Fildox Mechanism of Action

Pharmacology: Pharmacodynamics: Mechanism of Action: Doxofylline is a novel bronchodilator xanthine that differs from theophylline by a dioxalane group in position 7. Like theophylline, Doxofylline's mechanism of action is related to inhibition of phosphodiesterase activities. However, in contrast decreased affinity toward adenosine A1 and A2 receptors which may account for the better safety profile of the drug. Doxofylline is reported to inhibit platelet activating factor (PAF) induced bronchoconstriction and subsequent generation of thromboxane A2 (TXA2). It is also reported to inhibit PAF induced pleural exudation and generation of leukotriene C4 (LTC4) substances. This methylxanthine-induced inhibition of inflammatory response has useful action in the therapy of asthma.
Pharmacokinetics: Absorption: (A) Bioavailability: Oral, Tablets: 62.6%.
(B) Therapeutic Drug Concentration: a. Chronic Bronchitis, 8 to 20 mcg/mL.
(C) Time to Peak Concentration: Oral, tablets: 1.19 hours: a. The steady state is reached within 6 hrs at 9.43 mcg/mL.
(D) Area under the curve.
(E) 69.5 h x mcg/mL, oral administration.
Distribution: (1) Protein Binding: 48%.
(2) Distribution Half-Life: 0.19 hrs.
(3) Volume of Distribution: 1 L/kg.
Metabolism: (A) Kidney: Less than 4% of an administered dose of doxofylline is excreted unchanged in the urine.
(B) Total Body Clearance: 444 to 406 mcg/mL.
(C) Elimination Half-Life: Parent compound: 7 to 10 hrs. (Oral).