benzonatate
Brand: Tessalon, Tessalon Perles, Zonatuss
Drug Class: antitussive
Drug Family: local anesthetic antitussive
Subclass: non-opioid peripherally acting antitussive
Organ Systems: respiratory
Mechanism of Action
Anesthetizes stretch receptors in the lungs, pleura, and respiratory passages, reducing the cough reflex without suppressing the respiratory center in the CNS. Structurally related to tetracaine (a local anesthetic).
stretch receptors in lungs and pleurasodium channels (local anesthetic action)
Indications
- symptomatic relief of non-productive cough
Contraindications
- hypersensitivity to benzonatate or related compounds (para-aminobenzoic acid derivatives, procaine, tetracaine)
- children under 10 years of age
Adverse Effects
Common
- sedation
- headache
- dizziness
- nausea
- constipation
- nasal congestion
- pruritus
Serious
- severe hypersensitivity reactions (bronchospasm, laryngospasm, cardiovascular collapse) from oral mucosa absorption if capsule is chewed or sucked
- CNS toxicity (seizures, cardiac arrhythmias, cardiac arrest) if capsule is chewed or crushed — potentially fatal
- accidental overdose in children — pediatric fatalities reported
Pharmacokinetics (ADME)
| Absorption | oral; onset within 15-20 minutes |
| Distribution | not extensively characterized |
| Metabolism | hepatic; ester hydrolysis releases para-aminobenzoic acid (PABA) derivative |
| Excretion | renal |
| Half-life | approximately 3-8 hours |
| Onset | 15-20 minutes |
| Peak | 30-90 minutes |
| Duration | 3-8 hours |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| CNS depressants (opioids, benzodiazepines, alcohol, antihistamines) | additive CNS depression; increased sedation | moderate |
| MAO inhibitors | potential for enhanced CNS effects; use with caution | moderate |
Nursing Considerations
- CRITICAL: Instruct patients to swallow capsules whole — never chew, suck, crush, or dissolve them. If the capsule is broken in the mouth, the local anesthetic effect causes rapid oral/pharyngeal anesthesia and absorption can cause severe CNS and cardiovascular toxicity, including seizures and cardiac arrest.
- Keep out of reach of children; pediatric fatalities from accidental ingestion have been reported. Benzonatate is contraindicated in children under 10 years.
- Assess effectiveness: note whether the cough is productive or non-productive. Benzonatate is indicated for non-productive cough; suppressing a productive cough can impair secretion clearance and worsen respiratory conditions.
- Assess respiratory status before and after administration. Benzonatate should not be used in conditions where suppression of the cough reflex is hazardous (e.g., post-operative patients at risk for aspiration, patients with copious secretions).
- Monitor for hypersensitivity reactions, especially after the first dose. Patients with known hypersensitivity to PABA derivatives (procaine, tetracaine) are at elevated risk.
- Advise patients that sedation and dizziness may occur; caution regarding driving and operating machinery.
- Do not combine benzonatate with other antitussives without clinical justification; combined cough suppression can result in dangerous retention of secretions.
- Benzonatate is not controlled but has potential for misuse; it has been identified in overdose toxicology reports. Assess medication history if overdose is suspected.
Clinical Pearls
- Benzonatate is unique among antitussives: it acts peripherally on pulmonary stretch receptors rather than centrally on the cough center — making it useful when central suppression (e.g., with opioids) is undesirable.
- The FDA has issued multiple safety communications regarding benzonatate overdose deaths in children under 10; the drug was not intended for pediatric use and must be stored out of reach.
- Benzonatate has no opioid activity and is not a controlled substance — this makes it a common alternative when opioid antitussives (codeine) are contraindicated.
- Clinical evidence for efficacy of benzonatate over placebo in acute cough is limited; systematic reviews find modest benefit at best. It is nevertheless widely prescribed due to favorable safety profile (when swallowed intact) and non-opioid mechanism.
Safety Profile
Pregnancy use-with-caution
Lactation unknown
Renal Adjustment Not required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.