Anti anaemic Drugs

Anti anaemic DrugsHaematopoiesis: it is the production of erythrocytes,

platelets, and leukocytes from undifferentiated stem cells.The haemtopoietic machinary reside in the bone marrow in

adults.It requires a constant supply of essential nutrients – iron,

cyanocobalamine, folic acid and presence of hematopoietic growth factors

Anti anaemic DrugsAnemia: anemia is a common clinical condition that is caused by an acquired or hereditary abnormality of RBCS or its precursor, or it may be a manifestation of an underlying non hematologic disorder.anemia is defined as a decrease in the circulating RBC mass; the usual criteria are a Hb of less than 11.5 G/dl in women and less than 14 G/dl in men.

Anti anaemic DrugsSigns and Symptoms:Patients with a Hb less than 7G/dl will have symptoms of tissue hypoxia (fatigue, headache, dyspnea, pallor, angina, tachycardia, visual impairment, syncopy, lymphadenopathy, hepatic and or splenic enlargement, bone tenderness, blood loss in feces, neurologic symptoms.

Anti anemic DrugsClassification of anemia:1.anemia associated with decrease RBC production for e.g..A) iron deficiency anemia, B) megaloblastic anemiaC) ThalassemiaD) anemia due to chronic disease and renal failure.2. Anemia due to increased RBC destruction:Haemolytic anemia sickle cell anemia

Anti anaemic Drugs1- Iron: Total quantity of iron in the body is 4-5G 65-70% in the form of Hb in RBC 4% in myoglobin 1% in various heme compound 15-30% stored in the form of ferritin and hemosiderin in RE system, liver, spleen, intestinal mucosa and bone marrow

Anti anaemic DrugsIron is required for Hb production. in the absence of adequate iron, small red cells with insufficient

Hb are formed, giving rise to microcytic hypochromic anemia.

Iron deficiency occur due to: (a) inadequate dietary intake as in vegetarians, malnourished pts. (b) due to blood loss a in women in heavy menstruation (c) when iron requirement is increased as in pregnancy and in

growing children. (d) acute or chronic blood loss

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Anti anaemic Drugs2, 3- cyanocoblamine and folic acid: are required for normal DNA synthesis. Deficiency of either of these vitamins results in impaired production and abnormal maturation of RBCS giving rise the characteristic blood and bone marrow picture known as megaloblastic anemia4- Erythropoeitin and colony stimulating factors are hormones that regulate blood cell development and proliferation in the bone marrow.

Anti anaemic Drugs1- Iron preparation:Oral ironParenteral iron

A- oral iron A) Ferrous sulfate - 325mg - 65mg elemental ironB )Ferrous gluconate - 320mg -37mg elemental ironC) Ferrous fumarate - 325mg - 106mg elemental iron

B- Parenteral iron: iron dextran 50mg elemental iron/ml

Anti anaemic DrugsPharmacokinetics: Absorption: iron (Fe++; more readily absorbed) absorb from duodenum and upper jejenum Fe+++ (ferric) in →the intestinal mucosal cell.Ferric iron binds with transferrin in plasma and transported in other tissues and stored as ferritin and hemosiderin form.About 10 -20% of dietary iron is absorbed, for e.g. a standard diet if contain 10-15mg of iron, only 1mg is absorbed. Absorption when iron requirement is as in ↑ ↑pregnancy, menstruation, growing children

Abs is increased by: glucose, amino acids & ascorbic acid.

& decreased by : phosphate bicarbonate bile acids, antacids & tetracycline.

Heme iron in meat Hg & myoglobin can be absorbed intact.

Iron in vegetables & grains, tightly bound to organic cpds; < available for abs.

Anti anaemic DrugsDistribution: ferric from iron store sites through transferrin goes in the RBCS.200- 400 mg oral elemental iron daily should be given to correct anemia (27% absorbed ,so 50-100mg iron can be incorporated in Hb).Treatment should be continued for 3-6 months, this not only to correct the anemia but will replenish iron stores. (Hb should reach normal level in 1-3 months). Failure to respond to oral iron therapy may be due to incorrect diagnosis.

Storage:When free iron levels are H, apoferritin is produced to

sequester iron & protect organs from toxic effect of excess free iron.

