Platelets

(USAN, rINN)

💊 Chemical information

Plaquetas.

Pharmacopoeias.

Many pharmacopoeias have monographs, including US.

USP 31 (Platelets). The portion of blood that contains platelet cells derived from human whole blood from which red blood cells and a portion of the plasma are removed by centrifugation, sedimentation, or apheresis. Platelets derived from whole blood may be pooled from multiple donors to form one dose of platelets. The source blood for platelets must be tested for syphilis, hepatitis B, human T-cell lymphotropic virus (HTLV) Type I and Type II, hepatitis C, and HIV Type 1 and Type 2. Platelets derived from whole blood should have a minimum of 5.5 × 10 10 platelet cells suspended in a volume of 40 to 70 mL of original plasma. Platelets produced by apheresis should have a minimum of 3.0 × 10 11 platelet cells suspended in 100 to 500 mL of original plasma or in an approved additive solution. Platelets derived from whole blood or by apheresis may be further processed by filtration for removal of leucocytes, or by irradiation to inactivate lymphocytes. The names of the different platelet preparations are:
Platelets—prepared from a single unit of whole human blood within 8 hours of collection
Platelets, Pooled—individual platelet units derived from whole human blood and pooled by aseptic techniques, labelled with a unique identifying number related to the number of individual units pooled, and with an expiry date of 4 hours after pooling of the individual units
Platelets, Pheresis—prepared by apheresis from a single donor
Platelets, Leukocyte Reduced—prepared from whole blood, either by centrifugation or by sedimentation, and filtered to yield less than 8.3 × 10 5 white blood cells in the final container
Platelets, Pheresis, Leukocyte Reduced—contains less than 5 × 10 6 white blood cells, prepared by apheresis, with or without a filter Platelets may be stored in plasma or in an approved additive solution at 20° to 24° with continuous gentle agitation for no more than 5 days after date of preparation. The pH must be greater than 6.2 throughout the storage period.

USP 31 (Platelet Concentrate). It contains the platelets taken from plasma obtained, in a single procedure, by whole blood collection, plasmapheresis, or plateletpheresis from a single suitable human donor. The platelets are suspended in a specified volume (20 to 30 mL, or 30 to 50 mL) of the original plasma. The suspension contains not less than 5.5 × 10 10 platelets per unit in not less than 75% of the units tested. It should be stored in hermetically-sealed sterile containers at 20° to 24° (30 to 50 mL volume), or at 1° to 6° (20 to 30 mL volume) except during transport when the temperature may be 1° to 10°. The expiration time is not more than 72 hours from the time of collection of the source material. Continuous gentle agitation must be maintained if stored at 20° to 24°. The suspension must be used within 4 hours of opening the container and should be administered with equipment that contains a filter.

💊 Adverse Effects and Precautions

Transmission of infection has been associated with the transfusion of blood products including platelets. Since platelets are stored at room temperature there is increased risk of bacterial infection after transfusion. Transfusion reactions including fever and urticaria are not uncommon. Recipients of multiple transfusions of platelet concentrates from random donors may develop antibodies to HLA which result in impaired responsiveness to subsequent transfusions. Use of leucocyte-depleted platelet concentrates reduces the incidence of transfusion reactions and of HLA sensitisation. Platelet concentrates prepared from Rh(D)-positive donors should generally not be given to Rh(D)-negative women of child-bearing potential. Ideally platelet concentrates should also be ABO-compatible with the recipient.

ABO compatibility.

Platelets express the ABO blood group antigens and the plasma component of platelet concentrates may contain alloantibodies from the donor. Ideally, ABO-identical platelet concentrates should be used, but ABO-compatible concentrates are often used and incompatible concentrates may be used in an emergency. However, the use of ABO-mismatched platelets can reduce the efficacy of the platelet transfusion. Also, acute haemolytic reactions can occur after infusion of mismatched platelets if the infused plasma contains high antibody titres or the volume of plasma infused is large. Some have suggested that screening donors for high antibody titres should be routine in order to avoid this, but there is no consensus as to the definition of critical titre. There have been mixed reports on whether the use of ABO-mismatched platelets has an effect on the recipient’s long-term clinical course. Reviews.
1. Lozano M, Cid J. The clinical implications of platelet transfusions associated with ABO or Rh(D) incompatibility. Transfus Med Rev 2003; 17: 57–68.

