WASHINGTON — During 2001–2003, penicillins were the most commonly prescribed oral antibiotics in the United States, followed closely by macrolides, based on data from nine managed care plans.
But the pattern was highly dependent on infection sites, Katie J. Suda, Pharm.D., said in presenting a poster at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.
In addition, 5% of all oral antibiotic prescriptions were written for viral infections, including the common cold and influenza. Macrolides were most often prescribed for these infections, followed by penicillins, said Dr. Suda of the pharmacy administration office at Baptist Memorial Health Care Corp. in Memphis, Tenn.
The data collected from the managed care plans included 42,971 prescriptions for oral anti-infective drugs that were written for 23,762 patients. The average age of the patients who received these prescriptions was 34 years old, and two-thirds were women. The average duration of treatment was 10 days.
Penicillins were prescribed 29% of the time, followed by macrolides, 27%; fluoroquinolones, 15%; cephalosporins, 14%; tetracyclines, 8%; and other antibiotics, 7%.
Dr. Suda and her associates broke the infections into four main types: urinary tract, skin and soft tissue, upper respiratory tract, and lower respiratory tract.
Fluoroquinolones were the most commonly prescribed antibiotic class for urinary tract infections, used by about 31% of patients, followed by sulfonamides (24%). These rates showed little change over the 3 years of the study.
The most commonly prescribed class for skin and soft-tissue infections was first-generation cephalosporins, used by about 46% of patients. The next most common class was the fluoroquinolones (19%). Use of first-generation cephalosporins surged during the 3 years of the study, jumping from 39% of all antibiotic prescriptions for these infections in 2001 to 47% in 2002 and 51% in 2003, Dr. Suda said.
For patients with upper respiratory tract infections, the most commonly prescribed drug class was the macrolides, used by 33%, followed by the penicillins, used by about 27% of patients. The study period featured a rise in prescriptions of both macrolides, which increased from 28% in 2001 to 37% in 2003, and in fluoroquinolones, which rose from 7% of all prescriptions for this indication in 2001 to 13% in 2003. Penicillin use declined modestly, from 30% in 2001 to 27% in 2003.
Among patients with lower respiratory tract infections, the most commonly used class was the macrolides, in 43%, followed by the fluoroquinolones, in about 29%. During the study period, macrolide use was flat, but fluoroquinolone use jumped from 21% in 2001 to 32% in 2002 and 35% in 2003. During the same time, use of β-lactamase inhibitor agents dropped from 15% of prescriptions for this indication in 2001 to 2% in 2003.