بسم الله الرحمن الرحيم 1

Yazdanpanah SBMU 1. Agents Used in Anemias 2. Hematopoietic Growth Factors Dr. Yazdanpanah Pharmacology/Toxicology Dept. Shaheed Beheshti School of Pharmacy 2

Yazdanpanah SBMU Outline Introduction 1.Agents used in Anemia Iron Folic acid Vitamin B12 2.Hematopoietic Growth Factors Erythropoietin Myeloid Growth factors Megakaryocyte Growth factors 3

Yazdanpanah SBMU Introduction 4

Hematopoiesis –Production from undifferentiated stem cells of circulating erythrocytes, platelets and leukocytes –Requires 3 essential nutrients and hematopoietic growth factors –Blood cells play roles in Oxygenation of tissues Coagulation Protection against infections Tissue repair 5

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Yazdanpanah SBMU Deficiency of functional blood cells Anemia Thrombocytopenia Neutropenia 8

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13 The pale hand of a woman with severe anemia (right) in comparison to the normal hand of her husband (left).

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Yazdanpanah SBMU 1. Agents Used in Anemias 1.1 Iron 1.2 Vitamin B Folic acid 15

Yazdanpanah SBMU 2. Hematopoietic Growth Factors 2.1 Erythropoietin 2.2 Myeloid growth factors 2.3 Megakaryocyte growth factors 16

Yazdanpanah SBMU 1. Agents Used in Anemias 17

Yazdanpanah SBMU IRON 18

Yazdanpanah SBMU 1.1 IRON: Basic Pharmacology Iron forms the nucleus of the iron-porphyrin heme ring Iron deficiency –The most common cause of chronic anemia –Leads to pallor, fatigue, exertional dyspnea, etc. –Cardiovascular adaptations to chronic anemia –Formation of small erythrocytes with insufficient hemoglobin: microcytic hypochromic anemia 19

20 The protein's α and β subunits are in red and blue, and the iron-containing heme groups in green. heme Structure of human hemoglobin

Yazdanpanah SBMU 1.1 IRON : Pharmacokinetics Free inorganic iron: extremely toxic An elaborate system for regulating iron absorption, transport and storage Iron reclaimed from catalysis of hemoglobin Only a small amount of iron lost from the body Iron deficiency can develop if … 21

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Yazdanpanah SBMU 1.1 IRON : Pharmacokinetics: Absorption Average diet: mg elemental iron daily Absorption of 5-10% of iron Absorption in duodenum and proximal jejunum Increase in iron absorption in response to: Low iron stores Increased iron requirements 23

Yazdanpanah SBMU 1.1 IRON : Pharmacokinetics: Absorption and Transport Iron in foods –Meat –Vegetables and grains Iron crosses the luminal membrane of the intestinal mucosal cell by 2 mechanisms 24

Figure Absorption, transport, and storage of iron 25

Yazdanpanah SBMU 1.1 IRON : Pharmacokinetics: Storage Storage in: –Intestinal mucosal cells –Macrophages in liver, spleen, bone –In parenchymal liver cells 26

Yazdanpanah SBMU 1.1 IRON : Pharmacokinetics: Elimination No mechanism for excretion Losses account for no more than 1 mg of iron per day Regulation of iron balance achieved by changing intestinal absorption and storage of iron, in response to the body's needs 27

Yazdanpanah SBMU 1.1 IRON : Clinical Pharmacology 1. Indications Treatment or prevention of iron deficiency anemia Iron deficiency –Increased iron requirements –Inadequate iron absorption –Blood loss 28

Yazdanpanah SBMU 1.1 IRON : Clinical Pharmacology 2. Treatment with Oral iron therapy  Drugs as ferrous salts  200 – 400 mg of elemental iron  For 3-6 months after cause correction 29

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Yazdanpanah SBMU 1.1 IRON : Clinical Pharmacology 2. Adverse effects with Oral iron therapy Nausea, epigastric discomfort, abdominal cramps, constipation, and diarrhea Usually dose-related, can often be overcome by lowering the daily dose of iron or by taking the tablets immediately after or with meals Some patients have less severe gastrointestinal adverse effects with one iron salt than another Patients taking oral iron develop black stools 31

Yazdanpanah SBMU 1.1 IRON : Clinical Pharmacology 3. Treatment with parenteral iron therapy –Reserved for patients with documented iron deficiency who: unable to tolerate or absorb oral iron for patients with extensive chronic blood loss who cannot be maintained with oral iron alone: –patients with various postgastrectomy conditions and previous small bowel resection –inflammatory bowel disease –advanced chronic renal disease – malabsorption syndromes 32

