BENZONATATE
Clinical safety rating: safe
Animal studies have demonstrated safety
Benzonatate is a local anesthetic structurally related to tetracaine. It suppresses cough by anesthetizing stretch receptors in the respiratory tract, reducing the cough reflex.
| Metabolism | Metabolized by plasma esterases (including pseudocholinesterase) to tetracaine and other metabolites. |
| Excretion | Primarily renal excretion of metabolites; unchanged benzonatate is negligible. Fecal elimination accounts for <5%. Biliary excretion is minimal. |
| Half-life | Terminal elimination half-life is approximately 3–8 hours in adults; prolonged in hepatic impairment. |
| Protein binding | Approximately 75–85% bound primarily to albumin. |
| Volume of Distribution | Approximately 3.5 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral: Estimated 20–30% due to extensive first-pass metabolism. |
| Onset of Action | Oral: 15–20 minutes. |
| Duration of Action | Oral: 3–8 hours; effect may wane with repeated use due to peripheral desensitization. |
100 mg to 200 mg orally three times daily as needed for cough.
| Dosage form | CAPSULE |
| Renal impairment | No specific dosage adjustment is recommended for renal impairment per manufacturer; however, caution and monitoring are advised. |
| Liver impairment | No specific dosage adjustment is recommended for hepatic impairment per manufacturer; however, caution is advised. |
| Pediatric use | Safety and efficacy have not been established in children under 10 years of age. For children ≥10 years, adult dosing can be considered. |
| Geriatric use | Elderly patients may be more sensitive to CNS effects; start at lower end of dosing range (100 mg three times daily) and monitor carefully. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
No significant drug interactions Do not chew or swallow capsules whole as it can cause local anesthesia of the oral mucosa and choking.
| Breastfeeding | No data on excretion in human milk; M/P ratio unknown. Benzonatate and its metabolites may be present in breast milk. Caution advised due to potential for infant CNS depression and apnea. Consider benefit of breastfeeding vs risk of drug exposure. |
| Teratogenic Risk | FDA Pregnancy Category C. First trimester: No adequate human studies; animal studies not available. Theoretical risk of fetal bradycardia and respiratory depression if used near term. Second and third trimesters: Avoid use due to potential for neonatal apnea and withdrawal; benzonatate is a local anesthetic with CNS depressant effects. |
■ FDA Black Box Warning
None
| Common Effects | Dizziness |
| Serious Effects |
["Hypersensitivity to benzonatate or related compounds (e.g., tetracaine, procaine)"]
| Precautions | ["Severe allergic reactions (e.g., bronchospasm, laryngospasm, cardiovascular collapse) have been reported, especially with chewing or sucking capsules.","Capsules must be swallowed whole to avoid oral mucosal anesthesia and choking hazard.","Use with caution in patients with hypersensitivity to ester-type local anesthetics.","Safety and efficacy in children <10 years not established."] |
| Food/Dietary | No significant food interactions. The manufacturer does not list any specific dietary restrictions, but alcohol may enhance central nervous system side effects such as drowsiness. |
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| Fetal Monitoring | Monitor maternal respiratory rate and oxygen saturation due to risk of CNS depression. Fetal heart rate monitoring if used near term. Newborns exposed in utero: observe for signs of respiratory depression, apnea, or withdrawal (e.g., irritability, poor feeding). |
| Fertility Effects | No human data on fertility effects. Animal reproduction studies not available. Theoretical risk based on local anesthetic properties; no specific impairment identified. |
| Clinical Pearls | Benzonatate is a peripherally acting antitussive that anesthetizes stretch receptors in the respiratory tract. Onset of action is within 15-20 minutes and lasts 3-8 hours. Capsules must be swallowed whole; chewing or sucking can cause oropharyngeal anesthesia and choking hazard. Use with caution in patients with a history of drug allergy to tetracaine or other ester-type anesthetics. It is contraindicated in children under 10 years due to increased risk of adverse effects. Overdose can cause seizures, cardiac arrest, and death; treatment is supportive with no specific antidote. |
| Patient Advice | Swallow the capsule whole; do not chew, suck, or crush it, as this can cause numbness in your mouth or throat and increase risk of choking. · Take the medication exactly as prescribed; do not take more than directed. · This medication may cause dizziness or drowsiness; avoid driving or operating machinery until you know how it affects you. · Contact your doctor if your cough persists for more than 5 days, or if it is accompanied by fever, rash, or persistent headache. · Keep out of reach of children; accidental ingestion can be fatal in children under 10. · Store at room temperature away from moisture and heat. |