HLA antibodies.

Platelets obtained from single donors have been used in patients receiving multiple transfusions of platelet concentrates to reduce the formation of antibodies to HLA. Some practitioners suggest1 that patients who are likely to need long-term platelet support should be typed for HLA A and B antigens and screened for

HLA antibodies.

Leucocyte-depleted platelets and UVB-irradiated platelets have also been tried. A study2 in 530 patients found that the incidence of platelet refractoriness was reduced from 13% of those patients receiving pooled platelet concentrates to 3% and 5% of those receiving leucocyte-depleted and UVB-irradiated platelets, respectively. A meta-analysis3 of this and earlier small studies also concluded that leucocyte depletion reduced the risk of alloimmunisation and platelet refractoriness. Some guidelines4 have nonetheless considered that there is no convincing evidence of clinical benefit from routine use.
1. Dan ME, Schiffer CA. Strategies for managing refractoriness to platelet transfusions. Curr Hematol Rep 2003; 2: 158–64
2. The Trial to Reduce Alloimmunization to Platelets Study Group. Leukocyte reduction and ultraviolet B irradiation of platelets to prevent alloimmunization and refractoriness to platelet transfusions. N Engl J Med 1997; 337: 1861–9
3. Vamvakas EC. Meta-analysis of randomized controlled trials of the efficacy of white cell reduction in preventing HLA-alloimmunization and refractoriness to random-donor platelet transfusions. Transfus Med Rev 1998; 12: 258–70
4. British Committee for Standards in Haematology, Blood Transfusion Task Force. Guidelines on the clinical use of leucocytedepleted blood components. Transfus Med 1998; 8: 59–71. Also available at: http://www.bcshguidelines.com/pdf/trans129.pdf (accessed 27/10/05)

💊 Uses and Administration

Blood platelets assist in the haemostatic process by aggregating to form a platelet thrombus, and by releasing factors involved in initiating coagulation. Transfusions of platelet concentrates are given to patients with thrombocytopenic haemorrhage. They are also given prophylactically to reduce the frequency of haemorrhage in thrombocytopenia associated with the chemotherapy of neoplastic disease.
1. Fresh-frozen Plasma, Cryoprecipitate, and Platelets Administration Practice Guidelines Development Task Force of the College of American Pathologists. Practice parameter for the use of fresh-frozen plasma, cryoprecipitate, and platelets. JAMA 1994; 271: 777–81
2. Brozović B, et al. Platelet and granulocyte transfusions. In: Contreras M, ed. ABC of transfusion. 3rd ed. London: BMJ Books, 1998: 17–22
3. Schiffer CA, et al. Platelet transfusion for patients with cancer: clinical practice guidelines of the American Society of Clinical Oncology. J Clin Oncol 2001; 19: 1519–38. Also available at: http://www.jco.org/cgi/reprint/19/5/1519.pdf (accessed 27/10/05
4. British Committee for Standards in Haematology, Blood Transfusion Task Force. Guidelines for the use of platelet transfusions. Br J Haematol 2003; 122: 10–23. Also available at: http:// www.bcshguidelines.com/pdf/platelettrans040703.pdf (accessed 27/10/05
5. Heal JM, Blumberg N. Optimizing platelet transfusion therapy. Blood Rev 2004; 18: 149–65
6. Stroncek DF, Rebulla P. Platelet transfusions. Lancet 2007; 370: 427–38.

💊 Preparations

USP 31: Platelet Concentrate; Platelets.
Published December 18, 2018.