Yazdanpanah SBMU 3. Treatment with parenteral iron therapy –Iron dextran (IV, deep IM) Hmw and Lmw forms Advantages of IV administration Adverse effects –Hypersensitivity reaction to the dextran: anaphylaxis »A small test dose –Iron-sucrose (IV) –sodium ferric gluconate complex (IV) Advantages to HMW?? IRON : Clinical Pharmacology

Yazdanpanah SBMU 1.1 IRON : Clinical Toxicity 1.Acute toxicity –Almost exclusively in young children (10 Tabs = Death) –Treatment: Whole bowel irrigation Deferoxamine 2.Chronic toxicity (hemochromatosis) –Deposition of excess iron in heart, liver, etc. –Leads to organ failure and death –Treatment: intermittent phlebotomy, deferoxamine, deferasirox 34

Yazdanpanah SBMU Vitamin B 12 35

Yazdanpanah SBMU A cofactor for several essential biochemical reactions Deficiency: Anemia, GI symptoms and neurologic abnormalities Cause of deficiency: Inadequate supply in the diet: unusual Inadequate absorption of dietary vitamin: relatively common and easily treated 1.2. Vitamin B 12 36

Yazdanpanah SBMU A porphyrin-like ring with a central cobalt atom attached to a nucleotide 1.2. Vitamin B 12 : Chemistry 37

Yazdanpanah SBMU Extrinsic and intrinsic factors Active forms of vitamin in humans Deoxyadenosylcobalamin, methylcobalamin Cyanocobalamin, Hydroxocobalamin: convert to active forms Chief dietary source: Meats, eggs, dietary products 1.2. Vitamin B 12 : Chemistry 38

Yazdanpanah SBMU Average diet: 5 – 30 mcg daily 1-5 mcg: usually absorbed Store primarily in liver ( mcg) Normal daily requirement: 2 mcg Absorbed in the distal ileum after complex with IF By highly-specific receptor-mediated transport system 1.2. Vitamin B 12 : Pharmacokinetics 39

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Yazdanpanah SBMU Deficiency: Malabsorption of vitamin due to 1.Lack of IF 2.Loss or malfunction of the specific absorptive mechanism Nutritional deficiency: strict vegetarians Transport to cells bound to transcobalamin I, II, III Excess: transport to liver for storage 1.2. Vitamin B 12 : Pharmacokinetics 42

Yazdanpanah SBMU 1.2. Vitamin B 12 : Pharmacodynamics 43

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Yazdanpanah SBMU 1.2. Vitamin B 12 : Pharmacodynamics 45

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Yazdanpanah SBMU The most common causes of deficiency: Pernicious anemia Gastrectomy Conditions affecting distal ileum malabsorption syndrome inflammatory bowel disease or small bowel resection 1.2. Vitamin B 12 : Clinical Pharmacology 47

Yazdanpanah SBMU Clinical manifestation of Vitamin deficiency: Neurologic syndrome Megaloblastic Macrocytic anemia Leukopenia, Thrombocytopenia, Hypercelluar bone marrow with an accumulation of megaloblastic erythroid cells Megaloblastic anemia: Vitamin B 12 or Folic acid deficiency 1.2. Vitamin B 12 : Clinical Pharmacology 48

Yazdanpanah SBMU Almost all cases of deficiency: Malabsorption of the vitamin Treatment: Parenteral injection of vitamin Most patients: require life-long treatment Hydroxocobalamin, Cyanocobalamin mcg IM for 1-2 weeks ( mcg IM once a month for life) Oral doses of 1000 mcg of vitamin in pernicious anemia 1.2. Vitamin B 12 : Clinical Pharmacology 49

Yazdanpanah SBMU Folic Acid 50

Yazdanpanah SBMU Reduced forms of folic acid required for essential biochemical reactions that provide precursors for the synthesis of amino acids, purines, and DNA Folate deficiency: not uncommon The deficiency easily corrected by administration of folic acid The folate deficiency: Anemia Implicated as a cause of congenital malformations in newborns May play a role in vascular disease 1.3. Folic Acid 51

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Yazdanpanah SBMU 1.3. Folic Acid: Chemistry 53

Yazdanpanah SBMU The average diet in the USA: µg daily Pregnant women absorb as much as µg of folic acid daily Various forms of folic acid present in a wide variety of plant and animal tissues –The richest sources: yeast, liver, kidney, and green vegetables Normally, 5-20 mg of folates stored in the liver and other tissues 1.3. Folic Acid: Pharmacokinetics 54

