Can an elderly patient on anastrozole (Aromatase Inhibitor) take benzonatate (Cough Suppressant)?

Can an Elderly Patient on Anastrozole Take Benzonatate?

Yes, an elderly patient on anastrozole can take benzonatate for cough suppression, as there are no known drug-drug interactions between these medications and benzonatate has documented efficacy in cancer-related cough, though careful attention to proper dosing and storage is critical to prevent life-threatening overdose.

Evidence Supporting Benzonatate Use in Cancer Patients

• Benzonatate effectively controlled cough in 80% of 21 patients with malignant pulmonary involvement in case series data 1
• Benzonatate was effective for cough associated with lung cancer that was unresponsive to opioid treatment in three patients 1
• As a peripherally acting antitussive, benzonatate achieved symptomatic relief in patients with opioid-resistant cough in advanced cancer 2

No Drug Interaction Concerns

• There are no documented pharmacokinetic or pharmacodynamic interactions between anastrozole (an aromatase inhibitor) and benzonatate (a peripherally acting cough suppressant) 1
• Anastrozole's primary side effects include joint stiffness, arthralgias, vasomotor symptoms, hypertension, dry eyes, and vaginal dryness—none of which are exacerbated by benzonatate 1
• The bone health concerns with anastrozole (requiring baseline bone density assessment, calcium/vitamin D supplementation, and consideration of bisphosphonates) are unrelated to benzonatate use 1

Critical Safety Warnings for Benzonatate in Elderly Patients

The primary concern is benzonatate's narrow therapeutic window and potential for rapid, life-threatening toxicity with overdose:

• Signs and symptoms of benzonatate overdose include seizures, cardiac arrest, coma, apnea, tachycardia, and respiratory arrest—occurring within 15 minutes of ingestion in some patients 3
• Fatal outcomes occurred in 20 of 31 overdose cases reported to the FDA Adverse Event Reporting System, with dysrhythmias (ventricular dysrhythmia, cardiac arrest, asystole) being the primary cause of death rather than seizures 3, 4
• A median dose of 200 mg or greater (as little as one capsule beyond prescribed dose) can produce serious outcomes 4
• Cardiac arrest has been documented in adults following benzonatate overdose with alcohol co-ingestion 5

Specific Prescribing Recommendations for Elderly Patients

Prescribe the lowest effective dose with explicit overdose counseling:

• Standard dosing is 100-200 mg three times daily, but elderly patients may benefit from starting at 100 mg to assess tolerance 1
• Counsel patients explicitly: Benzonatate capsules must be swallowed whole and never chewed, crushed, or dissolved, as local anesthetic effects in the mouth can occur 3
• Emphasize safe storage away from other medications to prevent accidental overdose 3
• Warn about signs of overdose requiring immediate emergency care: confusion, seizures, chest pain, irregular heartbeat, or difficulty breathing 3, 4

Alternative Cough Suppressants to Consider

If concerns about benzonatate safety outweigh benefits in a particular elderly patient:

• Centrally acting cough suppressants such as dihydrocodeine and hydrocodone are recommended for patients with cough and lung cancer, though they carry their own risks in elderly patients 1
• These opioid options may be preferable if the patient has cognitive impairment or medication management concerns that increase overdose risk 1

Common Pitfalls to Avoid

• Do not assume benzonatate is "safer" than opioids simply because it is non-narcotic—it has a narrow therapeutic index and rapid onset of toxicity 3, 4
• Do not prescribe large quantities (limit to 7-14 day supply initially) to minimize overdose risk 3
• Do not neglect to assess the patient's ability to safely manage medications, particularly in elderly patients with cognitive impairment or those living alone 3