Tygacil

Thirty-two rats were randomly assigned to 1 of 4 groups with 8 rats in each group. Group 1 received 1 mg/mL of tigecycline (Tygacil, PFIZER) topically. In one study, 1 mg/mL topical application of doxycycline which is tetracycline derivatives was found effective for inhibiting corneal neovascularization [14 ]. As the systemic dose rates of tigecycline and doxycycline are the same in humans, the dose of topical tigecycline was selected to be the same as the topical drugs application of doxycycline. Group 2 received topical 0.9% saline as a control group. The drops were applied topically twice a day for 7 days. Group 3 rats were treated with a 0.05 mL subconjunctival injection of 1 mg/mL tigecycline. The subconjunctival dose of tigecycline was the same as the topical dose. Group 4 rats were treated on a daily basis with a subconjunctival injection of 0.05 mL 0.9% saline as a control group. The rats were anesthetized prior to the subconjunctival injections. Subconjunctival injections were performed using a 30-gauge needle by using an operating microscope and inserted 2 mm posterior to the limbus at the superior bulbar conjunctiva. Table 1 summarizes the information of the groups.

TGC was donated by the QPS laboratory (Egypt). Ammonium acetate, triethylamine (TEA), ammonium hydroxide, ethylene diamine tetra-acetic acid disodium salt dihydrate (EDTA), and acetic acid were obtained from Merck (Germany). Without additional purification, HPLC-grade ethanol from Merck (Germany) was utilized. A Milli-pore analytical deionization system collected deionized water (Bedford, MA). Tygacil
^® (Pfizer, U.S.A.) lyophilized vial containing fifty milligrams of TGC was purchased from wholesale suppliers during the product's shelf life.

The Quality for pharmaceutical services (QPS) laboratories (Egypt) donated TGC. Ammonium acetate, triethylamine (TEA), ammonium hydroxide, ethylene diamine tetra-acetic acid disodium salt dihydrate (EDTA), and acetic acid were obtained from Merck (Germany). Without additional purification, HPLC-grade ethanol from Merck (Germany) was utilized. A Milli-pore analytical deionization system collected deionized water (Bedford, MA). Tygacil
^® (Pfizer, U.S.A.) lyophilized vial containing 50 mg of TGC was purchased from wholesale suppliers during the product's shelf life.

Tigecycline, TG (Tygacil^®, 50 mg/mL), was obtained from Pfizer Inc., Cairo, Egypt. Gentamicin sulfate, GM (Garamicin^®, 80 mg/mL) was purchased from Memphis, Cairo, Egypt.

Tigecycline, in the form of a powder for preparing solutions for infusion (Tygacil), was obtained from Pfizer (New York, NY, USA), whereas tigecycline-d9, which served as an internal standard (IS) for tigecycline, was obtained from Toronto Research Chemicals (North York, ON, Canada). Five excipients, DM-β-CD (MW = 1331.35 g/mol), HP-β-CD (MW = 1541.54 g/mol), TPGS (MW = 662.9 g/mol), SDOCH (MW = 414.6 g/mol), and C10 (MW = 194.25 g/mol), were purchased from Sigma-Aldrich (St. Louis, MO, USA), whereas TMC (239.70 g/mol) was prepared according to Sieval et al. (1998) [44 (link)]. Chemicals for chromatography, i.e., 1,2-dichloroethane, acetonitrile, formic acid, and water, were obtained from Sigma-Aldrich (St. Louis, MO, USA).