Updated: Sep 4, 2020
This month I have the pleasure of introducing you to ferrous sulphate: it's riveting!
Ferrous sulphate belongs to a group of medicines known as "oral iron"
Mechanism of Action
Ferrous sulphate is composed of ferrous iron and it's sulphate salt.
Once ingested, and whilst winding its way through the gastrointestinal tract, a proportion of the ferrous sulphate will cleave into its component parts (i.e. the ferrous iron part and the sulphate part). The former (the bit that floats along as ferrous iron) will be absorbed into the body.
Now, to reach the blood stream the ferrous iron has to pass into the wall of the gastrointestinal tract, be converted into ferritin (more on that in a second) and then be transported out the other side and into the circulation.
So, what’s ferritin?
I’m glad you asked. Well, because free iron is reactive and toxic to the body, it becomes attached to a protein to prevent it from causing mischief – the resulting combination of iron and protein is called ferritin. Ferritin is the way in which iron is stored, therefore it is found in the blood stream and also within tissue “storage sites”, such as the liver.
Another protein worth mentioning is one known as transferrin. This character patrols the circulation and rapidly sweeps up any free iron. Once it has collected 2 iron ions (which is it’s maximum load) it drops them off at one of the body's storage sites for safe keeping, as ferritin. It also acts as a porter, so when iron is needed by a site such as bone marrow, transferrin takes some out of the ferritin storage and delivers it.
Why does bone marrow need iron?
As you may know, iron is contained within a large protein known as haemoglobin. Haemoglobin is produced in the liver and bone marrow. The role of haemoglobin is to bind onto blood gases – predominantly oxygen – and transport it around the body in order to fuel our muscles and tissues. It does this via the blood – specifically red blood cells known as erythrocytes – which contain approximately 270 million haemoglobin each! So there you have it – iron is the central component of haemoglobin, the body’s oxygen transporter.
In terms of mechanism of action however, ferrous sulphate has no intrinsic therapeutic activity – meaning that once it is absorbed it has no independent chemical effect and acts the same as dietary iron. Simply put, it is a “supplement”.
A deficit of iron results in a condition known as iron deficiency anaemia, or IDA. As we’ve discussed, iron contained within haemoglobin is vital to our oxygen transport system. A lack of haemoglobin causes tiredness, an inability to concentrate, weakness, inability to regulate temperature and a general lack of energy. A bit like how you feel after sitting in a stuffy and poorly ventilated office or classroom for the day!
Iron supplementation aims to correct this deficit; first by elevating the individual’s levels of haemoglobin, and secondly by restoring the stores of ferritin within the body. The latter takes about 3 months, once the patient has achieved a normal haemoglobin level.
Did you know, there’s enough iron in a healthy human to make a whole nail?
Thanks for reading. Have a marvellous weekend, wherever you are!