Medication Math, Standard Infusion Concentrations and Drip Rates

The five infusions below are the ones EMS, ED and ICU teams program most. Each row lists the label dilution or premixed bag, and the label starting dose. Doses vary by protocol; follow local protocols and medical direction. Not covered here: epinephrine, nitroglycerin, heparin and insulin infusions.

1. Match the bag to the pump entry. Read the product label: the drug, the concentration in mcg/mL or units/mL, and the volume. Pick the pump entry for that exact concentration.
2. Identify the dose basis. Weight-based drips are in mcg/kg/min (dopamine, dobutamine). Fixed drips are in mcg/min, units/min or mg/min (norepinephrine, vasopressin, amiodarone). Record the dosing weight the order uses (actual, ideal or lean, per protocol).
3. Convert the order to mL/hr. Use the formulas in Calculations & Formulas, then check the answer against the worked examples in Additional Tables.
4. Check the rate on the pump. Confirm the drug, concentration, dose unit and mL/hr on the screen before the drip starts, and again at every bag change and handoff.
5. Titrate in the stated steps. Re-check the perfusion picture after each change, not only the number on the monitor.

Choosing the agent for shock is covered in Vasopressors and Inotropes: Receptor and Selection Guide.

Worked Rate Conversions (70 kg Adult)

Every row comes from the formulas below. Weight-based rows assume 70 kg. Fixed-rate rows ignore weight. The 16 mcg/mL and 2,000 mcg/mL rows are example concentrations, not label products. Check every number against the order and the bag.

Drip Rate in gtt/min at 100 mL/hr

gtt/min = mL/hr × drop factor ÷ 60. Drop factors vary by manufacturer, so read the number printed on the tubing package. The values below are typical examples only.

Example: 1 mg from a vial of 1 mg/10 mL (0.1 mg/mL) is 1 ÷ 0.1 = 10 mL. Convert mcg to mg first. 500 mcg is 0.5 mg, so 0.5 mg from that same vial is 5 mL. The vial label sets the concentration, and products differ, so read it every time.

Example: 4 mg in 1,000 mL is 4,000 mcg ÷ 1,000 mL = 4 mcg/mL. Convert mg to mcg first, since 1 mg = 1,000 mcg.

Example: dopamine at 5 mcg/kg/min for an 80 kg patient on 1,600 mcg/mL. 5 × 80 × 60 = 24,000 ÷ 1,600 = 15 mL/hr.

Example: norepinephrine at 8 mcg/min on a 4 mcg/mL bag. 8 × 60 = 480 ÷ 4 = 120 mL/hr. That same dose on a 16 mcg/mL bag runs at 30 mL/hr. The concentration sets the rate, so check it before you trust the number.

Example: 0.1 mcg/kg/min for an 80 kg patient on 4 mcg/mL. 0.1 × 80 × 60 = 480 ÷ 4 = 120 mL/hr, the same rate as 8 mcg/min on this bag. The arithmetic does not change. Protocol sets the starting dose. The Levophed label lists mcg/min only, so confirm which unit your protocol and pump library use.

Example: 100 mL/hr on a 15 gtt/mL set is 100 × 15 ÷ 60 = 25 gtt/min. Round to the nearest whole drop only when the protocol allows it.

• Pediatrics: Infusion doses here are weight-based, and the pediatric protocol sets them. Start with Weight-Based Dosing. Dopamine label: 2–5 mcg/kg/min starting dose for adults and pediatric patients. Dobutamine label: the premixed container system may not suit patients under 30 kg. Norepinephrine and vasopressin labels: pediatric safety and effectiveness have not been established. Amiodarone label: the same gap exists. In a 61-patient pediatric trial, hypotension, bradycardia and AV block were common.
• Pregnancy: Vasopressin label: clearance rises in the second and third trimester. The dose may need to go up, and the drug may cause uterine contractions. Amiodarone label: can cause fetal harm. Tell the patient about that risk if the drug is given or pregnancy occurs. Norepinephrine label: a high-dose study in pregnant sheep showed reduced placental blood flow. Dopamine and dobutamine: follow the drug page and local obstetric protocol.
• Older Adults: Vasopressin label: usually start at the low end of the dosing range. These labels give the other infusions no age-specific adjustment. Start low and titrate to the response.
• Hepatic Impairment: Amiodarone label: acute hepatocellular necrosis has been reported with IV amiodarone. Watch for progressive hepatic injury. If it occurs, consider reducing the rate or stopping the infusion.

• Error: mcg/min keyed as mcg/kg/min, or the reverse. At 80 kg, 5 mcg/kg/min is 400 mcg/min. Confirm the unit on the order and on the pump.
• Error: Wrong bag or wrong drug in the pump library. Dopamine and dobutamine premixes come in several strengths, and a 2- to 4-fold rate error is possible. The names look alike. Read the full name and the concentration off the bag label.
• Error: Pounds entered where kilograms are needed. 1 kg = 2.2 lb. Keying 176 lb as 176 kg makes a weight-based drip 2.2 times too fast. Put the weight in kg on the pump.
• Error: Vasopressin units/min and units/hr confused. The Vasostrict label doses in units/min, and 0.03 units/min = 1.8 units/hr. Running a units/hr value as units/min is a 60-fold overdose. Entering a units/min value as units/hr is a 60-fold underdose.
• Error: Starting a dopamine drip with hypovolemia, acidosis or hypoxia still uncorrected. The dopamine label says to fix these before the drip starts.
• Error: Vasoactive drip through a small or unsecured line. If norepinephrine or dopamine infiltrates, it can cause tissue necrosis. Use a large vein or a central line. Check the site often and follow the extravasation protocol. Levophed label: infiltrate with 5–10 mg phentolamine in 10–15 mL saline (adults), ideally within 12 hours. Nexterone label: give it through a dedicated central line when possible, with an in-line filter.
• Error: Stopping a vasopressor drip abruptly. The Levophed and dopamine labels say to wean the rate gradually while volume is expanded. The Vasostrict label says to taper vasopressin by 0.005 units/min every hour once target pressure has held for 8 hours.
• Error: Amiodarone total not tracked. Keep a running 24-hour amiodarone total, boluses and supplemental doses included. In label trials, mean daily doses above 2,100 mg were linked to hypotension. That is a trial average, not a dose limit.

• Premixed bags: One drug can come in several concentrations. Read the bag, not the drug name, and enter the concentration on the pump before the rate. This varies by state and agency protocol.
• Concentrate only: If concentrate is all you carry, mix it per agency protocol. Label the bag with the drug, the concentration and the time. Then recheck the rate against this page.
• Handoff: State the drug, the concentration, the rate in mL/hr, the dose in mcg/kg/min or units/min, and the dosing weight.