COMBIVENT
Clinical safety rating: caution
Comprehensive clinical and safety monograph for COMBIVENT (COMBIVENT).
Combivent is a fixed-dose combination of ipratropium bromide, an anticholinergic agent that inhibits muscarinic receptors in bronchial smooth muscle leading to bronchodilation, and albuterol sulfate, a beta-2 adrenergic agonist that stimulates adenyl cyclase, increasing cyclic AMP, resulting in bronchodilation.
| Metabolism | Ipramatropium: partially metabolized by hydrolysis to inactive metabolites; Albuterol: primarily metabolized by sulfate conjugation via SULT1A3 and to a lesser extent by CYP450 enzymes (CYP3A4, CYP2D6) to 4'-O-sulfate. |
| Excretion | Ipratropium is primarily excreted renally as unchanged drug (approximately 50%) and metabolites (approximately 30%); fecal excretion accounts for about 10%. Albuterol undergoes hepatic metabolism to an inactive sulfate conjugate, with approximately 70-80% of a dose excreted renally as unchanged drug and metabolite; fecal excretion is minimal (<10%). |
| Half-life | Ipratropium: terminal elimination half-life of approximately 2 hours (range 1.5-4 hours) after inhalation. Albuterol: terminal elimination half-life of approximately 3.8-6 hours after inhalation; systemic half-life is clinically relevant for dosing frequency in asthma/COPD. |
| Protein binding | Ipratropium: approximately 0-9% bound to plasma proteins (predominantly albumin). Albuterol: approximately 10% bound to plasma proteins. |
| Volume of Distribution | Ipratropium: Vd approximately 2-4 L/kg (467 L for a 70 kg adult), indicating extensive tissue distribution. Albuterol: Vd approximately 1.5-2 L/kg (105-140 L for a 70 kg adult), consistent with moderate tissue distribution. |
| Bioavailability | Inhalation: Ipratropium absolute bioavailability of approximately 7-25% (due to pulmonary deposition and swallowed fraction). Albuterol inhaled bioavailability of approximately 10-20%. Oral bioavailability (swallowed) is low: ipratropium about 2-3%, albuterol about 30-50% but first-pass metabolism reduces systemic exposure. |
| Onset of Action | Inhalation: Ipratropium onset within 15 minutes, peak effect at 1-2 hours. Albuterol onset within 5-15 minutes, peak effect at 30-60 minutes. Combined product provides rapid bronchodilation. |
| Duration of Action | Inhalation: Ipratropium duration of 4-6 hours; albuterol duration of 4-6 hours. Clinically, Combivent provides bronchodilation for up to 5 hours in COPD patients. |
| Molecular Weight | Ipratropium: 412.4 Da; Albuterol: 239.3 Da (average 325.85 Da) |
2 inhalations (ipratropium 18 mcg and albuterol 103 mcg per actuation) via oral inhalation 4 times daily; maximum 12 inhalations in 24 hours.
| Dosage form | AEROSOL, METERED |
| Renal impairment | No dose adjustment required for mild-to-moderate renal impairment (CrCl >30 mL/min). Caution in severe impairment (CrCl <30 mL/min) or dialysis; use reduced frequency or alternative therapy due to potential for systemic accumulation. |
| Liver impairment | No specific Child-Pugh based guidelines; caution in severe hepatic impairment (Child-Pugh class C) due to reduced clearance of albuterol, consider dose reduction or extended interval. |
| Pediatric use | Not recommended for children <6 years. For ≥6 years: 2 inhalations 4 times daily as needed, up to 12 inhalations/day. |
| Geriatric use | No specific dose adjustment; monitor for anticholinergic effects (e.g., dry mouth, urinary retention) and beta-adrenergic effects (e.g., tachycardia, tremor). Ensure proper inhaler technique; consider spacer use. |
| 1st trimester | No adequate studies in pregnant women; use only if clearly needed. Avoid due to potential anticholinergic effects. |
| 2nd trimester | No adequate studies; potential risk of fetal tachycardia or GI effects; weigh benefits vs risks. |
| 3rd trimester | May cause uterine relaxation and delay labor; use with caution near term. |
Clinical note
Comprehensive clinical and safety monograph for COMBIVENT (COMBIVENT).
