Heme/Onc Drugs Flashcards
Heparin: Mechanism
- cofactor for activation of antithrombrin
- decreased thrombrin
- decreased factor Xa
- Short half life
Heparin: Clinical Use
Immediate anticoagulation for pulmonary embolism, acute coronary syndrome, MI, DVT
- Used during pregnancy (does not cross placenta)
- Follow PTT
Heparin: Toxicity
Bleeding, thrombocytopenia (HIT), osteoporisis, drug-drug interactions.
Antidote for heparin toxicity (not to be confused with HIT)
Protamine sulfate - positively charged molecule that binds negatively charged heparin
Low molecular heparin (e.g. enoxaparin, dalteparin)
act more on factor Xa, have better bioavailability and 2-4 times longer half life
Can be administered subcutaneously and without laboratory monitoring
- Not easily reversible
Lepirudin, Bivalirudin
derivatives of hirudin (anti-coagulant used by leeches)
- inhibit thrombrin
- used as an alternative to heparin for anti-coagulating patients with HIT
Heparin-induced thrombocytopenia
development of IgG antibodies against heparin bound to platelet factor 4 (PF4).
Antibody-heparin-PF4 activates platelets –> thrombosis and thrombocytopenia
Warfarin: Mechanism
interferes with normal synthesis and gamma carboxylation of vitamin K-dependent clotting factors II, VII, IX, and X and proteins C and S.
- BLOCKS Vitamin K
- Metabolized by the cytochrome P-450 pathway
- has effect on EXTRINSIC pathway and increase in PT
- Long half-life
Warfarin: Clinical Use
Chronic anticoagulation (after STEMI, venous thromboembolism prophylaxis, and prevention of stroke in atrial fibrillation).
Follow PT/ INR values
** Don’t use in pregnncy, because unlike heparin, warfarin can cross placents
Warfarin: Toxicity
Bleeding, teratogenic, skin/tissue necrosis, drug-drug interactions
Treatment to reverse warfarin overdose
- Give vitamin K
- For rapid reversal of severe warfarin overdose, give fresh frozen plasma
Heparin
- large anionic, acidic polymer
- given parentally (IV, SC)
- acts on blood
- rapid onset
- activates thrombrin, by decreasing action of IIa (thrombrin) and factor Xa
- lasts for hours
- inhibits coagulation in vitri
- overdose treated with protamine sulfate
- monitor PTT
- doesn’t cross placenta
Warfarin
- small lipid-soluble molecule
- given orally
- acts on liver
- slow onset, limited by half lives of normal clotting factors
- impairs synthesis of vitamin K-dependent clotting factors (II, VII, IX, X, proteins C and S)
- Vitamin K antagonist
- Lasts for DAYS
- overdose treated with IV Vitamin K or fresh frozen plasma
- Monitor extrinsic pathway (PTT/INR)
- Teratogenic
Thrombolytics
Altepase (tPa), reteplase (rPA), tencteplase (TNK-tPA)
Thrombolytic: Mechanism
Directly or indirectly aid conversion of plasminogen to plasmi, which cleaves thrombin and fibrin clots.
Increases PT and PTT. NO CHANGE IN PLATELETS
Thrombolytics (“-eplase”): Clinical Use
Early MI, early ischemic stroke, direct thrombolysis of severe pulmonary embolism
Thrombolytics (“-eplase”): Toxicity
Bleeding.
Contraindicated in patients with active bleeding, history of intracranial bleeding, recent surgery, known bleeding diathesis, or severe hypertension
Tx of thrombolytic (“-eplase”) toxicity:
Aminocaproic acid - inhibitor of fibrinolysis
Aspirin: Mechanism
IRREVERSIBLY inhibits cyclooxygenase (both COX-1 and COX-2) enzyme by covalent acetylation.
Platelets cannot synthesize new enzyme, so effect lasts until new platelets are produce
- Increased bleeding time, decreased thromboxane and prostaglandins
- NO EFFECT on PT and PTT
Aspirin: Clinical Use
Antipyretic, analgesic, anti-inflammatory, antiplatelet (decreased aggregation)
Aspirin: Toxicity
Gastric ulceration, tinnitus (CN VIII).
Chronic used can lead to acute renal falire, interstitial nephritis, and upper GI bleeding
** Reye’s syndrome in children with with viral effection
Treatment of Apsitin toxicity
N-acetylation -
Aspirin toxicity is respiratory alkaltois and metabolic acidosis
ADP receptor inhibitos
Clopidogrel, Ticlipidine, Prasugrel, Ticagrelor
ADP Receptor Inhibitor: Mechanism
Inhibit platelet AGGREGATION by irreversibly binding ADP receptors. Inhibit fibrinogen binding by preventing glycoprotein IIb/IIIa from binding to fibrinogen
ADP receptor inhibitor: Clinical Use
Acute coronary syndrome
Coronary stenting
Decreased incidence or recurrence of thrombotic stroke
ADP Receptor Inhibitior: Toxicity
Neutropenia (ticlopidine)
Cliostazol, Dipyridamole: Mechanism
Phosphodiesterase III inhibitor;
Increased cAMP in platelets, thus inhibiting platelet aggregation
Vasodilators
Cliostazol, Dipyridamole: Clinical Use
Intermittent claudication, coronary vasodilation, prevention of stroke or TIAs (combined with aspirin), angina prophylaxis
Cliostazol, Dipyridamole: Toxicity
Nausea, headache, facial flushing, hypotension, abdominal pain
GP IIb/IIIa inhibitors
Abciximab, Eptifibatide, Tirofiban
GP IIb/IIIa Inhibitors (Abciximab, Eptifibatide, Tirofiban): Mechanism
Bind to the glycoprotein receptor IIb/IIa on activated platelets, preventing aggregation.
