Author:
Kai Knudsen
Updated:
23 December, 2025
Here you will find recommended therapeutic serum concentrations for a range of medications used in intensive care. The tables present the medications sorted by both generic names and brand names.
Essential Conversions & Core Formulas
Weight & Length
Weight:
• 1 kg = 2.2 lb
• 1 lb = 0.45 kg
Length:
• 1 inch = 2.54 cm
• 1 cm = 0.39 inch
• Quick reference: 6 ft ≈ 183 cm, 5 ft ≈ 152 cm
Temperature
• °F = (°C × 1.8) + 32
• °C = (°F − 32) ÷ 1.8
• Normal: 37 °C (98.6 °F)
• Hypothermia: < 36 °C
Pressure Conversions
• 1 atm = 760 mmHg = 101 kPa
• 1 mmHg = 1.36 cmH₂O
• 1 cmH₂O = 0.74 mmHg
• 1 kPa = 7.5 mmHg
• 1 bar = 750 mmHg
• PEEP 5 cmH₂O ≈ 3.7 mmHg
Volume & Concentration
Volume:
• 1 L = 1000 mL
• 1 mL = 1 cc
Concentration:
• % solution = (% × 10) mg/mL
• 1% = 10 mg/mL
• 0.5% = 5 mg/mL
• 1000 mcg = 1 mg
• 1 mL/kg crystalloid ≈ 1% change in hemoglobin
Infusion Rate Calculations
mcg/kg/min → mL/hr:
Rate = (Dose × Weight (kg) × 60) ÷ Concentration (mcg/mL)
mg/hr → mL/hr:
Rate = Dose (mg/hr) ÷ Concentration (mg/mL)
Units/hr → mL/hr:
Rate = Units/hr ÷ Concentration (units/mL)
Standard Infusion Strengths (verify local protocols)
Vasopressors:
• Epinephrine 1:1000 = 1 mg/mL
• Epinephrine 1:10,000 = 0.1 mg/mL
• Phenylephrine 100 mg/100 mL = 1000 mcg/mL
• Norepinephrine 4 mg/250 mL = 16 mcg/mL
• Vasopressin 20 units/100 mL = 0.2 units/mL
• Dopamine 400 mg/250 mL = 1600 mcg/mL
• Ephedrine 50 mg/10 mL = 5 mg/mL
Hemodynamic Calculations
Mean Arterial Pressure (MAP):
MAP = (SBP + 2 × DBP) ÷ 3
Systemic Vascular Resistance (SVR):
SVR = ((MAP − CVP) ÷ CO) × 80
Normal: 800–1200 dyn·s/cm⁵
Pulmonary Vascular Resistance (PVR):
PVR = ((MPAP − PCWP) ÷ CO) × 80
Normal: 20–120 dyn·s/cm⁵
Cardiac Index (CI):
CI = CO ÷ BSA (Normal: 2.5–4.0 L/min/m²)
Oxygenation Formulas
Oxygen Content (CaO₂):
CaO₂ = (1.34 × Hgb × SaO₂) + (0.003 × PaO₂)
Oxygen Delivery (DO₂):
DO₂ = CO × CaO₂ × 10
Normal: ~520–720 mL/min/m²
A–a Gradient:
A–a = [(FiO₂ × 713) − (PaCO₂ ÷ 0.8)] − PaO₂
Normal: <10–15 mmHg on room air
P/F Ratio:
PaO₂ / FiO₂
ARDS: <300, Severe: <100
Local Anesthetic Concentrations
Lidocaine:
• 0.5% = 5 mg/mL
• 1% = 10 mg/mL
• 2% = 20 mg/mL
Bupivacaine:
• 0.25% = 2.5 mg/mL
• 0.5% = 5 mg/mL
Ropivacaine:
• 0.2% = 2 mg/mL
• 0.5% = 5 mg/mL
Local Anesthetic Maximum Doses
• Lidocaine: 4.5 mg/kg (max 7 mg/kg with epinephrine)
• Bupivacaine: 2.5 mg/kg (max 3 mg/kg with epinephrine)
• Ropivacaine: 3 mg/kg
Monitor for LAST – lipid emulsion 20% as rescue therapy
Therapeutic Drug Concentrations
| Drugs | Label Name | Specimen | Reference values in Serum |
|---|---|---|---|
| Amitriptyline | Saroten, Tryptizol | S-: | 300-700 nmol/L |
| Amlodipine | Amlodipin, Norvasc | S-: | 0,025 mg/L |
| Atenolol | Atenolol, Tenormin | S-: | 0,54 mg/L |
| Carbamazepine | Tegretol, Hermolepsin | S-: | 20-40 µmol/L |
| Citalopram | Citalopram, Cipralex. | S-: | 20-800 nmol/L |
| Digoxin | Lanacrist | S-: | <1,4 nmol/L |
| Phenytoin | Epanutin | S-: | 40-80 µmol/L |
| Flecainide | Tambocor | S-: | 0,5-2,0 µmol/L |
| Fluoxetin | Fontex | S-: | 100-1940 nmol/L |
| Gentamicin | Gentamicin, Garamycin | S-: | 1.5-4.0 mg/L 8 hours after administration. |
| Clomipramin | Anafranil | S-: | 550-1300 nmol/L (Clomipramin + desmetylklomipramin) |
| Clonazepam | Iktorivil | S-: | 35-60-(120) µmol/L |
| Litium | Lithionit | S-: | 0,5 -0,8 mmol/L, sometimes 0,9-1,2 mmol/L |
| Lamotrigin | Lamictal | P-: | 12-56 µmol/L |
| Levetiracetam | Keppra | P-: | 35-120 µmol/L |
| Meropenemanhydrat | Meronem | S-: | 8-10 µg/mL |
| Mirtazapin | Mirtazapin, Remeron | S-: | 35-520 nmol/L |
| Olanzapin | Olanzapine, Zyprexa | S-: | 15-300 nmol/L |
| Oxazepam | Oxazepam, Oxascand | S-: | 0,7-4,2 µmol/L. |
| Paracetamol | Alvedon, Panodil, Reliv | S-: | Reference value not detectable. In case of intoxication, sampling, interpretation of test results and treatment should be in accordance with the Poison Information Center's guidelines. |
| Paroxetine | Paroxetine, Seroxat | S-: | 20-600 nmol/L |
| Propranolol | Propranolol, Inderal | S-: | 0,075-0,1 mg/L |
| Quetiapine | Seroquel | S-: | 50-700 nmol/L |
| Risperidon | Risperidone, Risperdal | S-: | 50-150 nmol/L |
| Salicylates | Trombyl, Treo, Magnecyl, Bamyl, Aspirine | S-: | 1,1-2,2 mmol/L (Adults) |
| Sertraline | Sertraline, Seroxat | S-: | 10-525 nmol/L |
| Tacrolimus | Prograf | B-: | 5-20 µg/L |
| Theophylline | Theophylline, Theo-Dur | S-: | 55-110 µmol/L |
| Tobramycin | Nebcin | S-: | The lowest value should not exceed 2 mg/L. In a test taken 1 hour after initiation of administration, the concentration should be at least 4 mg/L and not more than 12 mg/L. |
| Topiramat | Topimax | S-: | 15-60 µmol/L. |
| Valproate | Ergenyl | S-: | 350-700 µmol/L |
| Vancomycine | Vancocin | S-: | The lowest value should not exceed 15 mg/L. Samples taken 1 hour after completion of infusion should not exceed 50 mg/L. |
| Venlafaxine | Efexor | S-: | 50-900 nmol/L |
| Zuclopentixol | Cisordinol | S-: | 7-30 nmol/L |
