Mechanism of Action: Inhibits bacterial protein synthesis by binding with the 30S ribosomal subunit. Pharmacodynamics: Tetracyclines produce a combination of concentration and time-dependent killing (AUC:MIC ratio). Pharmacokinetics: Dose of 500mg PO: Cmax: 1.5-5 mcg/mL; Tmax: 2-4 hours; Half-life: 6-12 hours; Volume of distribution: 108 L/kg; Table 3 Adverse Effects: GI: epigastric burning, abdominal discomfort, nausea, vomiting, anorexia, diarrhea, esophagitis, esophageal ulcers, dysphagia, candidal superinfections Teeth and bone: (dose/duration related) yellow discoloration of teeth, which turns into a gray- brown permanent discoloration, hypoplasia of enamel, teeth demineralization, skeletal growth retardation Hepatotoxicity: rare, but fatal; intrahepatic cholestasis, jaundice, azotemia, acidosis, irreversible shock Renal Toxicity: hyperphosphatemia, acidosis, polyuria, polydipsia Photosensitivity and hyperpigmentation: red rash to blistering on sun-exposed areas; photoallergic reactions manifested by paresthesias of hands, feet, nose, photo-onycholysis Auditory: tinnitus, hearing loss Vision: visual disturbances CNS: lightheadedness, dizziness, ataxia, drowsiness, headache Dosage: Oral: 250mg, 500mg capsules Adult dosing (common indications): Acne vulgaris: 250 mg PO q other day to 500 mg PO q24h Bartonellosis: 1-2 g/day divided PO in 2-4 doses Brucellosis: 500 mg PO q6h 4 x 3 plus streptomycin Chlamydia psitacci infection: 1-2 g/day divided PO in 2-4 doses Rickettsial disease: 1-2 g/day divided PO in 2-4 doses Nongonococcal urethritis: 500 mg PO q6h x 7 days
Pediatric dosing: 25-50mg/kg/day in 2 to 4 divided doses OR 0.6-1.2g/m2 in 2 – 4divided doses Table 4 Disease state based dosing: Renal failure: CrCl > 50mL/min: 250mg to 500mg q6h
CrCl 10-50 mL/min: 250mg to 500mg q12h to q24h
Hepatic failure: No dosing changes recommended at this time. Contraindications/Warnings/Precautions: Contraindications: Hypersensitivity to tetracycline antibiotics. Precautions: Usage in newborns, infants, and children less than 8 years of age; risk for tooth discoloration; Renal or liver impairment; Phototoxicity; Veneral disease with suspected coexistent syphilis Drug Interactions: Oral contraceptives: Decreased contraceptive effectiveness Warfarin: Increased warfarin effect Barbiturates, phenytoin, carbamazepine: Decreased serum concentrations of doxycycline Ethanol: Decreased doxycyline serum concentrations Antacids, didanosine, sucralfate, multivitamins: decreased tetracycline absorption Kaolin, bismuth subsalicylate: decreased absorption of tetracycline Food: Decreased absorption of tetracycline Milk: Decreased absorption of tetracycline Table 6 Pregnancy: Category D: Risk established, but benefits may outweigh risk. Monitoring Requirements: Therapeutic: Culture and sensitivities, serum levels, signs and symptoms of infection, white blood cell count Toxic: Hypersensitivity syndrome reaction, serum sickness like reaction or single organ dysfunction – Monitor: CBC, LFTs, urinalysis, urea, creatinine, chest radiograph; Drug-induced lupus: monitor antinuclear antibody and hepatic transaminases; General long-term therapy: Liver and renal function tests, Hematopoietic studies Brand names/Manufacturer: Available by many names and manufacturers
Tentative List of Candidates for Graduation 3rd Term, 2009-2010 Commencement Exercises, July 3, 2010 STUDENT NAME Aban, Ness Sheen T. Abanto, Catherine S. Abanto, Darlyn Robey Q. Abrahan, Andrea Ionica L. Adela, Ronald Joshua R. Agcaoili, Angelique Nicole A. Agtarap Jr., Hector R. Aguasin, Maria Aurora R. Aguila, Gian Paolo R. Aguilar, Gian Marco A. Alapa