Abciximab is made from monoclonal antibody Fab fragments
GPIIb/IIIa inhibitors (Abciximab, Eptifibatide, Tirofiban): Clinical USe
Acute coronary syndromes, percutaneous transluminal coronary angioplasty
GPIIb/IIIa inhibitors (Abciximab, Eptifibatide, Tirofiban)
Bleeding, thrombocytopenia
Methotrexate (MTX): Mechanism
Folic acid analog that inhibits dihydrofolate reductase –> less dTMP –> less DNA and less protein synthesis
Methotrexate (MTX): Clinical Use
Cancers: leukemias, lymphomas, choriocarcinoma, sarcomas
Non-neoplastic: abortion, ectopic pregnancy, rheumatoid arthritis, psoriasis
Methotrexate (MTX): Toxicity
Myelosuppression, which is reversible with leucorvorin (folinic acid) “rescue”
Macrovesicular fatty chain in liver
- Mucositis
- Teratogenic
5-Fluorouracil (5-FU): Mechanism
Pyrimadine analog bioactivated to 5F-dUMP which covalently complexes folic acid.
This complex inhibits thymidylate synthase –> dTMP –> less DNA and protein synthesis
5-Fluorouracil (5-FU): Clinical Use
Colon cancer, basal cell carcinoma (topical)
5-Fluorouracil (5-FU): Toxicity
Myelosuppression, which is NOT reversible with leucorvorin
Overdose: “rescue” with thymidine
Photosensitivity
Cytarabine (arabinofuranoysl cytidine): Mechanism
Pyrimidine analog –> inhibition of DNA polymerase
Cytarabine: Clinical Use
Leukemias, lymphomas
Cytarabine: Toxicity
Leukopenia, thrombocytopenia, megaloblastic anemia
Azathoprine ; 6-mercaptopurine; 6-thioguanine : Mechanism
Purine (thiol) analogs –> decreased de novo purine synthesis
- Activated by HGPRT
Azathoprine; 6-mercaptopurine; 6-thioguanine: Clinical Use
Leukemias
Azathoprine; 5-mercaptopurine; 6-thioguanine: Toxicity
Bone marrow, GI, liver
Metabolized by xanthine oxidase –> thus increase toxicity with allopurinol
Dactinomycin (actinomycin D): Mechanism
Intercalates in DNA
Dactinomycin (actinomycin D): Clinical Use
Wilm’s tumor, Ewing’s sarcoma, rhabdomyosarcoma
Used for childhood tumors (“children ACT out”)
Dactinomycin (actinomycin D): Toxicity
Myelosuppression
Doxorubicin (Adriamycin), Daunorubicin: Mechanism
Generate free radicals
Noncovalently interalate in DNA –> breaks in DNA –> decreased replication
Doxorubicin (Adriamycin), Daunorubicin: Clinical Use
Solid tumors, leukemias, lymphomas
Doxorubicin (Adriamycin), Daunorubicin: Toxicity
Cardiotoxicity (dilated cardiomyopathy), myelosuppression, Alopecia
Toxic to tissues following extravasation
Dexrazozane (Fe chelating agent), used to prevent cardiotoxicity
Bleomycin: Mechanism
Induces free radical formation , which causes breaks in DNA
Bleomycin: Clinical Uses
Testicular cancer, Hodgkin’s lymphoma
Bleomycin: Toxicity
Pulmonary fibrosis, skin changes.
Minimal myelosuppression
Cyclophosphamide; Ifosfamide: Mechanism
Covalently X-link (interstrand) DNA at guanine N-7. Require bioactivation by liver
Cyclophosphamide; Ifosfamide: Clinical Use
Solid tumors, leukemia, lymphomas, and some brain cancers
Cyclophosphamide; Ifosfamide: Toxicity
Myelosuppression;
Hemorrhagic cystitis, partially prevented with mesna (thiol group of mesna binds toxic metabolite)
Nitrosoureas (carmustine, lomustine, semustine, streptozocin): Mechanism
Alkylating agent
Require bioactivation
Cross blood-brain barrier –> CNS
Nitrosoureas (carmustine, lomustine, semustine, streptozocin): Clinical Use
Brain tumors (including glioblastoma multiforme)
Nitrosoureas (carmustine, lomustine, semusine, streptozocin): Toxicity
CNS toxicity (dizziness, ataxia)
Bulsulfan: Mechanism
Alkylates DNA
Bulsulfan: Clinical Use
CML. Also used to ablate patient’s bone marrow before bone marrow before transplantation
Bulsulfan: Toxicity
Pulmonary fibrosis, hyperpigmentation
Vincristine, Vinblastine: Mechanism
Alkaloids that bind to tubulin in M phase and block polymerization of microtubules so that mitotic spindle cannot form.
