ICU pharmacology and drug infusions

Use one standard concentration per drug across the ICU, label the final concentration, and convert doses to mL/h with a single formula: rate (mL/h) = dose (mcg/kg/min) × weight (kg) × 60 ÷ concentration (mcg/mL). Double-check every high-alert infusion.

Pick the dosing weight per drug: lipophilic loading doses and some antimicrobials by actual weight, most maintenance infusions and neuromuscular blockers by ideal or adjusted weight, and titrate sedatives to effect. Use therapeutic drug monitoring where available.

Never reduce loading doses for renal function. Adjust maintenance doses to measured or estimated clearance, recognising that creatinine is unreliable in unstable AKI, that CRRT removes many antibiotics, and that young septic or trauma patients often clear drugs faster than normal.

No liver test predicts drug clearance well. In cirrhosis and acute liver failure prefer drugs with short half-lives or non-hepatic elimination, avoid long-acting sedatives, lower and titrate high-extraction and highly protein-bound drugs, and watch for encephalopathy and bleeding.

Stack-check QT drugs and risk factors (low K/Mg, bradycardia, female sex, structural heart disease). Stop offending drugs when QTc exceeds 500 ms or rises more than 60 ms, give IV magnesium for torsades, and watch the handful of interactions that cause real ICU harm.

Give vasoactives through a dedicated labelled lumen, never Y-site unknown combinations, keep blood, parenteral nutrition and bicarbonate separate, and recognise extravasation early. Peripheral vasopressors are acceptable short-term with a good proximal vein, hourly checks and an extravasation plan.