Pharmacology Rounds: Cough, Cough: Do Anti-Tussives Work?

Pharmacology Rounds: Cough, Cough: Do Antitussives Work?

Gita Pensa, MD, and Bryan Hayes, PharmD, DABAT

Bryan Hayes and Gita Pensa discuss antitussive agents and the symptomatic relief of cough.

Nonpharmacologic interventions are frequently recommended, but evidence is scarce: These are generally low risk and often recommended

• Oral fluids
• Lozenges and hard candy
  • Avoid in very young children due to choking risk
• Honey
  • Limited evidence does support its use
  • Avoid in infants under 1 year due to risk of infantile botulism

Children

• No cough medications are recommended for children under 12 years
  • Significant side effects and no demonstrated clinical benefit
• Honey is recommended for children over 1 year 
• Hard candy is endorsed by the American Academy of Pediatrics
• Caution parents regarding naturopathic or home remedies with unknown ingredients

Dextromethorphan

• Decreases sensitivity of cough receptors (cough suppressant)
• The limited evidence for its use may be outweighed by its side effects
• Structurally related to codeine
• Frequently abused for euphoria
• Behavioral disturbances, respiratory depression possible at higher doses
• May cross-react with phencyclidine (PCP) in urine drug screens
• “DM” on over-the-counter (OTC) preparations indicates dextromethorphan

Guaifenesin

• Expectorant
• Thins out secretions to enable coughing them out
• No good evidence to show it is better than fluids alone
• Causes some gastrointestinal irritation
• Present in many multi-agent OTC preparations

Albuterol metered dose inhaler (MDI)

• Often recommended in bronchitis
• Indicated in asthmatic patients with cough
  • No clear evidence to support its use in non-asthmatic patients
• Patients must be cautioned not to exceed recommended dosing to avoid side effects
• May increase cough in first minutes after use

Benzonatate (Tessalon)

• Topical anesthetic for respiratory stretch receptors
• Little data to support use
• Cases of cardiac arrest and significant toxicity in children under 10 years when not used properly
• Advise patients not to bite
  • Can cause loss of airway-protective sensation

Nebulized lidocaine

• Not first line
• Some evidence to support benefit for selected patients with severe cough
• Must administer in monitored setting
  • Not for home use

Combination agent precautions

• OTC cough and cold remedies often have numerous agents
  • Decongestants are often added in, which pose risk and side effects
  • Warn patients to read labels for ingredients
  • Caution to avoid accidental overdose when using more than one OTC preparation
• Pseudoephedrine may cause jitteriness, anxiety, overstimulation, tachycardia, and elevated BP
  • Carries a significant risk to patients with hypertension and cardiac conditions
  • Advise patients to avoid before bed due to stimulant properties
    • Alternative nighttime preparations with antihistamines may be used if indicated
  • Pseudoephedrine is used in illicit manufacturing of methamphetamines
  • Phenylephrine is now substituted in many products
    • Generally less effective at recommended dosing
• Brand name “Coricidin HBP” is marketed to patients with hypertension
  • Generally same antitussives without decongestants added
  • Chlorpheniramine also used (antihistamine)

Codeine

• Long history of use as cough suppressant
  • Directly affects cough at medulla level
• May work better than most other agents, but not recommended due to significant risks
• Metabolized at very different rates in different patients
  • Dosing and respiratory depression is unpredictable
• Opioid warnings
• Avoid use in children
  • Somnolence, respiratory depression, and death

Subacute and chronic cough

• Considering underlying cause is beneficial
  • Consider serious causes such as lung cancer in a smoker
• Targeted treatment of possible underlying cause is preferable to continued antitussive use when possible
• Consider causes such as allergies, gastroesophageal reflux disease (GERD), occupational irritants, cough-variant asthma
• Angiotensin-converting enzyme (ACE) inhibitor–induced cough
  • Can start at any point during treatment
  • Can switch to an angiotensin receptor blocker (ARB), which does not cause cough
• Consider pertussis in severe cough lasting over 2 weeks
  • Post-tussive emesis a hallmark
  • Macrolide antibiotic indicated
    • Will help decrease spread but may not work quickly to diminish cough
• Other drugs such as gabapentin used for true chronic cough
  • Not generally started from urgent/acute care settings