The Food and Drug Administration (FDA) is an agency of the United States Department of Health and Human Services. One of a FDA approved prescribed medication is lovenox. It is one of an important drug being utilized on our cardiac-neuro unit. Pharmacokinetics is defined as the study of the time course of drug absorption, distribution metabolism, and excretion. Pharmacodynamics refers to the relationship between drug concentration at the site of action and the resulting effect, including the time course and intensity of therapeutic and adverse effects. Enoxaparin is a low molecular weight heparin which has antithrombotic properties.
Pharmacodynamics- In humans, enoxaparin given at a dose of 1.5 mg/kg subcutaneously (SC) is characterized by a higher ratio of anti-Factor Xa to anti-Factor IIa activity. And the increase was seen based on thrombin time and the activated partial thromboplastin time. Enoxaparin at a 1 mg/kg dose, administered SC every 12 hours resulted in aPTT values of 45 seconds or less. A 30 mg IV bolus immediately followed by a 1 mg/kg SC administration resulted in aPTT of 50 seconds.
Pharmacokinetics-Enoxaparin acts primarily by increasing antithrombin III.This in turn, reduces thrombin generation, decrease conversion of fibrinogen to fibrin, thereby inhibiting fibrin clot formation. The medication is absorbed rapidly and completely. It is weakly metabolized by de-sulfation and de-polymerization. The half-life is 4.5 hours after subcutaneous administration. The peak effect is 3 to 5 hours following subcutaneous injection. The time course of injections up to 24 hours following subcutaneous injection. The eliminations is done through kidneys.
Pharmacodynamics and Pharmacokinetics in different groups-The clearance following single SC dosing were slightly higher in males than in females. The clearance following single and multiple SC dosing in geriatric subjects were close to those observed in young subjects. When non-weight adjusted dosing was administered, it was found after a single-subcutaneous 40 mg dose, that anti-Factor Xa exposure is 52% higher in low-weight women and 27% higher in low-weight men. Also, the time to peak concentration and the half-life of enoxaparin may be prolonged in elderly patients. Apparent clearance is decreased approximately 30% in patients with chronic, severe renal failure. The pharmacokinetics of enoxaparin sodium are significantly different during pregnancy. The observed difference is likely because of increased renal clearance of enoxaparin during pregnancy.
Adverse effects-The use of enoxaparin is not recommended for thromboprophylaxis in pregnant women with prosthetic heart valves. Pregnant women receiving enoxaparin should be carefully monitored and apprised of the potential hazard to the fetus and the mother. Appropriate studies on the relationship of age to the effects of enoxaparin have not been performed in the pediatric population. Lovenox does not cross the placenta, and is not expected to result in fetal exposure to the drug. It is not known whether enoxaparin is distributed into breast milk. Elderly patients, especially females, may be more susceptible than other patients to bleeding during enoxaparin therapy. The risk of associated bleeding and serious adverse events increases with age. References
-Enoxparin(systematic). drugs.com. Retrieved from -http://www.drugs.com/mmx/enoxaparin.html.
-Introduction to Pharmacokinetics and Pharmacodynamics. . Retrieved from http://www.ashp.org
Lovenox (enoxaparin sodium) injection-Cardinal health. (2013, April). US National Library of Medicine. Retrieved from http://dailymed.nlm.nih.gov/dailymed/lookup.cfm