Yazdanpanah SBMU Excreted in the urine and stool Destroyed by catabolism Serum levels fall within a few days when intake diminished Body stores relatively low and daily requirements high Folic acid deficiency and megaloblastic anemia: within 1-6 months after stopping the intake of folic acid 1.3. Folic Acid: Pharmacokinetics 55

Yazdanpanah SBMU Unaltered folic acid readily and completely absorbed in the proximal jejunum Dietary folates consist primarily of polyglutamate forms of N 5 -methyltetrahydrofolate Before absorption, all but one of the glutamyl residues of the polyglutamates hydrolyzed –by the enzyme α-1-glutamyl transferase ("conjugase") within the brush border of the intestinal mucosa 1.3. Folic Acid: Pharmacokinetics 56

57 llustration of the brush border membrane of small intestinal villi Duodenum with brush border

Yazdanpanah SBMU The monoglutamate N 5 -methyltetrahydrofolate transported into the bloodstream by –both active and passive transport –widely distributed throughout the body Inside cells, N 5 -methyltetrahydrofolate converted to tetrahydrofolate by the demethylation reaction that requires vitamin B Folic Acid: Pharmacokinetics 58

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Yazdanpanah SBMU Megaloblastic anemia from folate deficiency: microscopically indistinguishable from the anemia caused by vitamin B 12 deficiency Folate deficiency does not cause the characteristic neurologic syndrome seen in vitamin B 12 deficiency Folate status assays for serum folate assays for red blood cell folate 1.3. Folic Acid: Clinical Pharmacology 60

Yazdanpanah SBMU Folic acid deficiency often caused by inadequate dietary intake of folates Development of folic acid deficiency: –Alcohol dependence and liver disease –Pregnant women and hemolytic anemia –Malabsorption syndromes –Renal dialysis –Drugs ?? Maternal folate deficiency Occurrence of fetal neural tube defects (spina bifida) 1.3. Folic Acid: Clinical Pharmacology 61

Yazdanpanah SBMU Parenteral administration rarely necessary Oral folic acid well absorbed even in patients with malabsorption syndromes A dose of 1 mg folic acid orally daily sufficient to: – reverse megaloblastic anemia –restore normal serum folate levels –replenish body stores of folates 1.3. Folic Acid: Clinical Pharmacology 62

Yazdanpanah SBMU Therapy should be continued until the underlying cause of the deficiency removed or corrected Therapy may be required indefinitely for patients with malabsorption or dietary inadequacy Folic acid supplementation to prevent folic acid deficiency should be considered in high-risk patients including: –pregnant women –hemolytic anemia –liver disease –patients on renal dialysis 1.3. Folic Acid: Clinical Pharmacology 63

64 Folic Acid Supplementation From 1998, all products made from enriched grains in the USA were required to be supplemented with folic acid Epidemiologic studies show a strong correlation between maternal folic acid deficiency and the incidence of NTDs such as anencephaly

65 Folic Acid Supplementation Supplemented grains with folic acid associated with a significant (30–75%) reduction in NTD rates The reduction in NTDs is dose-dependent Supplementation of grains in the USA with higher levels of folic acid could result in an even greater reduction in the rate of NTDs Rates of other types of congenital anomalies (heart and orofacial) have fallen after supplementation

Yazdanpanah SBMU 2. Hematopoietic Growth Factors 66

Yazdanpanah SBMU 2. Hematopoietic Growth Factors Glycoprotein hormones that regulate the proliferation and differentiation of hematopoietic progenitor cells in the bone marrow The first growth factors to be identified were called colony-stimulating factors 67

Yazdanpanah SBMU 2. Hematopoietic Growth Factors 2.1 Erythropoietin 2.2 Myeloid growth factors 2.3 Megakaryocyte growth factors 68

Yazdanpanah SBMU Erythropoietin 69

Yazdanpanah SBMU A kDa glycoprotein Recombinant human erythropoietin (rHuEPO, epoetin alfa) IV administration: serum half-life of 4-13 hours in patients with chronic renal failure Darbepoetin alfa: A twofold to threefold longer half-life Methoxy polyethylene glycol epoetin ?? 2.1. Erythropoietin: Chemistry and pharmacokinetics 70

Yazdanpanah SBMU Stimulates erythroid proliferation and differentiation by interacting with specific erythropoietin receptors on red cell progenitors Induces release of reticulocytes from the bone marrow Endogenous erythropoietin primarily produced in the kidney –In response to tissue hypoxia, more erythropoietin produced results in correction of the anemia 2.1. Erythropoietin: P harmacodynamics 71

