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Table 1 Comparison of oral dosing requirements for representative highly protein bound drugs

From: Pharmacologic rationale for the NK1R antagonist, aprepitant as adjunctive therapy in HIV

Drug (PB %) Class Site of action Effective conc Dose
Clindamycin (95 %) Antimicrobial Respiratory tract, skin, soft tissue, and peritonitis MIC susceptibility: medically significant pathogens
Staphylococcus aureus: 0.016 μg/ml—>256 μg/ml
Streptococcus pneumoniae: 0.002 μg/ml—>256 μg/ml
Streptococcus pyogenes: <0.015 μg/ml—>64 μg/ml
Q6 h
Furosemide (91–99 %) Diuretic Kidney Not well defined; varies based on disease state and desired effect 20–80 mg; repeat 6–8 h as needed; titrated up to 600 mg/d
Naproxen (99 %) Anti-inflammatory Peripheral tissues at site of inflammation Trough plasma concentrations of 13–51 µg/mL at 500 mg Q12 h 250–1000 mg/d depending on indication and severity
Tolbutamide (96 %) Hypoglycemic Pancreas (beta cells) ATP-dependent K+ currents of mouse pancreatic B-cells (patch-clamp technique): in the absence of albumin, tolbutamide blocked currents half maximally at 4.1 µmol/L Initial dose: 1–2 g. Maintenance dose: 0.25–3 g daily
Efavirenz (99.5–99.75 %) Antiretroviral Throughout the body—site of infection and the reverse transcriptase enzyme Plasma concentrations above 2 mg/L appear to suppress HIV replication 600 mg/d
Warfarin* (>98 %) Anticoagulant Blood Effective concentrations influenced by many factors. Titrated based on INR response Doses range from 0.5 mg daily to >20 mg; average dose 4–5 mg/d
Phenytoin (>90 %) Anticonvulsant Brain (motor cortex) The clinically effective serum trough concentration is usually 40 to 80 µmol/L. 300 mg/d
Valproic Acid (90–95 %; saturable) Anti-epileptic, Anticonvulsant Brain The therapeutic range for valproic acid (total) is 50–125 µg/mL Doses vary by indication; average dose 500 mg/d; some patients benefit from doses up to 1000 mg/d
Diazepam+ (98.5 %) Anti-anxiolytic Brain/GABAA receptor Effective plasma concentrations 150–400 ng/mL 2–10 mg 2–4 times a day
  1. * The site of action is the systemic circulation; only drug on the list with a bioavailability of 100 %
  2. + Bioavailability of 93 %; target concentrations <1 µg/mL