Pulmonary, obstetric and electrolyte infusions
Terbutaline (Brethine) drip
Brethine, Bricanyl
Dosing
| Start | Severe asthma when inhaled drug cannot get in: 0.25 mg SC in the lateral deltoid, once more in 15–30 minutes, max 0.5 mg in 4 hours (label; EPR-3 allows every 20 minutes × 3). IV infusion (off-label in the US, not routine in adults): 1.5–5 mcg/min (UK label) |
|---|---|
| Titrate | By bronchospasm, heart rate and K. Preterm labor (UK label): 5 mcg/min, up 2.5 every 20 minutes until contractions stop; hold 1 hour, then down 2.5 every 20 minutes to the lowest rate that works |
| Maximum | Asthma: 5 mcg/min (UK label). Tocolysis: rarely over 10 and never over 20 mcg/min, for no more than 48 hours (UK label). Boxed warning: no injectable terbutaline for tocolysis beyond 48–72 hours |
| Common bags | 2.5 mg in 500 mL (5 mcg/mL); 5 mg in 500 mL (10 mcg/mL); 5 mg in 50 mL (100 mcg/mL) |
| Dose units | mcg/min |
Line and administration
- UK label dilutions: asthma 1.5–2.5 mg in 500 mL (3–5 mcg/mL); preterm labor 5 mg in 500 mL (10 mcg/mL), or 5 mg in 50 mL (100 mcg/mL) by syringe pump, in 5% dextrose (saline adds pulmonary edema risk). US vials are 1 mg/mL
- Peripheral or central
Watch for
- Tachycardia, arrhythmias and myocardial ischemia
- Low K, high glucose and lactic acidosis (which can look like worsening asthma)
- Pregnancy: keep maternal heart rate at 120 or less (UK label); maternal pulmonary edema and deaths, fetal tachycardia, newborn hypoglycemia
Terbutaline: full drug monographIndications, mechanism, pharmacokinetics, cautions and every dose the app lists.
In the one-pagers
- Asthma and COPD ExacerbationsBronchodilators, steroids, magnesium and parenteral β-agonists: Epinephrine or terbutaline: 0.3–0.5 mg or 0.25 mg SC every 20 min ×3: When inhaled drug cannot get in
- Vasopressors and InotropesLines, extravasation and titration: Extravasation: stop the infusion, aspirate, remove the catheter, mark and elevate. For catecholamines or phenylephrine, infiltrate phentolamine 5–10 mg in 10–15 mL saline subcutaneously as soon as possible (label: within 12 h). Alternatives: terbutaline or topical nitroglycerin.
- CEN: Genitourinary, Gynecologic and Early-Pregnancy EmergenciesExam pearls: Priapism over 4 h is a urology procedure, not oral terbutaline and a wait.
- Obstetric EmergenciesDrugs in pregnancy in the ICU: Betamethasone (12 mg IM, two doses 24 h apart) for likely delivery before 34 weeks raises glucose and WBC for days, mimicking infection. Magnesium before 32 weeks cut moderate or severe cerebral palsy from 3.5% to 1.9%, a secondary outcome (BEAM, Rouse 2008). Rho(D) immune globulin 300 mcg covers 30 mL of fetal whole blood. Terbutaline carries an FDA boxed warning ag
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Other pulmonary, obstetric and electrolyte infusions
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For education and exam preparation only. Follow your institution’s protocols. Study aid: check every dose against the order, the bag label, your pump library and your institution's protocol.