients >60 years require gastroprotection with PPI) 1

Monitoring Requirements for PRN Use

Even for PRN orders, monitor:

• Blood pressure at baseline and with each administration (diclofenac can cause hypertension) 1
• Renal function (BUN, creatinine) if used for >2-3 doses 1
• Signs of GI bleeding (discontinue immediately if occurs) 1
• Fluid status and edema (diclofenac can cause fluid retention) 1

For chronic PRN use (>1 week), monitor every 3 months: blood pressure, BUN, creatinine, liver function tests, CBC, and fecal occult blood 1.

High-Risk Situations Requiring Extreme Caution or Avoidance

Avoid diclofenac PRN orders in patients with:

• Active peptic ulcer disease 1
• History of GI bleeding 1
• Concomitant anticoagulant use (warfarin, DOACs, aspirin) 1
• Pre-existing cardiovascular disease or heart failure 1
• Moderate-to-severe renal impairment (CrCl <30 mL/min) 1
• Compromised fluid status or concurrent nephrotoxic drugs 1

Use with extreme caution (add PPI) in patients:

• Age ≥60 years 1
• History of peptic ulcer disease 1
• Significant alcohol use 1

Common Pitfalls to Avoid

• Never write "diclofenac PRN" without specifying maximum daily dose—this can lead to overdosing beyond 150 mg/day 1
• Never combine diclofenac with other NSAIDs (ibuprofen, naproxen, ketorolac)—this increases GI bleeding and renal toxicity without added benefit 1
• Never prescribe IV diclofenac for outpatient use—serious adverse effects are attributed to IV overdoses 1
• Never exceed 2 days of IM diclofenac—prolonged IM use increases injection site complications 1, 3
• Never use PRN diclofenac in third trimester pregnancy 1

When to Discontinue PRN Diclofenac

Stop diclofenac immediately if:

• BUN or creatinine doubles from baseline 1
• Liver function tests increase to 3× upper limit of normal 1
• Any GI bleeding occurs 1
• New or worsening hypertension develops 1
• Signs of fluid overload or edema appear 1

Alternative Analgesic Strategy

If two different NSAIDs (including diclofenac) fail sequentially, switch to opioid analgesics or non-pharmacologic interventions rather than trying additional NSAIDs 1. Continuing to cycle through NSAIDs after two failures is futile and increases cumulative toxicity risk 1.