TABLE 1.

Treatment efficacy of sustained-release doxycycline hyclate by subcutaneous injection versus oral administration of doxycycline hyclate^a

Treatment or control	No. of mice infected/total no. testedb	Level of protection (%)c
Oral doxycycline hyclate	7/13	43
Water control	15/16	NA
Sustained-release doxycycline hyclate	0/12	100
Copolymer controld	10/12	NA

^aMice received either a single oral dose of 2 mg of doxycycline hyclate or a single subcutaneous injection of 4.2 mg of sustained-release doxycycline hyclate 72 h after tick infestation. Cultures of ear biopsies were taken 4 weeks postinfestation; bladder and heart tissues were cultured 8 weeks postinfestation.

^bFisher's test results were as follows: for values for the oral doxycycline hyclate treatment compared with those for the water control treatment, P was 0.02; for values for the sustained-release doxycycline hyclate treatment compared with those for the copolymer control treatment, P was 0.0001; for values for the sustained-release doxycycline hyclate treatment compared with those for the oral doxycycline hyclate treatment, P was 0.005; and for values for the water control treatment compared with those for the copolymer control treatment, P was 0.56.

^cNA, not applicable.

^dPoly(dl-lactide) in N-methyl-2-pyrrolidone was used as the copolymer control.