Iron is stored in intestinal mucosal cells & as ferritin, in macrophages in liver, spleen, & bone.

Elimination:No mechanism for excretionSmall amounts in feces & bile.

Anti anaemic DrugsAdverse effects:- Due to oral iron therapy;Nausea, epigastric discomfort, abdominal cramps, constipation, diarrhea, black stool.They may be minimized by lowering the daily dose or by taking iron tablets immediately after or with meals.

Anti anaemic DrugsParenteral iron therapy:1. It should be reserved for patients with documented iron

deficiency unable to tolerate or absorb iron ( patients With post gastrectomy, previous small bowel resection, malabsorption syndrome, inflammatory bowel D, noncompliance of patient, advanced chronic renal Disease .

2. Patients. With extensive chronic blood loss who can not be maintained with oral iron alone.

Anti anaemic DrugsIron dextran (ferric hydroxide + dextran), 50mg elemental

iron/mlRoute of administration: I/M, or by I/V infusion in 1-2

hours.Advantage of IV: eliminates local pain & tissue staining (SE:

IM). + allow delivery of entire iron dose.Also Iron sorbitol (IMMost adults needs about 1-2 G (20-40 ml) iron dextran for

iron deficiency anemia.

Anti anaemic DrugsAdverse effects:Local pain, tissue staining (brown discoloration of tissues overlying the inj. site), headache, fever, arthralgia, nausea, vomiting, bronchospasm, urticaria, anaphylaxis, and death.

Rare: anaphylactic & death.

Also dextran can cause hypersensitivity rxs.

Alternative preparations:

Iron-sucrose complex & iron Na+ gluconate complex. ONLY (IV) less hypersensitivity than dextran.

Anti anaemic DrugsChronic toxicity: known as hemochromatosis, when excess iron is deposited in heart, liver, pancreas and other organs cause organ failure and death.It occurs in patients with inherited hemochromatosis (excessive iron absorption), in patients who receive many red cell transfusions for long period

Anti anaemic Drugs2- coblamine a cobalt containing molecule is along with folic acid, a cofactor in the transfer of 1- carbon units, a step necessary for the synthesis of DNA.Impairment of DNA synthesis affects all cells, but because red blood cells must be produced continuously, deficiency of either coblamine or folic acid usually manifests first as anemia (megaloblastic anemia) Deficiency;; anemia, GI symptoms, & neurologic abnormalities.

Anti anaemic DrugsPharmacokinetics:

Source: Meat (liver), eggs, & dairy products.

coblamine is absorbed from the GIT in the presence of intrinsic

factor, a product of the parietal cells of the stomach.

Plasma transport is accomplished by binding to transcobalamin II.

Coblamine is stored in the liver in large amounts; a normal

individual has enough to last 5 years.

It is available in 2 forms

1. cyanocobalamine 2. hydroxy cobalamine has a longer circulating half life.

Anti anaemic DrugsClinical uses and toxicity:Both agents have equivalent effects.1. Treatment of naturally pernicious anemia2. anemia caused by gastric resectionBecause coblamine deficiency anemia is almost always caused by inadequate absorption, therapy should be by replacement of coblamine, using parenteral therapy.

No significant toxicity of coblamine occurred

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Uses:

1- Pernicious anemia

2- Neurologic abnormalities

3- Gastrectomy

4- Cyanide poisoning.

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• Initial therapy: 100-1000 mcg of vit B12 IM daily or every other day for 1-2 wks

• Maintenance: 100-1000 mcg IM once a month for life.

• .

Anti anaemic Drugs administration of folic acid to patients with coblamine

deficiency helps refill the tetrahydrofolate pool and partially or fully corrects anemia

However exogenous folic acid does not correct the neurologic defects of coblamine deficiency

[Note: Folic acid administration alone reverses the hematologic abnormality and, thus, masks the coblamine deficiency, which can then proceed to severe neurologic dysfunction and disease. Therefore, megaloblastic anemia should not be treated with folic acid alone.

