Metabolic Block - MasterClass 2 Flashcards
Iron deficiency anaemia
Oral iron e.g ferrous sulfate
Side effects: Constipation Diarrhoea Epigastrjf pain Faecal impaction GI irritation Nausea
Interactions - mostly by reducing absorption: Levothyroxine Bisphosohonates Tetracyclines Ciprofloxacin Calcium and zinc salts
These medications should therefore be taken atleast 2 hours before oral iron
Dose of iron :
In presence of iron deficiency - Daily oral dose equivalent to 100-200mg of elemental iron produces maximum rate of rise of Hb (200mg ferrous sulfate contains 65mg iron)
Ferrous sulfate 200mg orally 3 times daily - to produce good therapeutic dose ( 65x3=195)
Should be continued for 3 months after the ahh conc had been restored in order to replenish Tissue iron stores
Some oral iron preps contain vitamin C
Iron salts
Oral iron:
Ferrous sulfate
Ferrous fumarate
Ferrous gluconate
Type of salt doesn’t matter - choice based on incidence of side effects and cost
Parenteral iron: Iron dextran Iron sucrose Ferric carboxymaltose Iron isomaltoside 1000
Generally reserved for use when oral therapy is unsuccessful due to pt not tolerating iron , not take it reliably or continuing blood loss or in malabsorption
Absorption, distribution and elimination of oral iron
Absorbed in duodenum and upper jejunum
Haem (fe2+) :
Fish
Poultry
Meat
Non haem Iron in a vegetarian diet: Vegetables sources Fruits Cereal Bread - Fe3+ inefficiently absorbed (ferric state(
Distribution:
Oxidised to ferric state and transported to circulation by ferroprotein
Transported to bone marrow and iron stores bound to goliblin transferrin
Stored as ferritin , haemosiderrin
2/3rds of iron - circulating RBCs
Half remainder - macrophages, reticuloendothelial cells and hepatocytes
Elimination - aging Red cells broken down by reticuloendothelial system - most of iron recycled via macrophages for further erythropoesis
Iron loss from body is low and usually occurs through shedding of mucosal cells containing ferritin
Menorrhagia
Stop excess blood loss by endometrial ablation or hormonal therapy or in extreme circumstances a hysterectomy
Pregnancy
Take folic acid - synthetic form of folate that is found in supplements and added to fortified foods
Folic acid can reduce risk of neural tube defects by preventing nutritional deficiency and by overcoming disruptions in folate metabolism related to genetic variation in folate related genes
Whereas folate is a water soluble B vitamin (B9) occurs naturally in foods such as beef liver , leafy green vegetables , oranges and legumes
Folate
Absorbed in duodenum and jejunum
Folate required for DNA synthesis, cell replication, formation of red cells.
Dihydrofolate reductase methylated and reduces folate monoglutamate to 5-methyltetrahydrofolate during absorption
Coenzymes in synthesis of prymidines and outlines and hence of DNA
Side effects are rare but can be GI disturbances but rare
Low risk women - 400micrograms daily before conception and until week 12 of pregnancy
High risk women (previous child with NTD or on anticonvulsants )- 5mg daily before conception and upto week 12.
If got sickle cell disease - then continue 5mg throughout pregnancy.
Patient leaflets and patient.co.uk - direct patient for more info
Vitamin B12 deficiency
Presents with a macrocytic anaemia and a megaloblastic bone marrow . Tongue becomes smooth and lining of small bowel can lead to malabsorption. Damage to the posterior and lateral neuronal tracts in spinal cord can also occur leading to subacute combined degeneration of the cord (SCDC)which may not be fully reversible after correction of Deficiency.
Hence if treating a macrocytic anaemia where there is a suspected B12 deficiency - always give B12 before starting folic acid as there is a risk of SCDC
Give hydroxocobalamin parenterally IM for vitamin B12 deficiency causing macrocytic anaemia
Causes of vitamin B12 deficiency include:
Diet - strict vegetarians and vegans
Intestinal malabsorption - inability to absorb B12 in terminal ileum due to damage there due to things like Crohn’s , lymphoma etc
deficiency in intrinsic factor - pernicious anaemia (destruction of gastric parietal cells with achlorhydria and failure of intrinsic factor production) , total or subtotal gastrectomy
How to measure severity of BPH
International prostate severity score (IPSS)
0-7 - mildly symptomatic
9-18 - moderately symptomatic
20-35 - severely symptomatic
Also includes a bother score
Incomplete emptying, frequency, intermittency , urgency , weak strewn and straining
Treatment for BPH
1st line:
Alpha blocker - tamsulosin
Also available:
Alfuzosin
Doxazosin
Terazosin
Highly selective for a1- adrenoceptor which are found mainly in smooth muscle such as blood vessels or Urinary tract ( bladder neck and prostate) stimulation induces contraction and blockade induces relaxation
Alpha blockers therefore cause vasodilation and a fall in BP and reduced resistance to bladder outflow
Side effects: Postural hypotension Dizziness Syncope ESP after first dose - effects on vascular tone.
Others: Headache Erectile disorders Rhinitis Asthenia Oedema
Interactions:
Mostly by pharmacodynamic interaction causing hypotension:
Other hypotensive agents such as CCBs , beta blockers , ACR Is, ARBs etc
PDE 5 inhibitors such as slidenafil and vardenafil
Enlarged prostate and at high risk of progression
5-alpha reductase inhibitor ( dutasteride or finasteride)
Risk of progression of symptoms from BPH is higher in older men, men with a poorer urine flow , higher symptom scores , evidence of bladder decompensation, ( such as chronic urinary retention), larger prostates or higher PSA levels.
If moderate to severe voiding symptoms and prostatic enlargement
Consider a combo of an alpha blocker and a 5- alpha reductase inhibitor
5-alpha reductase inhibitors
5-alpha Catalyses conversion of testosterone to dihydrotestosterone in prostate, hair follicles and other androgen sensitive tissues - these drugs inhibit this
Reduce size of prostate (more effective in men with larger prostates)
Long term reduction in prostate volume and need for surgery
Treatment for 6 to 12 months is needed
For those who cannot tolerate alpha blockers or who have predominantly irritant symptoms of concomitant erectile dysfunction
Side effects and interactions of 5- alpha reductase inhibitors
S.E :
Decreased libido
Ejaculatory or erectile dysfunction
Major SEs
Others:
Breast enlargement
Breast tenderness
Impotence
Interactions:
Verapamil and dilitiazem incr conc of dutasteride (yellow)
