Drugs causing thrombocytopenia or low platelet count

  By Kottapurath Kunjumoideen MD

     Immune thrombocytopenia (ITP) is a commonest blood disorder that causes thrombocytopenia or low platelet count. Apart from ITP, many drugs can cause thrombocytopenia. Some drugs like anticancer drugs and valproic acid causes dose depended decrease in the number of platelets by myelosuppression. Drugs may also cause thrombocytopenia by immunological mechanisms. Immunological drug induced thrombocytopenia can be caused by the following two mechanisms.

1. This is caused by drug depended binding of Fab part of the pathological IgG with the platelets, causing their destruction. This is exemplified the quinidine group of drugs, and seen with many different types of drugs. Fc portion of the IgG molecule is not involved in the binding
2. In this type the Fab portion of the pathological IgG binds to platelet factor 4 (PF4).When complexed with heparin or other drugs, the Fc portion of the IgG molecule bind to platelet receptors causing platelet activation. Since Fc portion of the IgG is bound to the platelets, they are not available to the Fc receptors of the reticulo-endothelial cells. This may explain, why severe thrombocytopenia is rare in patients with HIT.

List of drugs that causes thrombocytopenia
(anti-neoplastic drugs are not included)

• Quinine/Quinidine group
• Quinine
• Quinidine
• Heparin
• Regular unfractionated heparin
• Low molecular weight heparin
• Gold salts
• Antimicrobials
• Antimony containing drugs
• Stibophen
• Sodium stibogluconate
• Cephalosporins
• Cephamandazole
• Cefotetan
• Ceftazidime
• Cephalothin
• Ciprofloxacin
• Clarithromycin
• Fluconazole
• Fusidic
acid
• Gentamicin
• Nilidixic acid
• Penicillins
• Ampicillin
• Apalcillin
• Methicillin
• Meziocillin
• Penicillin
• Piperacillin
• Pentamidine
• Rifampin
• Sulpha group
• Sulfamethoxazole
• Sulfamethoxypyridazine
• Sulfisoxazole
• Suramin
• Vancomycin
• Anti-inflammatory drugs
• Acetaminophen
• Salicylates
• Aspiring
• Diflunisal
• Sodium amiosalicylate
• Sulfasalazine
• Diclofenac
• Fenoprofen
• Ibuprofen
• Indomethacin
• Meclofenamate
• Mefanamic acid
• Naproxen
• Oxyphebutazone
• Phenylbutazone
• Piroxicam
• Sulindac
• Tolmetin
• Cardiac medications and diuretics
• Digoxin
• Digitoxin
• Amiodarone
• Procainamide
• Alprenolol
• Oxprenolol
• Captopril
• Diazoxide
• Alpha-methyldopa
• Acetazolamide
• Chlorothiazide
• Chlorthalidone
• Furosemide
• Hydrochlorothiazide
• Sprinolactone
• Benzodiazepines
• Diazepam
• Anti-epileptic drugs
• Carbamazepine
• Phenytoin
• Valproic acid
H2-antagonists
• Cimetidine
• Ranitidine
• Sulfonylurea drugs
• Chlorpropamid
• Glibenclamide
• Iodinated contrast agents
• Retinoids
• Isotretinoin
• Etretinate
• Anti-histamines
• Antazoline
• Chlorpheniramine
• Illicite drugs
• Cocaine
• Heroin
• Qunine containment
• Antidepressants
• Amitriptyline
• Desipramine
• Doxepin
• Imipramine
• Mianserine
• Miscellaneous drugs
• Tamoxifen
• Actinomycin-D
• Aminoglutethimide
• Danazole
• Desferrioxamine
• Levamizole
• Lidocaine
• Morphine
• Papaverine
• Ticlopidine

References

1. Drug-Induced Thrombocytopenia A Systematic Review of Published Case Reports: Annals of Internal Medicine. December 1, 1998 vol. 129 no. 11 Part 1 886-890
2. Drug-Induced Immune Thrombocytopenia: NEJM Volume 357:580-587 August 9, 2007 Number 6
3. Drug-induced thrombocytopenia: pathogenesis, evaluation, and management: James N. George1 and Richard H. Aster, ASH Educational book
4. Wintrobe's Clinical Hematology, 12th edition

Did you know?
Immune thrombocytopenic purpupura otherwise known as idiopathic thrombocytopenic purura (ITP) is a blood disorder in which your own platelets are destroyed by antibodies directed against them. The word immune means that the thrombocytopenia or low platelet count results from immune system's involvement in this disorder. Since blood platelets are involved in stoppage of bleeding, ITP blood disorder may be associated with bleeding. The term purpura refers to the purplish-looking spots of the skin and mucous membranes (such as the lining of the mouth) where bleeding has already occurred as a result of decreased platelet. ITP usually occurs in women and may happen as one episode, or several episodes. ITP may occur as a complication of pregnancy.