Morphine Dose Calculation
A patient taking 0.25 mL of morphine concentrate 20 mg/mL is receiving 5 mg of morphine per dose.
Calculation Method
The dose calculation follows a straightforward formula used universally in clinical practice:
- Dose (mg) = Volume (mL) × Concentration (mg/mL) 1
- For this patient: 0.25 mL × 20 mg/mL = 5 mg of morphine 1
Clinical Context for This Dose
Appropriateness for Opioid-Naïve Patients
- 5 mg represents a conservative starting dose for opioid-naïve patients with moderate pain, falling within the recommended range of 5-10 mg orally every 4 hours 2
- This dose aligns with the low-dose morphine approach that has demonstrated excellent tolerability with minimal discontinuation rates (<10%) in opioid-naïve cancer patients 3
Dose Range Perspective
- Studies demonstrate morphine is effective across a wide dose range from 25 mg to 2000 mg daily, with average doses between 100-250 mg per day 4
- A single 5 mg dose represents a modest starting point that allows for safe upward titration based on pain response 3, 2
Important Clinical Considerations
Titration Principles
- If this 5 mg dose provides inadequate pain relief, increase the dose rather than shortening the dosing interval 2
- Breakthrough doses should equal the regular scheduled dose (another 5 mg in this case), available every 1-2 hours as needed 2
- Review total daily morphine consumption every 24 hours and adjust the regular dose accordingly 2
Common Pitfall to Avoid
- Do not assume liquid morphine concentrations are standardized—always verify the concentration on the label before calculating doses, as morphine concentrates come in various strengths (commonly 20 mg/mL, but also 10 mg/mL, 30 mg/mL, and others) 1
- Concentration errors represent a high-risk medication safety issue that can lead to significant overdose or underdose 1