“Microtubules are the vines of your cells”
Vincristine, Vinblastine: Clinical Use
Solid tumors, leukemias, and lymphomas
Vincristine, Vinblastine: Toxicity
Vincristine - nephrotoxicity ( areflexia, peripheral neuritis), paralytic ileus
Vinblastine - myelosuppression
Paclitaxel, other taxols: Mechanism
Hyperstabilize polymerized microtubules in M phase so that mitotic spindle cannot breakdown (anaphase cannot occur)
Paclitaxel, other taxols: Clinical Use
Ovarian and breast carcinomas
Paclitaxel, other taxols: Toxicity
Myelosuppression and hypersensitivity
Cisplatin, carboplatin: Mechanism
Cross-link DNA
Cisplatin, carboplatin: Clinical Use
Testicular, bladder, ovary, and lung carcinomas
Cisplatin, carboplatin: Toxicity
Nephrotoxicity and acoustic nerve damage. Prevent nephrotoxicity with amifostine (free radical scavenger) and chloride diuresis
Etoposide, Tenoposide: Mechanism
Inhibit DNA topoisomerase II –> increased DNA degradation
Etoposide: Tenoposide: Clinical Use
Solid tumors, leukemias, lymphomas
Etoposide, Tenoposide: Toxicity
Myelosuppression, GI irritation
Hydroxyurea: Mechanism
Inhibits ribonucleotide reductase –> less DNA Synthesis (S phase specific)
Hydroxyurea: Clinical Use
Melanoma, CML, sickle cell disease (increase HbF)
Hydroxyurea: Toxicity
Bone marrow suppression, GI upset
Prednisone, Prenisolone: Mechanism
May trigger apoptosis. May even work on non-dividing cells.
Prednisone, Prenisolone: Clinical Use
Most commonly used glucocorticoid in cancer chemotherapy. Used in CLL, non-Hodgkin’s lymphoma (part of combination chemotherapy regimen).
- Also used as an immunosuppressant (e.g. autoimmune disease)
Prednisone, Prenisolone: Toxicity
Cushing-like symptoms; immunosuppression, cataracts, acne, osteoporosis, hypertension, peptic ulcers, hyperglycemia, psychosis
Tamoxifen, Raloxifene: Mechanism
SERMs- receptor antagonist in breast and antagonist in bone. Block the binding of estrogen to estrogen-positive cells
Tamoxifen, Raloxifene: Clinical Use
Breast cancer treatment and prevention. Also useful to prevent osteoporosis
Tamoxifen Toxicity
Partial agonist in endometrium, which increases risk of endometrial cancer , “hot flashes”
Raloxifene: Toxicity
No increased risk of endometrial cancer because it is an endometrial antagonist
Trastuzumab (Herceptin): Mechanism
Monoclonal antibody against HER-2 (cerbB2), tyrosine kinase. Helps kill breast cancer that overexpress HER-2, possibly through antibody-dependent cytotoxicity
Trastuzumab (Herceptin): Clinical Use
HER-2 positive breast cancer
Trastuzumab (Herceptin): Toxicity
Cardiotoxicity
Imatinib (Gleevac): Mechanism
Philadelpha chromosome bcl-acr tyrosine kinase inhibitor
Imatinib (Gleevac): Clinical Use
CML, GI stromal tumors
Imatinib (Gleevac): Toxicity
Fluid retention
Rituximab: Mechanism
Monoclonal antibody against CD20, which is found in B cell neoplasms
Rituximab: Clinical Use
Non-Hodgkin’s lymphoma, rheumatoid arthritis (with methotrexate)
Vemurafenib: Mechanism
Small molecule inhibitor of forms of B-RAF kinase with V600E mutation
Vemurafenib: Clinical Use
Metastatic melanoma
Bevacizumab: Mechanism
Monoclonal antibody against VEGF angiogenesis
Bevacizumab: Clinical Use
Solid tumors
Cisplatin/Carboplatin Toxicity
Acoustic nerve damage (and nephrotoxicity)
Vinecristine: toxicity
Peripheral neuropathy
Belomycin, Busulfan: Toxicity
Pulmonary fibrosis
Doxorubicin: Toxicity
Cardiotoxicity
Trastuzumab: Toxicity
Cardiotoxicity
Cyclophosphamide
Hemorrhagic cystitis
5-FU and 6-MP: Toxicity
Myelosuppression
Methotrexate: Toxicity
Myelosuppression