| Placental transfer | Albuterol crosses placenta; ipratropium has limited data but likely minimal transfer due to quaternary ammonium structure. |
| Breastfeeding | Ipratropium is poorly absorbed orally and likely not excreted in significant amounts in breast milk; albuterol is excreted in small amounts. Consider risk to benefit, especially in preterm infants. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to ipratropium, albuterol, or any componentHistory of hypersensitivity to atropine or its derivatives
| Precautions | Paradoxical bronchospasm, Immediate hypersensitivity reactions, Deterioration in renal function (ipratropium eliminated renally), Cardiovascular effects: tachycardia, arrhythmias, hypertension (albuterol), Hypokalemia (albuterol), Increased intraocular pressure with nebulized ipratropium in glaucoma patients, Urinary retention in patients with prostatic hyperplasia or bladder neck obstruction |
| Food/Dietary | No specific food interactions are clinically significant. Avoid excessive caffeine intake (coffee, tea, cola, chocolate) as it may increase the risk of stimulant side effects (tremor, palpitations). Maintain adequate hydration to help manage possible dry mouth from ipratropium. |
Loading safety data…
| Lactation Rating |
| L3 - Moderately Safe |
| Teratogenic Risk | Pregnancy Category C. No adequate well-controlled studies in pregnant women. In animal studies, albuterol sulfate showed teratogenicity (cleft palate) at high doses; ipratropium bromide showed no teratogenic effects. Risk cannot be ruled out; use only if potential benefit justifies potential risk to fetus. First trimester: potential risk based on animal data. Second/third trimesters: albuterol may inhibit uterine contractions and cause maternal tachycardia, which may affect fetal heart rate; avoid near term due to possible neonatal hypoglycemia and hypokalemia. |
| Fetal Monitoring | Monitor maternal heart rate, blood pressure, serum potassium, and signs of bronchospasm. Fetal monitoring: assess fetal heart rate and uterine activity; ultrasound for fetal growth if used long-term. Watch for maternal tachyarrhythmias, especially if used concomitantly with other sympathomimetics. |
| Fertility Effects | No specific data on Combivent effects on human fertility. Animal studies: albuterol at high doses impaired fertility in rats; ipratropium showed no adverse effects. Clinical relevance unknown. |
| Clinical Pearls | Combivent is a fixed-dose combination of ipratropium bromide (anticholinergic) and albuterol sulfate (beta-2 agonist) for COPD exacerbations. It should be used with caution in patients with narrow-angle glaucoma, bladder neck obstruction, or prostatic hypertrophy. Shake well before use. Rinse mouth after inhalation to prevent oral candidiasis and dysphonia. Monitor for paradoxical bronchospasm, hypokalemia, and cardiovascular effects (tachycardia, hypertension). Not indicated for acute episodes of asthma or as rescue monotherapy; consider separate short-acting beta-agonist for acute symptoms. |
| Patient Advice | Use exactly as prescribed; do not increase dose or frequency without consulting your doctor. · Shake the inhaler well before each use (at least 10-15 seconds). · Prime the inhaler by spraying 4 test sprays into the air (away from face) before first use or if not used for more than 3 days. · Rinse your mouth with water after each use to reduce the risk of thrush (oral fungal infection) and hoarseness. · Seek immediate medical attention if you experience sudden worsening of breathing, chest pain, or signs of allergic reaction (rash, hives, swelling). · Inform your doctor if you have glaucoma, difficulty urinating, enlarged prostate, heart problems, or seizures. · Do not use with other inhaled medicines unless instructed by your doctor. · Keep inhaler clean; wipe mouthpiece with a dry cloth weekly. |