Is amoxicillin or Augmentin (amoxicillin/clavulanic acid) more effective for treating upper respiratory infections in smokers?

From the Guidelines

Augmentin (amoxicillin/clavulanic acid) is the preferred treatment for upper respiratory infections in smokers due to its ability to combat beta-lactamase-producing bacteria. According to the clinical practice guideline update for adult sinusitis 1, smokers are at a higher risk of being infected with amoxicillin-resistant organisms, making Augmentin a more effective choice. The guideline recommends considering Augmentin instead of amoxicillin alone for initial management of acute bacterial rhinosinusitis (ABRS) in adults with factors such as smoking, recent antibiotic use, or close contact with someone who has been treated with antibiotics.

The use of high-dose amoxicillin with clavulanate (2 g orally twice daily or 90 mg/kg/d orally twice daily) is recommended for adults with ABRS who are at a high risk of being infected with an amoxicillin-resistant organism 1. This is because the clavulanic acid in Augmentin inhibits beta-lactamase enzymes, allowing the amoxicillin component to work more effectively against the infection.

Key points to consider when prescribing Augmentin for upper respiratory infections in smokers include:

• The recommended dosage is 875/125 mg taken twice daily for 7-10 days
• Side effects may include diarrhea, nausea, and rash, which are more common with Augmentin than with amoxicillin alone
• Taking Augmentin with food can help reduce gastrointestinal side effects
• It's essential to complete the full course of antibiotics even if symptoms improve before finishing the prescription
• Smokers should be advised that quitting smoking can improve treatment outcomes and reduce the risk of future respiratory infections, as smoking damages the respiratory tract's natural defense mechanisms and alters the bacterial flora in the airways.

Additionally, the IDSA clinical practice guideline for acute bacterial rhinosinusitis in children and adults also recommends using amoxicillin-clavulanate instead of amoxicillin alone for empiric antimicrobial therapy of ABRS in adults 1. However, the most recent and highest quality study 1 provides more specific guidance on the use of Augmentin in smokers.

From the Research

Comparison of Amoxicillin and Augmentin for Upper Respiratory Infections in Smokers

• Amoxicillin and Augmentin (amoxicillin/clavulanic acid) are both effective antibiotics used to treat upper respiratory infections, but their efficacy in smokers may vary due to differences in pharmacokinetics and the presence of beta-lactamase-producing pathogens 2, 3.
• A study published in 2004 found that Augmentin has a broad-spectrum of antibacterial activity, coverage of beta-lactamase-producing pathogens, and a favorable pharmacokinetic/pharmacodynamic profile, making it an effective treatment for community-acquired respiratory tract infections 2.
• Another study published in 1987 found that cigarette smoking has deleterious effects on the respiratory tract and increases the risk of chronic bronchitis, which is often caused by bacterial pathogens such as Haemophilus influenzae, Streptococcus pneumoniae, and Branhamella catarrhalis 3.
• The same study found that amoxicillin/clavulanic acid is an effective treatment for exacerbations of chronic bronchitis, especially in cases where the pathogens are resistant to other antibiotics 3.
• A pilot study published in 1982 found that Augmentin is effective in treating lower respiratory tract infections, with a good clinical response in 10 out of 13 patients, and peak levels of amoxycillin and clavulanic acid in the blood and sputum were achieved at a later time in patients compared to healthy volunteers 4.
• A comparison study published in 1987 found that cefuroxime axetil and Augmentin have similar efficacy and safety profiles in the treatment of upper respiratory tract infections, with a success rate of 97% and 98%, respectively 5.
• A more recent study published in 2022 found that both amoxicillin and Augmentin are effective for antimicrobial postexposure prophylaxis following Bacillus anthracis inhalational exposure in cynomolgus macaques, with complete protection observed in all treated animals 6.

Efficacy in Smokers

• While there is limited direct evidence comparing the efficacy of amoxicillin and Augmentin specifically in smokers, the available studies suggest that Augmentin may be a more effective treatment option due to its broad-spectrum activity and coverage of beta-lactamase-producing pathogens 2, 3.
• However, the choice of antibiotic should be based on individual patient factors, such as the severity of the infection, presence of comorbidities, and potential allergies or interactions with other medications.

Pharmacokinetics and Resistance

• The pharmacokinetics of amoxicillin and Augmentin may be affected by smoking, with peak levels achieved at a later time in smokers compared to non-smokers 4.
• The emergence of antibiotic-resistant pathogens, such as beta-lactamase-producing H. influenzae and S. pneumoniae, is a concern in the treatment of upper respiratory infections, and Augmentin may be a more effective option in cases where resistance is suspected 2, 3.