Glucose 6 Phosphate Dehydrogenase (G6pd) Deficiency: What you need to know

Mr. Pharmacist, I have been told that I have G6PD deficiency. I have been warned about a number of medications to avoid. Kindly shed light on this condition especially with regards to the medications I need to stay away from. Glucose 6 Phosphate Dehydrogenase deficiency is a genetic disorder found mostly in people of African, Asian, Middle Eastern and Mediterranean decent.

The disorder can cause hemolytic anaemic (breakdown of the red blood cells) under certain conditions. Some years ago it used to be referred to as Familial Congenital Nonspheroytic Haemolytic Anaemia Glucose 6 Phosphate Dehydrogenase deficiency.

Well, this is a mouthful. The genetic disorder is an anomaly of the gene on the X         chromosome that controls the production of G6PD in cells. The defect is sex-linked, and transmitted from mother (usually a healthy carrier) to son (or daughter) who would be a healthy carrier too. In females only one of the two X chromosomes in each cell is active: consequently female heterozygous for G6PD deficiency have two populations of red blood cells deficient cells and normal cells.

The G6PD enzyme’s main role is to help cells convert carbohydrates into a form they can use. The conversion process leads to the production of another enzyme called reduced glutathione which is a very powerful antioxidant. Persons with G6PD deficiency do not have enough G6PD and do not produce enough reduced glutathione to protect cells from oxidative stress.

In all other cells (apart from red blood cells) this is not critical because of other means of protection for these cells. This is not the case for red blood cells (rbc) (which lacks a mitochondria) and could therefore be fatal. When RBCs are exposed to oxidative stress the cell membrane either bursts or is damaged because there is no, or not enough reduced glutathione to protect these cells. So without oxidative stress there will be no crisis. Yes. But it is difficult to prevent this in real life at all times. The first causes of oxidative stress are infections. Examples are viral hepatitis, influenza and some bacterial infections such as one by Salmonella. You will find a number of persons with G6PD deficiency who develop acute haemolysis as a result of infections.

The next group is medication. Several medicines are noted as posing definite risk for haemolysis.

There are common ones you will come across. It is therefore important to use medicines safely.

It is noted that up to about 20 per cent of Africans have G6PD defect. Someone shared his experiences with me after taking Ciprofloxacin for urinary tract infection. After about 48-72 hours he noticed a sudden rise in body temperature, yellow colouration of the skin and eyes. He became weak and really sick. He had to be rushed to the medical facility for prompt intervention.

Medications noted as definite risk for haemolysis include Quinolones (Ciprofloxacin, Levofloxacin), Sulfonamides (Co–?trimoxazole), Nitrofurantoin, Antimalarials (Mepacrine,

Pamaquine), Antimycobacterials (Dapsone, Para amino salicylic acid), Sulfones), Antineoplastics (Doxorubicin), Anthelmintics (Beta–?Naphthol, Niridazole). There are some noted as constituting a possible risk of haemolysis. These include Analgesics (Acetyl Salicylic acid, Dipyrone, Phenylbutazone), Sulphonylureas (Glibenclamide, Glimepiride, Gliclazide), Antimalarials (Quninine, Quinidine), Vitamin K substances (Menadione, Menadiol Sodium Phosphate). It is possible to graduate from a definite risk of haemolysis to a definite risk of haemolysis if you are on these medications and get knocked down by any an infection.

There are chemicals or substances that should be regarded as very harmful to persons with G6PD deficiency.

These include Naphthalene (moth balls), blue food colour and menthol (artificial mint flavor).

There are foods that are also harmful to persons with G6PD deficiency because of their tendencies to cause oxidative stress. A typical example is legume especially favs beans. Consumption of this legume can be fatal for persons with G6PD deficiency. Others (beans) are known to cause low level haemolysis. The red blood cells die but not in numbers to cause a person to seek immediate medical attention. It should be noted that low level haemolysis over time can cause other problems such as memory dysfunction, overworked spleen, liver, kidney and heart.

It can also cause iron overload. It is therefore advisable for persons with G6PD deficiency to stay away from such foods. I need to add that there are 400 genetic variants of the deficiency. One can determine his/her G6PD status by a simple blood test. Determination of the variant requires testing at a specialised genetic laboratory. Always remember that medicines are useful but inappropriate use of medicines could be harmful.

The writer is Chief

Pharmacist, Cocoa Clinic.

By Edward O. Amporful

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