Doxycycline is the preferred antibiotic for Rocky Mountain Spotted Fever (RMSF) and Lyme disease in children. It is indicated in anthrax exposure and infection for older children but there is insufficient data to determine an ideal regimen.

Doxycycline, a synthetic tetracycline, inhibits protein synthesis and thus bacterial growth.  It is the antibiotic of choice in treating rickettsial infections and is approved for children over age 8 years in Lyme disease.  Treatment duration is minimally one week for RMSF and 2 to 3 weeks for Lyme disease. The product is available in tablet, capsule, suspension and syrup oral forms as well as in injection vials. Doxycyline is well absorbed orally, but bioavailability is limited by such products as calcium, antacids, zinc, iron, etc. It is well tolerated with adverse effects including nausea, diarrhea, rash and light sensitivity. 

Dental staining has been the primary concern limiting tetracycline use.  Doxcycline binds less to calcium than other tetracyclines and demonstrated no significant staining in one small  controlled comparative study. The CDC has issued treatment guidelines for use with anthrax exposure.  The government has stockpiled oral tablets and directions for preparation (crush and mix with soft food or drink) into a palatable form for young children. The mixture is stable for one day at room temperature and at least six days when refrigerated.

(Buck M. Pediatric Pharmacotherapy 2003; 9(10): 1-3)   --J.O.