Anti anaemic DrugsFolic acid: Like coblamine folic acid is required for normal DNA synthesis, and its deficiency usually presents as megaloblastic anemia.In addition deficiency of folic acid during pregnancy increase the risk of neural tube defects in the fetus

Anti anaemic DrugsPharmacokinetics:Source: yeast, liver, kidney, & green vegetables.Folic acid is readily absorbed from GIT. Only modest amount are stored in the body, so a decrease in dietary intake is followed by anemia within few monthsPharmacodynamics: Folic acid is converted to tetrahydrofolate by the action of dihydrofolate reductase

Anti anaemic DrugsOne important set of reactions involving tetrahydrofolate

and dihydrofolate constitutes the dTMP cycle, which supplies the dTMP required for DNA synthesis.

Rapidly dividing cells are highly sensitive to folic acid deficiency.

For this reason, antifolate drugs are useful in the treatment of various infections and cancers

Anti anaemic DrugsClinical use and toxicity:Folic acid deficiency is most often caused by dietary insufficiency and malabsorption.Anemia resulting from folic acid deficiency is readily treated by oral folic acid.Maternal folic acid deficiency is associated with increased risk of neural tube defects in the fetus, folic acid supplementation is recommended prior to and during pregnancy

Anti anaemic DrugsFolic acid supplements will correct the anemia but not the

neurologic deficits of coblamine deficiency.Folic acid has no recognized toxicity

Anti anaemic DrugsErythropoietin:ERYTHROPOIETN is produced by the kidneyReduction in its synthesis is responsible for anemia of renal failureActivation of receptors on erythroid progenitors in the bone marrow, it stimulates the production of red cells and increases their release from Bone Marrow.

Anti anaemic DrugsErythropoietin is used for anemia associated with renal

failure and some time effective for patients with other forms of anemia e.g. primary bone marrow disorder or anemia secondary to cancer chemotherapy or HIV treatment, bone marrow transplantation, AIDS or cancer

Toxicity: thrombosis ,cardiovascular events when used along with some other erythropoietic agents

Darbepoetin [dar-be-POE-e-tin] is a long-acting version of erythropoietin

Therefore, darbepoetin has decreased clearance and has a half life about three times that of erythropoietin.

Supplementation with iron may be required to assure an adequate response.

The protein is usually administered intravenously in renal dialysis patients, but the subcutaneous route is preferred.

When erythropoietin is used to target hemoglobin concentration 11.5g/dl, serious and life-threatening cardiovascular events, increased risk of death, shortened time to tumor progression and/or decreased survival have been observed.

The recommendations for all patients receiving erythropoietin include a minimum effective dose that does not exceed a hemoglobin level of 11.5 g/dl and this should not rise more than 1 g/dL over a 2-week period.

Agents Used to Treat Sickle-Cell Disease Clinical trials have shown that hydroxyurea can relieve the painful

clinical course of sickle-cell disease.In sickle-cell disease, the drug apparently increases fetal hemoglobin

levels, thus diluting the abnormal hemoglobin S (HbS). This process takes several months. Polymerization of HbS is delayed in the treated patients so that

painful crises are not caused by sickled cells blocking capillaries and causing tissue anoxia.

Important side effects of hydroxyurea include bone marrow suppression and cutaneous vasculitis.

It is important that hydroxyurea is administered under the supervision of a physician experienced in the treatment of sickle-cell disease.

A 22-year-old woman who experienced pain and swelling in her right leg presented at the emergency room. An ultrasound study showed thrombosis in the popliteal vein. The patient, who was in her second trimester of pregnancy, was treated for 7 days with intravenous unfractionated heparin. The pain resolved during the course of therapy, and the patient was discharged on Day 8. Which one of the following drugs would be most appropriate out-patient follow-up therapy for this patient, who lives 100 miles from the nearest hospital?

A. Warfarin.B. Aspirin.C. Alteplase.D. Unfractionated heparin.E. Low-molecular-weight heparin (LMWH).

A 60-year-old man is diagnosed with deep-vein thrombosis. The patient was treated with a bolus of heparin, and a heparin drip was started. One hour later, he was bleeding profusely from the intravenous site.The heparin therapy was suspended, but the bleeding continued. Protamine was administered intravenously, and the bleeding resolved. The protamine:

A. Degraded the heparin.B. Inactivates antithrombin.C. Activates the coagulation cascade.D. Activates tissue-plasminogen activator.E. Ionically combines with heparin.