Sustained-Release Formulation of Doxycycline Hyclate for Prophylaxis of Tick Bite Infection in a Murine Model of Lyme Borreliosis

Abstract

The prophylactic potential of a single injection of sustained-release doxycycline hyclate (Atridox) was compared to that of a single oral dose of doxycycline hyclate in a murine model of Lyme borreliosis. Prophylaxis, as measured by the lack of cultivable spirochetes and demonstrable pathology, was noted for 43% of orally treated mice; in contrast, the sustained-release doxycycline hyclate completely protected mice from infection and resultant pathology.Since Lyme borreliosis became a reportable disease in 1982, it has consistently been the most common vector-borne disease reported in the United States (3). Given the lack of an available vaccine, the prophylaxis of tick bite infection consists of personal protective measures directed against ticks in areas where Borrelia burgdorferi is endemic (4). Reports on the efficacy of post-tick exposure antimicrobial prophylaxis in animals and humans demonstrate a high degree of variability, and opinions vary greatly as to the necessity of such prophylactic treatment (5,11,16,17,19). The need for effective prophylaxis is underscored by the increase in cases of Lyme disease and the seriousness of untreatable sequelae in a subset of infected individuals (7,8). This study compares the effectiveness of a single oral dose of doxycycline hyclate, designed to mimic levels in the plasma of humans given 200 mg orally (6,14), to that of a subcutaneous injection of sustained-release doxycycline (Atridox; Atrix Laboratories, Fort Collins, Colo.) in a mouse model of Lyme borreliosis (22).Laboratory-reared nymphal ticks (Ixodes scapularis) that were raised as previously described (13) and that have previously been shown to be free of Anaplasma phagocytophila and Babesia microti (2, 21) were infected with B. burgdorferi strain B31. Five infected ticks were placed on the heads and neck areas of specific-pathogen-free, 7-week-old female C3H/HeJ mice (Jackson Laboratories, Bar Harbor, Maine). Seventy-two hours after tick infestation, the partially engorged ticks were removed from all of the mice. Since three or four infected ticks (average, 3.4) fed on each mouse, the mice were then randomly assigned to receive 2 mg of oral doxycycline hyclate in water, 4.2 mg of a sustained-release doxycycline hyclate copolymer formulation (Atrix Laboratories), or a water or poly (DL-lactide) in N-methyl-2-pyrrolidone copolymer (Atrix Laboratories) control. The oral doxycycline or water vehicle was delivered by gavage in 0.1 ml of tissue-grade water. Sustainedrelease doxycycline hyclate was mixed according to the manufacturer's instructions and transferred to a 1-ml Luerlock syringe (Becton Dickinson, Chicago, Ill.) fitted with a 25-gauge needle for subcutaneous injection. A total of 0.05 ml was delivered to each mouse. At 4 weeks posttreatment, an ear biopsy was obtained and cultured in Barbour-Stoenner-Kelly medium (15) to determine B. burgdorferi infection status (18). The mice were euthanized (by exposure to CO 2 ) 8 weeks after tick infestation, and heart and bladder tissues were placed in culture me...

Ineffectiveness of Tigecycline against Persistent Borrelia burgdorferi

“…These studies have shown success with a variety of different classes of antimicrobial drugs (31,33,34,41,44,50,53,56,82). However, with the advent of increasingly sensitive PCR methods, studies in mice and dogs have revealed persistence of noncultivatable spirochetes, based upon DNA amplification, in tissues following antibiotic treatment (13,27,69,70).…”

Efficacy of an Experimental Azithromycin Cream for Prophylaxis of Tick-Transmitted Lyme Disease Spirochete Infection in a Murine Model

“…Single-dose oral doxycycline given by gavage has resulted in disappointing levels of prophylaxis, demonstrating 20% to 43% protection (15,16). In contrast, a slowrelease injectable doxycycline gel that continues to release doxycycline into the bloodstream over several weeks gave 100% protection (15).…”

“…Antibiotic prophylaxis has been delivered to mice via oral gavage (15,16,17), an injectable slow release formulation (15,16), or topical applications (18,19,20). In the current study, the efficacy of topical creams containing doxycycline was compared to that of creams containing azithromycin.…”

Elimination of Borrelia burgdorferi and Anaplasma phagocytophilum in Rodent Reservoirs and Ixodes scapularis Ticks Using a Doxycycline Hyclate-Laden Bait

“…14,15 Approximately 300 μL whole blood were collected in microtainers containing EDTA and centrifuged, and the plasma was run over a Beckman System Gold high-pressure liquid chromatograph (Beckman Coulter, Fullerton, CA); associated 32-Karat version 5.0 software was used combined with a C 18 column (100 × 4.6-mm inside diameter; Alltech, Deerfield, IL).…”

“…Serum was subsequently used to determine pharmacokinetic levels of doxycycline hyclate in small-mammal plasma by high-pressure liquid chromatography (HPLC). 15 Animals were ear-tagged (Monel Model 1005-1 or 1005-3; National Band and Tag Company, Newport, KY) and weighed, their overall body measurements were recorded (total body length, tail length, right ear length, and right hind foot length), and subsequently, they were released at the point of capture. 11 Small mammals recaptured during a particular trapping event were not reprocessed.…”