PRIMATENE MIST
Clinical safety rating
cautionComprehensive clinical and safety monograph for PRIMATENE MIST (PRIMATENE MIST).
Epinephrine is a sympathomimetic amine that acts as a non-selective agonist at alpha-1, alpha-2, beta-1, and beta-2 adrenergic receptors. Activation of beta-2 receptors in bronchial smooth muscle causes relaxation and bronchodilation, relieving bronchospasm. Alpha-adrenergic activation can cause vasoconstriction and reduce mucosal edema.
| Metabolism | Epinephrine is metabolized primarily by monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT) in the liver and other tissues, forming inactive metabolites like metanephrine and vanillylmandelic acid (VMA). |
| Excretion | Renal excretion: approximately 60-70% as unchanged drug and metabolites. Biliary/fecal: minor, less than 10%. |
| Half-life | Terminal elimination half-life: 3-4 hours. Clinical context: Requires repeated dosing for sustained bronchodilation; shorter half-life necessitates q4-6h dosing. |
| Protein binding | 15-20% bound to albumin. |
| Volume of Distribution | Vd: 2-3 L/kg. Indicates extensive tissue distribution, not confined to plasma. |
| Bioavailability | Inhalation: 10-20% (due to pulmonary deposition and first-pass metabolism). |
| Onset of Action | Inhalation: 5-15 minutes. |
| Duration of Action | 2-4 hours. Clinical notes: Tolerance may develop with frequent use, reducing duration. |
| Molecular Weight | 183.2 |
1-2 inhalations (0.5-1 mg epinephrine base) as a single dose; may repeat every 3-4 hours as needed, not to exceed 12 inhalations in 24 hours.
| Dosage form | AEROSOL, METERED |
| Renal impairment | No specific GFR-based dose modifications established; use with caution in severe renal impairment due to potential accumulation of metabolites. |
| Liver impairment | No specific Child-Pugh based dose modifications; caution in severe hepatic impairment due to reduced clearance. |
| Pediatric use | Children <4 years: not recommended. Children 4-12 years: 1 inhalation (0.5 mg epinephrine base) every 3-4 hours as needed, not to exceed 8 inhalations in 24 hours. Children >12 years: same as adult dosing. |
| Geriatric use | Initiate with lowest effective dose (1 inhalation) due to increased sensitivity and higher risk of adverse cardiac effects; monitor closely. |
| 1st trimester | Avoid use; epinephrine is teratogenic in animal studies and may cause fetal hypoxia due to vasoconstriction. |
| 2nd trimester | Avoid use; risk of maternal hypertension and uterine vasoconstriction leading to fetal hypoxia. |
| 3rd trimester | Avoid use; may precipitate preterm labor or fetal distress; also used as an abortifacient. |
Clinical note
Comprehensive clinical and safety monograph for PRIMATENE MIST (PRIMATENE MIST).
| Placental transfer | Epinephrine crosses the placenta; it may cause fetal tachycardia, hypertension, and decreased uterine blood flow. |
| Breastfeeding | Epinephrine is excreted into breast milk in minimal amounts and has poor oral bioavailability, so it is unlikely to affect the infant. However, use caution due to potential maternal cardiovascular effects and possible impact on milk supply. |
| Lactation Rating | L2 (Safer) |
| Teratogenic Risk | Primatene Mist contains epinephrine, a sympathomimetic amine. In pregnant women, epinephrine may cause fetal hypoxia due to uterine vasoconstriction. First trimester: limited data, but animal studies show teratogenic effects at high doses; avoid if possible. Second and third trimesters: use only if clearly needed; may reduce uterine blood flow and induce premature labor. Category C: risk cannot be ruled out. |
| Fetal Monitoring | Monitor maternal heart rate, blood pressure, and signs of cardiac arrhythmias. Assess fetal heart rate patterns for signs of distress. Monitor uterine activity for evidence of premature labor or hyperstimulation. Evaluate maternal respiratory status and bronchodilator response. |
| Fertility Effects | No specific studies on fertility effects in humans. In animal studies, epinephrine at high doses caused impaired fertility and increased preimplantation loss. Relevance to humans is unknown. May affect uterine contractility and implantation if used around conception. |
■ FDA Black Box Warning
None for PRIMATENE MIST specifically. However, epinephrine-containing products carry a warning for risk of serious adverse events due to inappropriate use.
| Serious Effects |
Hypersensitivity to epinephrine or any componentCardiac arrhythmiasHypertensionHyperthyroidismDiabetesNarrow-angle glaucomaConcurrent use with nonselective beta-blockersLocal anesthesia in fingers, toes, or other areas with end arteries
| Precautions | May cause paradoxical bronchospasm: discontinue immediately if wheezing worsens, Overuse may lead to tolerance and increased risk of severe asthma attacks, Avoid in patients with significant cardiovascular disease, hypertension, hyperthyroidism, or diabetes unless directed by a physician, May cause palpitations, tachycardia, arrhythmias, and increased blood pressure |
| Food/Dietary | No specific food interactions. Avoid caffeine-containing beverages (coffee, tea, colas) as they may increase the risk of cardiovascular side effects. |
| Clinical Pearls | Primatene Mist contains epinephrine, a non-selective beta-agonist and alpha-agonist. It is indicated for temporary relief of mild intermittent asthma symptoms. Use is contraindicated in patients with coronary artery disease, hypertension, hyperthyroidism, or diabetes due to risk of tachycardia, hypertension, and hyperglycemia. Overuse can lead to tolerance and severe bronchospasm. Do not exceed 2 inhalations per episode or more than 8 inhalations per day. If symptoms persist or worsen, seek immediate medical attention. Primatene Mist is a CFC-free HFA formulation. |
| Patient Advice | This medication is for temporary relief only; it should not be used as a mainstay of asthma therapy. · Do not use more than 2 puffs per attack or more than 8 puffs in 24 hours. · If you need more than 2 puffs per attack or more than 8 puffs per day, contact your doctor. · Seek emergency medical help if you have worsening asthma symptoms or if the medication does not provide relief. · Shake the inhaler well before each use. · Do not share your inhaler with others. · Store at room temperature away from heat and open flame. · Common side effects include nervousness, rapid heartbeat, and jitteriness. · Avoid use if you have heart disease, high blood pressure, diabetes, or thyroid disease without consulting a doctor. · Do not use within 4 hours of bedtime to avoid insomnia. |
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