What a great day! A fresh start for a whole new discussion =D
Ok we are going to talk on Iron therapy
There are conditions in which we need different kind of iron therapy, those include:-
1) Iron Deficiency – Therapy concentrating in increasing body iron level
a) Iron tablets therapy
+ Ferrous fumarate
+ Ferrous sulfate
+ Ferrous gluconate
b) Parenteral iron therapy
+ Iron dextran
+ Ferric gluconate
+ Iron sucrose
2) Iron Overload – Therapy concentrating in reducing body iron level
a) Iron chelating therapy
+ Deferasirox – tablet
+ Deferoxamine – parenteral
Let us discuss on the therapy used for iron deficiency. Before that, let us list few factors lead to iron deficiency
1) Reduced intake such as:-
a) Strict vegetarians
b) Poor economic background having poor diet
2) Increased demand such as:-
a) Pregnancy increases iron demand almost fourfold
3) Increased loss such as:-
a) Traumatized patient
Therapeutic strategy of iron therapy
1) Iron absorption happens at the
a) Duodenum
b) Proximal part of jejunum
So, it is unwise to formulate iron tablet in enteric coated form since enteric coated tablet/capsule protects the drug from dissociating at the upper part of small intestine
2) Iron absorption will be impaired in the presence of certain foods such as:-
a) Phytin in wholegrains
b) Tannin in tea
So, iron tablet should not be given with food at all.
3) Iron absorption is sensitive towards pH changes; it is best absorb in reduced form (Fe2+)
a) High pH; less absorb since at higher pH iron tends to be oxidized into ferric (Fe3+)
+ Therefore, it should be taken 2 hours after consumption of antacids
b) Lower pH; greater absorption since at lower pH iron tends to be reduced into ferrous (Fe2+)
+ Therefore, it is wise to take iron tablet together with vitamin C (Ascorbic ACID)
We have few pharmaceutical route of administrations formulated for iron therapy which include oral route (tablet form) and parenteral route (IV and IM).
Let us discuss the oral route of administration.
Oral route is the SAFEST, CHEAPEST AND MOST WIDELY USE in iron deficiency therapy
1) Tablet forms (Faculty Sains Gunaan)
a) Ferrous fumarate (Faculty)
b) Ferrous sulfate (Sains)
c) Ferrous gluconate (Gunaan)
P/s:- The pneumonic of Faculty Sains Gunaan is following an order of amount of iron per tablet; fumarate having the highest iron content.
Let us discuss in detail for ferrous fumarate since ferrous fumarate is the most widely used iron tablet in the hospital setting. You can read more about other types – no pressure =)
Ferrous fumarate 300mg
Having 40% of iron content per tablet, means there is 120mg of ferrous in 300mg tablet of ferrous fumarate.
Reddish-orange in color due to the fumarate salt.
Pharmcokinetics
1) Absorption
a) Best absorb in low pH
b) Absorb at duodenum and proximal jejunum
2) Distribution
a) 90% of protein binding
Side effects (largely dose dependent, resolves upon withdrawal of therapy)
1) Abdominal discomfort
2) Nausea
3) Diarrhea
4) Constipation
5) Dark discoloration of stool (due to unabsorbed iron)
6) Metallic taste
Patient information
1) Tablet should be taken before meal or without food
2) Tablet should be taken 2 hours after consuming antacids
3) It is wise to take with vitamin C tablet together with iron tablet to increase absorption
4) Iron therapy will lead to dark discoloration of stool. It is not harmful.
Let us go to the next route of administration iron deficiency therapy; parenteral route. Parenteral iron deficiency therapy is less used because it is EXPENSIVE, LOT OF SIDE EFFECTS and TEDIOUS TO ADMINISTER. Therefore, only under certain condition parenteral route is advisable, such as:
1) Patient who can’t tolerate oral form – comatose patient
2) Iron loss exceeds oral iron replacement
3) Inflamed bowel
4) Dialysis patient
5) Anemic cancer patient
Types of preparation
Iron dextran (most widely used)
Route of admin – IV or IM
Formulation
1) INFeD( 100mg/2ml – low molecular weight
2) Dexferrum( 100mg/2ml – high molecular weight
Side effects (prominently seen in high molecular weight formulation; Dexferrum( 100mg/2ml)
1) Local effects
a) Localized pain
b) Phlebitis
c) Muscle necrosis
2) Systemic effects
a) Anaphylaxis shock – 1% of patient
b) Fever
c) Urticaria – elevated patches on the skin, either red or pale in color
Other parenteral preparation
1) Iron gluconate 62.5mg/5ml ampoule
2) Iron sucrose USP ampoule
These formulations have less side effects and allergic reactions.
Now let us go to the next iron therapy; iron chelating therapy.
This therapy concentrates in condition of iron overload or iron toxicity.
Iron can easily accumulate in the body since there is no physiological route in which the iron can be excreted out of the body.
Accumulation of iron which leads to tissue damage is called hemochromatosis. Hemochromatosis can been due to:-
1) Inherited hemochromatosis
2) Regular blood transfusion in major thalassemic patient
Iron overload can damage the tissue due to:-
1) Its ability to convert hydrogen peroxide into free radicals
2) Free radicals in return may attack:-
a) Cellular membrane
b) DNA
c) Proteins
Hemochromatosis can lead to
1) Liver cirrhosis
2) Cardiomyopathy
3) Cardiac failure
4) Pancreatic failure
Like iron deficiency treatment, iron overload therapy also consist of 2 types of route of administration; parenteral and oral.
Parenteral (most commonly used)
Deferoxamine (Desferal(500mg/vial)
Mechanism of action
1) Remarkable affinity towards ferric (Fe3+) iron.
2) Removes iron from
a) Ferritin
b) Hemosiderin
c) Transferrin (to a lesser extent)
3) BUT IT DOES NOT REMOVE IRON FROM (beneficial property)
a) HEMOGLOBIN
b) CYTOCHROME
Side effects
1) Hypotension
2) Allergic reaction
3) Abdominal discomfort
4) Diarrhea
Contraindicated
1) Renal imsufficiency
2) Pregnancy
Oral iron chelator
Deferasirox 125mg Tablet
Beneficial for major thalassemic patient who:-
1) Refused to take deferoxamine
2) Pregnant
What a long discussion we had. I hope it might bring some helps for all of you. Thanks for reading my blog! =)
Virtual Medic 