Fentanyl IV Infusion - Dose and Preparation

Available Formulation

Standard ampoule: 50 mcg/mL (available in 1, 2, 5, 10, 20, 50 mL vials)
Compatible diluents: Normal saline (0.9% NaCl) or 5% Dextrose
Stability: Diluted solution stable at room temperature for 24 hours

Dosing by Context

Adults - ICU / Mechanical Ventilation

Indication	Dose
Loading bolus	1-2 mcg/kg IV (25-100 mcg) over 5-10 min
Continuous infusion	0.7-10 mcg/kg/hr
Typical working range	1-3 mcg/kg/hr (most patients)
Intermittent PRN bolus	0.35-0.5 mcg/kg every 30-60 min (25-50 mcg)

(Source: UpToDate - Sedation in Ventilated Adults, SCCM guidelines)

Adults - IV-PCA (Patient-Controlled Analgesia)

Parameter	Dose
Demand dose	10-25 mcg per activation
Lockout interval	5-10 minutes
Background infusion (optional)	0.12-0.67 mcg/kg/hr

Pediatric Dosing (from Harriet Lane Handbook)

Age	Bolus	Continuous Infusion
Neonate / Young infant	1-4 mcg/kg/dose IV q2-4h (max 100 mcg)	1-5 mcg/kg/hr
Older infant and child	1-2 mcg/kg/dose IV/IM q30-60 min (max 100 mcg)	1-3 mcg/kg/hr (start at 1)

How to Prepare the Infusion

Standard Adult Concentrations

Concentration	Preparation (50 mL syringe)
10 mcg/mL	Draw 10 mL fentanyl (50 mcg/mL = 500 mcg) + 40 mL NS
20 mcg/mL	Draw 20 mL fentanyl (1000 mcg) + 30 mL NS
50 mcg/mL	Undiluted (use for concentrated infusions in fluid-restricted patients)

Infusion rate formula:

Rate (mL/hr) = Dose (mcg/kg/hr) x Weight (kg) / Concentration (mcg/mL)

Example: 70 kg patient, target dose 1 mcg/kg/hr, using 10 mcg/mL solution:

Rate = 1 x 70 / 10 = 7 mL/hr

Pediatric Preparation Formula (Harriet Lane Handbook)

$$50 \times \frac{\text{Desired dose (mcg/kg/hr)}}{\text{Desired infusion rate (mL/hr)}} \times \text{Weight (kg)} = \text{mcg Fentanyl in 50 mL fluid}$$

Example: 10 kg child, desired dose 1 mcg/kg/hr, desired rate 1 mL/hr:

50 × (1/1) × 10 = 500 mcg fentanyl in 50 mL (= 10 mcg/mL)

Neonatal Concentrations (by weight)

Neonate weight	Recommended concentration
< 1 kg	4 mcg/mL
1 to < 3 kg	10 mcg/mL
≥ 3 kg	20 mcg/mL

To make 4 mcg/mL (25 mL syringe): 2 mL fentanyl (100 mcg) + 23 mL NS To make 10 mcg/mL (25 mL): 5 mL fentanyl (100 mcg/2 mL stock) + 20 mL NS

Key Clinical Points

Point	Detail
Onset	IV: < 1-2 minutes; Duration: 30-60 min per dose
Lipophilicity	Highly lipophilic - accumulates with prolonged infusion (context-sensitive half-life increases significantly after hours of infusion)
Chest wall rigidity	Risk with rapid high-dose boluses; use naloxone/muscle relaxant if this occurs
Tolerance	Can develop rapidly, especially in neonates and prolonged ICU use
Renal/Hepatic impairment	Generally no major dose adjustment needed (metabolized by CYP3A4 to inactive metabolites)
ECMO	May require higher doses due to drug sequestration in circuit
Titrate to	Validated pain score (e.g., NRS, CPOT, FLACC in children)

Monitoring

Respiratory rate, SpO2, sedation score (e.g., RASS)
Pain score (NRS, CPOT)
Blood pressure and heart rate
Have naloxone (opioid reversal) readily available: 0.4-2 mg IV for adults; 0.01 mg/kg IV for children

Important safety note: Fentanyl is a high-alert medication. All preparations should be double-checked by a second clinician. Infusion rates should always be cross-verified using the weight-based formula. Titrate to the minimum effective dose using a structured analgesic protocol.

Calcukate dose for 60 kg fentanyl infusion 50mcg/ml in 50 ml seringe

Here is the complete calculated dose table for a 60 kg patient using fentanyl 50 mcg/mL in a 50 mL syringe (total = 2500 mcg fentanyl).

Setup

Parameter	Value
Patient weight	60 kg
Concentration	50 mcg/mL
Syringe volume	50 mL
Total drug in syringe	2500 mcg

Rate Formula

$$\text{Rate (mL/hr)} = \frac{\text{Dose (mcg/kg/hr)} \times \text{Weight (kg)}}{\text{Concentration (mcg/mL)}}$$

$$= \frac{\text{Dose} \times 60}{50}$$

Dose-to-Rate Table (60 kg, 50 mcg/mL)

Dose (mcg/kg/hr)	Calculation	Infusion Rate (mL/hr)	mcg/hr delivered
0.5	0.5 × 60 / 50	0.6 mL/hr	30 mcg/hr
1.0 (start here)	1.0 × 60 / 50	1.2 mL/hr	60 mcg/hr
1.5	1.5 × 60 / 50	1.8 mL/hr	90 mcg/hr
2.0	2.0 × 60 / 50	2.4 mL/hr	120 mcg/hr
2.5	2.5 × 60 / 50	3.0 mL/hr	150 mcg/hr
3.0	3.0 × 60 / 50	3.6 mL/hr	180 mcg/hr
4.0	4.0 × 60 / 50	4.8 mL/hr	240 mcg/hr
5.0	5.0 × 60 / 50	6.0 mL/hr	300 mcg/hr

Bolus Dose (PRN)

Indication	Dose	Volume to give
Standard bolus	1 mcg/kg = 60 mcg	1.2 mL IV over 5-10 min
Loading dose (ICU)	1-2 mcg/kg = 60-120 mcg	1.2 - 2.4 mL
Procedural bolus	2 mcg/kg = 120 mcg	2.4 mL

Syringe Duration at Common Rates

Rate	Duration of 50 mL syringe
1.2 mL/hr (1 mcg/kg/hr)	~41 hours
2.4 mL/hr (2 mcg/kg/hr)	~20 hours
3.6 mL/hr (3 mcg/kg/hr)	~14 hours

Quick Reference

Typical starting rate for ICU analgesia: 1.2 mL/hr (= 1 mcg/kg/hr)
Usual working range: 1.2 - 3.6 mL/hr (1-3 mcg/kg/hr)
Titrate up or down by 0.5 mcg/kg/hr increments (0.6 mL/hr steps) every 30-60 min based on pain score
Always double-check with a second nurse/clinician before starting infusion

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