1. 2016;19;E1055-E1061Timing of Platelet Rich Plasma Injections During Antithrombotic Therapy
   Review
   Houman Danesh, MD, and Ryan Ravi Ramsook, MD.

The use of platelet rich plasma (PRP) spans across many fields owing to its role in healing and as a natural alternative to surgery. PRP continues to grow however much of the literature is anecdotal or case report based and there is a lack of controlled trials to evaluate standards for PRP. The International Cellular Medical Society (ICMS) has developed guidelines to help with the safe advancement of PRP; however there remains a gap in literature concerning the timing of PRP injections in patients who are on antithrombotic therapy. The importance of an intact platelet surface membrane allows for the appropriate release of the healing bioproteins and growth factors granting PRP therapy its efficacy. This along with the proliferation of differentiated cells, enhancement of collagen synthesis, early angiogenesis and revascularization help promote the benefits of regeneration. The intrinsic and extrinsic pathways of the coagulation cascade are valuable in that disruption of this mechanism or prematurely activated platelets may result in limited efficacy. Anticoagulants and antiplatelet drugs are commonly used in patients who are candidates for PRP. As antithrombotic agents affect platelet stability, they will have an effect on PRP efficacy and must be discontinued at an appropriate time frame prior to injection therapy. Understanding the pharmacokinetics and platelet effects can help guide discussion on the proper timing of discontinuation and resumption of a particular antithrombotic agent. With future research, the establishment of clinical practice guidelines concerning PRP and antithrombotic therapy can help structure safe and efficacious means in which to promote healing and regeneration in a growing patient population.