Introduction
Benzonatate is a non-narcotic antitussive medication approved by the FDA in 1958. It is chemically related to local anesthetics such as tetracaine and is classified as a peripherally-acting cough suppressant. Unlike centrally-acting opioid antitussives, benzonatate works through local anesthetic effects on the respiratory tract.
Mechanism of Action
Benzonatate exerts its antitussive effect through anesthesia of the stretch receptors located in the respiratory passages, lungs, and pleura. By numbing these receptors, it reduces the cough reflex at its peripheral source. The drug may also have a central effect on the cough center in the medulla, though this is considered secondary to its peripheral action.
Indications
Benzonatate is indicated for the symptomatic relief of cough. It is particularly useful for:
- Acute cough associated with respiratory tract infections
- Chronic cough in various respiratory conditions
- Post-operative cough
Dosage and Administration
Adults and children over 10 years: 100 mg three times daily as needed, up to 600 mg daily Administration: Swallow capsules whole; do not crush, chew, or dissolve in mouth Special populations:- Renal impairment: Use with caution; no specific dosage adjustment recommendations
- Hepatic impairment: Use with caution; limited data available
- Elderly: Consider starting at lower end of dosing range
- Pediatrics: Safety and effectiveness under age 10 not established
Pharmacokinetics
Absorption: Rapidly absorbed from GI tract Distribution: Distributed throughout the body Metabolism: Hydrolyzed by esterases to metabolites including para-aminobenzoic acid (PABA) Elimination: Primarily renal excretion; half-life unknown Onset of action: 15-20 minutes Duration of effect: 3-8 hoursContraindications
- Hypersensitivity to benzonatate or related compounds
- History of allergic reactions to PABA or procaine
- Children under 10 years of age
Warnings and Precautions
Black Box Warning: Risk of severe hypersensitivity reactions including bronchospasm, laryngospasm, and cardiovascular collapse, particularly if capsules are chewed or dissolved in mouth Other precautions:- CNS effects: May cause sedation; caution when operating machinery
- Psychiatric effects: Rare reports of confusion and visual hallucinations
- Pregnancy: Category C - use only if potential benefit justifies potential risk
- Lactation: Not recommended; excreted in breast milk
Drug Interactions
- CNS depressants: Additive sedation with alcohol, benzodiazepines, opioids
- Local anesthetics: Potential for additive effects
- Cholinesterase inhibitors: Theoretical interaction due to ester hydrolysis
Adverse Effects
Common (≥1%):- Sedation
- Dizziness
- Headache
- Constipation
- Nausea
- Nasal congestion
- Hypersensitivity reactions
- Bronchospasm
- Laryngospasm
- Cardiovascular collapse
- CNS depression
- Visual hallucinations
Monitoring Parameters
- Cough frequency and severity
- Respiratory status
- CNS effects (sedation, dizziness)
- Signs of hypersensitivity reactions
- Overall therapeutic response
Patient Education
- Swallow capsules whole; do not chew or break
- Report any signs of allergic reaction immediately (rash, difficulty breathing, swelling)
- Avoid alcohol and other CNS depressants during therapy
- Be cautious when driving or operating machinery
- Store at room temperature away from children (risk of accidental ingestion)
- Do not exceed recommended dosage
- Contact healthcare provider if cough persists beyond 7 days or is accompanied by fever, rash, or persistent headache
References
1. FDA Prescribing Information: Tessalon (benzonatate) capsules 2. American College of Chest Physicians Cough Guidelines (2018) 3. Lexicomp Drug Information: Benzonatate 4. Micromedex Solutions: Benzonatate monograph 5. Clinical Pharmacology [database online]: Benzonatate 6. Chest Journal: "Diagnosis and Management of Cough Executive Summary" (2006) 7. Drug Facts and Comparisons (2023 edition)
Note: This monograph provides general information for healthcare professionals. Always consult current prescribing information and clinical guidelines for specific patient care decisions.