Quick cards
Equivalents and Conversions
Opioid, steroid and benzodiazepine equivalence; units that trip people up
Opioid equianalgesic doses
| Morphine | 10 mg IV = 30 mg PO |
|---|---|
| Hydromorphone | 1.5 mg IV = 7.5 mg PO |
| Fentanyl | 100 mcg IV (patch: 25 mcg/h ≈ morphine 60–90 mg PO/day) |
| Oxycodone | 20 mg PO |
| Hydrocodone | 30 mg PO |
| Methadone | Non-linear; specialist conversion |
| Tramadol | About 100–120 mg PO (weak; ceiling 400 mg/day) |
When switching drugs, reduce the calculated dose by 25–50% for incomplete cross-tolerance, then titrate.
Corticosteroid equivalence
| Hydrocortisone | 20 mg (short-acting; strong mineralocorticoid effect) |
|---|---|
| Cortisone | 25 mg |
| Prednisone / prednisolone | 5 mg |
| Methylprednisolone | 4 mg (little mineralocorticoid effect) |
| Dexamethasone | 0.75 mg (long-acting; no mineralocorticoid effect) |
Stress dosing for a patient on long-term steroids: hydrocortisone 50–100 mg IV, then 50 mg every 6–8 h, tapering as the illness settles.
Benzodiazepine equivalence
| Lorazepam | 1 mg (IV onset 5–10 min; no active metabolites) |
|---|---|
| Midazolam | 2 mg IV (fast, short; accumulates in infusion) |
| Diazepam | 5 mg (fast IV onset; long active metabolites) |
| Alprazolam | 0.5 mg PO |
| Clonazepam | 0.5 mg PO |
| Chlordiazepoxide | 25 mg PO |
Equivalence tables vary; use them to start, then dose to the RASS or CIWA target.
Unit conversions
Pressure
| 1 mmHg | 1.36 cm H₂O = 0.133 kPa |
|---|---|
| 1 cm H₂O | 0.74 mmHg |
| 1 kPa | 7.5 mmHg |
| 1 atm | 760 mmHg = 1,033 cm H₂O = 14.7 psi |
Labs
| Glucose | mg/dL ÷ 18 = mmol/L (180 mg/dL = 10 mmol/L) |
|---|---|
| Creatinine | mg/dL × 88.4 = µmol/L |
| Calcium (total) | mg/dL ÷ 4 = mmol/L; ionized 1.1–1.3 mmol/L = 4.4–5.2 mg/dL |
| Magnesium | 1 mEq/L = 0.5 mmol/L = 1.2 mg/dL |
| Bilirubin | mg/dL × 17.1 = µmol/L |
| Lactate | mmol/L × 9 = mg/dL |
Mass and volume
| 1 g | 1,000 mg = 1,000,000 mcg |
|---|---|
| 1 mg | 1,000 mcg = 1,000,000 ng |
| 1 kg | 2.2 lb; 1 lb = 454 g |
| 1 grain | 65 mg (nitroglycerin 1/150 gr = 0.4 mg) |
| 1 oz | 30 mL; 1 tsp = 5 mL; 1 tbsp = 15 mL |
| °F to °C | (°F − 32) × 5/9; 100.4 °F = 38 °C |
Electrolyte salts
| KCl | 1 mEq = 75 mg; 20 mEq in 100 mL over 1 h is a typical IV limit |
|---|---|
| NaCl 0.9% | 154 mEq/L sodium; 3%: 513 mEq/L |
| Sodium bicarbonate 8.4% | 1 mEq/mL |
| Calcium gluconate 10% | 1 g = 4.65 mEq (93 mg) elemental calcium |
| Calcium chloride 10% | 1 g = 13.6 mEq (272 mg) elemental calcium |
| Magnesium sulfate | 1 g = 8.1 mEq |
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For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow your local protocols and medical direction.