Drugs - Haematology Flashcards
Give 2 types of iron used in the treatment of iron deficiency anaemia?
Ferrous sulphate
Ferrous fumarate
2 main functions of iron in RBCs?
- Essential for erythropoiesis (formation of new RBCs)
- Required for the synthesis of the haem component of Hb which gives RBCs the ability to carry O2
In what form is iron best absorbed?
In its ferrous state (Fe2+)
Where is iron absorbed?
in the duodenum and jejunum
Once absorbed into the bloodstream, what is iron bound by?
Transferrin
Function of transferrin?
Transferrin transports iron either to be used in the bone marrow for erythropoiesis or to be stored as ferritin in the liver, reticuloendothelial system, bone marrow, spleen and skeletal muscle
How is iron stored?
As ferritin
where does erythropoiesis occur?
Bone marrow
Function of kidneys in erythropoiesis?
Produce erythropoietin (EPO), a hormone that signals your bone marrow to make red blood cells.
Side effects of iron therapy?
- GI upset – nausea, epigastric pain, constipation & diarrhoea
- Patients may notice their bowel motions turn black on treatment
- IV iron can cause injection site irritation and hypersensitivity reactions (e.g. anaphylaxis)
How can iron therapy affect stools?
Patients may notice their bowel motions turn black on treatment
Contraindications for oral iron?
- Oral iron therapy may exacerbate bowel symptoms in those with intestinal disease – e.g. IBD, diverticular disease, intestinal strictures
- Unsafe swallow
Contraindications for IV iron?
IV iron should be used with caution in those with an atopic predisposition due to risk of anaphylaxis
Interactions of oral iron salts?
Oral iron salts can reduce the absorption of other drugs e.g. levothyroxine and bisphosphonates
Why should iron therapy be stopped 7 days prior to a colonoscopy?
People with iron deficiency often require colonoscopy to investigate the cause of their anaemia. However, oral iron can turn stools black and sticky. This is problematic for visualizing the bowel during lower GI endoscopy as the sticky black stool coats the colon ad obscures the view
What is hydroxocobalamin?
This is a synthetic form of cobalamin/vitamin B12
What is thiamine?
Vitamin B1
What is phytomenadione?
plant form of vitamin K
What is thiamine used in the treatment/prevention of?
Used in the treatment and prevention of Wernicke’s encephalopathy and Korsakoff’s psychosis which are manifestations of severe thiamine deficiency
What vitamin is folate?
B9
What is folic acid?
synthetic form of folate/vitamin B9
2 major indications for folic acid?
- Used in megaloblastic anaemia as a result of folate deficiency
- Used in the first trimester of pregnancy to reduce the risk of neural tube defects
2 major indications for hydroxocobalamin?
Treatment of megaloblastic anaemia and subacute combined degeneration of the cord as a result of B12 deficiency
2 major indications for phytomenadione?
- Recommended for all newborn babies to prevent vitamin K deficiency bleeding
- Used to reverse the anticoagulant effects of warfarin (prothrombin complex concentrate should also be given in cases of major bleeding)
What type of blood product should be used in warfarin reversal?
prothrombin complex concentrate (PCC)
How does phytomenadione reverse warfarin?
Phytomenadione reverses warfarin by providing a fresh supply of vitamin K for the synthesis of vitamin K dependent clotting factors by the liver
When should folic acid be given in pregnancy?
1st trimester AND preconception period
In patients with co-existing B12 and folate deficiency, why should you replace both vitamins simultaneously?
Replacing folate alone may be associated with the progression of neurological manifestations of vitamin B12 deficiency (major concern is risk of provoking subacute combined degeneration of the cord)
Why is phytomenadione less effective in reversing warfarin in those with severe liver disease?
as clotting factors are synthesised in the liver
How is hydroxocobalamin administered?
IM injection
2 main indications for folinic acid?
- Used to decrease the toxic effects of methotrexate and pyrimethamine
- Can be used to treat folate deficiency that results in anaemia