Yazdanpanah SBMU Normally, an inverse relationship exists between the hematocrit or hemoglobin level and the serum erythropoietin level Exception: anemia of chronic renal failure  Erythropoietin levels usually low  Most likely to respond to treatment with exogenous erythropoietin In most primary bone marrow disorders and most nutritional and secondary anemias Endogenous erythropoietin levels are high 2.1. Erythropoietin: P harmacodynamics 72

Yazdanpanah SBMU Consistently improve the hematocrit and hemoglobin level Usually eliminate the need for transfusions Reliably improve quality of life indices 1. For patients with anemia of chronic renal failure –Oral or parenteral iron –Folate supplementation 2.1. Erythropoiesis-stimulating agents: Clinical Pharmacology 73

Yazdanpanah SBMU 2. Useful for the treatment of anemia due to  Primary bone marrow disorders and secondary anemias including patients with: aplastic anemia and other bone marrow failure states myeloproliferative and myelodysplastic disorders multiple myeloma the anemias associated with chronic inflammation, AIDS, and myelosuppresive cancer chemotherapy 2.1. Erythropoietin: Clinical Pharmacology 74

Yazdanpanah SBMU 3. Other uses used successfully to offset the anemia produced by zidovudine treatment in patients with HIV infection and in the treatment of the anemia of prematurity can also be used to reduce the need for transfusion in high-risk patients undergoing elective, noncardiac, nonvascular surgery; to accelerate erythropoiesis after phlebotomies for autologous transfusion for elective surgery; or for treatment of iron overload 2.1. Erythropoietin: Clinical Pharmacology 75 The most common adverse effects – hypertension and thrombotic complications

Yazdanpanah SBMU Myeloid growth factors 76

Yazdanpanah SBMU Recombinant human G-CSF (rHuG-CSF; filgrastim) Recombinant human GM-CSF (rHuGM-CSF; sargramostim) Pegfilgrastim: – much longer serum half-life than recombinant G-CSF 2.2. Myeloid growth factors: Chemistry and pharmacokinetics 77

Yazdanpanah SBMU Stimulate proliferation and differentiation by interacting with specific receptors found on various myeloid progenitor cells G-CSF –Stimulates proliferation and differentiation of progenitors already committed to the neutrophil lineage –Activates the phagocytic activity of mature neutrophils and prolongs their survival in the circulation –A remarkable ability to mobilize hematopoietic stem cells (increase their concentration in peripheral blood) Use of peripheral blood stem cells rather than bone marrow stem cells for autologous and allogeneic hematopoietic stem cell transplantation 2.2. Myeloid growth factors: Pharmacodynamics 78

Yazdanpanah SBMU GM-CSF –broader biologic actions than G-CSF –stimulates proliferation and differentiation of granulocytic progenitor cells, erythroid progenitors and megakaryocyte progenitors –stimulates the function of mature neutrophils –acts together with interleukin-2 to stimulate T-cell proliferation –locally active factor at the site of inflammation –mobilizes peripheral blood stem cells (significantly less efficacious than G-CSF) Myeloid growth factors: Pharmacodynamics

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Yazdanpanah SBMU G-CSF and pegfilgrastim used more frequently (better tolerated) cause bone pain GM-CSF cause more severe side effects, particularly at higher doses –fever, malaise, arthralgias, myalgias, etc Myeloid growth factors: Toxicity 81

Yazdanpanah SBMU Megakaryocyte growth factors 82

Yazdanpanah SBMU Interleukin-11 (IL-11) A kDa protein The half-life: 7-8 hours: sc injection Oprelvekin recombinant form of interleukin-11 Peptide agonists of thrombopoietin receptor –Romiplostim: sc route –Eltrombopag: oral route 2.3. Megakaryocyte growth factors: Chemistry and pharmacokinetics 83

Yazdanpanah SBMU 2.3. Megakaryocyte growth factors: Pharmacodynamics 84 IL-11 Acts through a specific cell surface cytokine receptor to stimulate the growth of multiple lymphoid and myeloid cells Acts synergistically with other growth factors to stimulate the growth of primitive megakaryocytic progenitors increases the number of peripheral platelets and neutrophils Romiplostim high affinity for the thrombopoietin receptor a dose-dependent increase in platelet count

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Yazdanpanah SBMU The most common adverse effects of interleukin-11 –Fatigue, headache, dizziness, and cardiovascular effects The cardiovascular effects: anemia, dyspnea transient atrial arrhythmias Hypokalemia All of these adverse effects appear to be reversible 2.3. Megakaryocyte growth factors: Toxicity 86