What is BGT Syrup (Benzonatate)?
Benzonatate is not available as a syrup formulation—it is FDA-approved only as an oral capsule for symptomatic relief of cough. 1
Approved Formulation and Indication
- Benzonatate is indicated solely for symptomatic cough relief and is available only in capsule form (typically 100 mg or 200 mg capsules). 1
- The medication works as a peripherally-acting non-opioid antitussive by anesthetizing stretch receptors in the lungs and vagal sensory nerve fibers, thereby reducing the cough reflex. 2, 3
- It inhibits voltage-gated sodium channels (particularly Nav1.7) in vagal sensory neurons, similar to local anesthetics. 4
Clinical Positioning in Cough Management
Benzonatate occupies a fourth-line position in the treatment algorithm for refractory cough according to the American College of Chest Physicians guidelines. 2, 3
The stepwise approach is:
- First-line: Demulcents (simple linctus, butamirate, glycerol-based syrups). 2, 5
- Second-line: Opioid derivatives (pholcodine, hydrocodone, dihydrocodeine, or morphine) titrated to acceptable side effects. 2, 5
- Third-line: Peripherally-acting antitussives (levodropropizine, moguisteine, levocloperastine, or sodium cromoglycate). 2, 3
- Fourth-line: Local anesthetics including benzonatate at 100-200 mg three to four times daily or nebulized lidocaine. 2, 3
Dosing
- The recommended dose is 100-200 mg three to four times daily (not to exceed 600 mg/day). 3
- Benzonatate has shown effectiveness in controlling cough in 80% of patients with malignant pulmonary involvement, particularly when opioids were ineffective. 2, 3
Critical Safety Concerns
Benzonatate carries significant overdose risk with rapid onset of life-threatening toxicity, even with small numbers of capsules. 6, 7
- Onset of toxicity can occur in less than 5 minutes after ingestion. 7
- Most common severe manifestations include cardiac arrest (29/36 cases), seizures (24/36 cases), and dysrhythmias (24/36 cases) in overdose series. 7
- Even with return of spontaneous circulation (achieved in 23/28 cardiac arrest cases), most patients had significant neurologic deficits or end organ damage, with only 5 surviving with good neurologic outcome. 7
- Capsules must be swallowed whole and never chewed or dissolved, as this releases the medication rapidly and can cause severe local anesthetic effects in the oropharynx. 6
Special Populations and Precautions
- Aspiration risk: The American Geriatrics Society recommends assessing aspiration risk before using benzonatate in frail patients or those with cancer, as local anesthetics increase aspiration risk. 2, 5
- Porphyria: Benzonatate is safe in patients with porphyria, with no evidence suggesting it triggers acute porphyria attacks. 3
Pharmacokinetics
- Benzonatate undergoes rapid ester hydrolysis in plasma, producing 4-(butylamino)benzoic acid (BBA) and methylated polyethylene glycol polymer. 8, 9
- After a 100 mg dose, benzonatate reaches maximum concentration (Cmax) of 1063 ± 460 ng/mL with a half-life of 1.01 ± 0.41 hours. 9
- The metabolite BBA has a half-life of 1.32 ± 0.29 hours. 9
Duration of Use
- For acute cough due to upper respiratory infections, limit treatment to the duration of symptoms, typically 7-10 days. 3
- For chronic bronchitis, benzonatate is recommended only for short-term symptomatic relief. 3
- Discontinue if symptoms persist beyond 1 week, as prolonged cough may indicate a more serious underlying condition requiring diagnostic evaluation. 3
Common Pitfall to Avoid
Do not use benzonatate as first-line therapy for cough—it should only be tried after failure of demulcents, opioids, and other peripheral antitussives. 2, 3 The evidence supporting its use comes primarily from case studies and observational data rather than large randomized controlled trials. 2