Drug Update: Chlamydia trachomatis

OB/GYN News, Dec 15, 1999 by Mitchel L. Zoler, Miriam E. Tucker

All sexually active women aged 15-24 should be screened for genital infection with Chlamydia trachomatis at least yearly Prevalence in this group ranges from 1%-2% in some parts of the country to 15%-18% in others. Some experts advise screening every 6 months in high prevalence areas.

Older women who are sexually active with multiple partners and adolescent and young adult males should also be screened periodically This has been made easier in the last year with the availability of urine screens.

Treatment is fairly straightforward. There are two equally effective, first-line drugs for nonpregnant patients: Azithromycin is given as a single dose; doxycycline is much cheaper. Other treatment options are generally considered second-line alternatives.

The recommended drugs and dosages are the same for postpubescent patients of all ages.

For pregnant patients, doxycycline and ofloxacin are contraindicated. Azithromycin is widely used to treat pregnant women even though it is not approved for use during pregnancy.

DRUG              DOSAGE        COST/TREATMENT [*]
azithromycin      1 g orally,   $20.35 (powder)
 (Zithromax)      single dose
doxycycline       100 mg orally $7.56
                  b.i.d. for 7
                  days
erythromycin base 500 mg orally $6.72
                  q.i.d. for 7
                  days
erythromycin      800 mg orally $15.12
 ethylsuccinate   q.i.d. for 7
                  days
ofloxacin         300 mg orally $62.44
 (Floxin)         b.i.d. for 7
                  days
amoxicillin       500 mg orally $7.56
                  t.i.d. for 7
                  days
DRUG              COMMENT [**]
azithromycin      Considered first-line because of its
 (Zithromax)      ease of use and assured compliance
                  if ingestion is directly observed.
                  Gastrointestinal side effects occur
                  occasionally but are generally well
                  tolerated. Not approved for use in
                  pregnancy, but many physicians
                  prescribe it to pregnant women anyway
                  because there are no specific
                  contraindications and few good
                  alternatives exist. Cost is the major
                  downside.
doxycycline       As effective as azithromycin, but many
                  more doses needed, making compliance
                  much harder to ensure. Low cost is the
                  major advantage. Some data suggest that
                  fewer than 7 days might be enough to
                  eradicate chlamydia, but for now few
                  experts recommend this. Can cause
                  occasional GI problems and
                  photosensitivity. Good choice if
                  patient is allergic to azithromycin
                  or cost is an issue. Contraindicated
                  during pregnancy.
erythromycin base Generally not recommended because it
                  is less effective and causes more GI
                  symptoms than the top-tier drugs.
                  Can be used during pregnancy.
erythromycin      Generally not recommended because it
 ethylsuccinate   is less effective and causes more GI
                  symptoms than the top-tier drugs.
                  Can be used during pregnancy.
ofloxacin         As effective as, but no better than,
 (Floxin)         azithromycin or doxycycline. High cost
                  exceeds even azithromycin, and ofloxacin
                  needs the week-long dosing schedule of
                  doxycycline. Contraindicated during pregnancy.
amoxicillin       Not recommended in nonpregnant patients.
                  Despite classification as a "recommended
                  regimen" for chlamydia in pregnant women
                  by the Centers for Disease Control and
                  Prevention, it has no advantages over
                  other drugs that are not
                  contraindicated during pregnancy.
(*.)Cost is based on the average wholesale price
for a 100 unit container, or closest available
size, of the generic formulation, unless
otherwise indicated, in the 1999 Red Book.
(**.)The comments reflect the viewpoints and
expertise of the following sources:
Dr. Alain Joffe, director of adolescent medicine,
Johns Hopkins university, Baltimore.
Dr. Walter E. Stamm, professor of medicine
and head of the division of allergy
and infectious diseases at the
University of Washington, Seattle.
Dr. Harold C. Wiesenfeld, codirector,
STD Program, Allegheny county (Pa.)
Health Department.