Introduction:

Darbepoetin is a bone marrow stimulating medication in injection form which is synthetic in preparation by recombinant DNA technology. It is an artificially prepared protein that acts as a precursor for RBC production. It is used in patients who have developed problems that lead to reduced red blood cell production.

Darbepoetin has a serum half life three times more as compared to epoetin alfa. It contains a chain of five amino acids and has two carbohydrates linked to the chain. It is similar to erythropoietin.

It has a wide range of indications and at the same time, one has to take into account its contraindication and side effects as mentioned below.

How does darbepoetin increase RBC production?

• RBCs are produced in bone marrow in human beings. 
• The kidney is the organ that produces erythropoietin. Erythropoietin is the substance that stimulates the bone marrow to produce RBCs. Erythropoietin binds to the erythropoietin receptors in the bone marrow which further produces the required protein and RBC production starts.
• The process of premature RBC to reticulocyte and mature RBC formation is termed as erythropoiesis. And for this process to occur, erythropoietin is the precursor.
• When erythropoietin production in the kidney is insufficient or abnormal, there is no precursor to stimulate the bone marrow to produce RBCs.
• In such patients, synthetic injection of erythropoietin in the form of darbepoetin is administered.
• Darbepoetin, just like natural erythropoietin, goes and binds to the erythropoietin receptors in the bone marrow.
• Once the binding takes place the production of RBC or erythropoiesis starts.

Where is darbepoetin used?

• Chronic Kidney disease: in patients who have had kidney disease for a long time have all the kidney functions reduced in general. It also includes its function of producing erythropoietin. Reduced erythropoietin means reduced red blood cells. Hence to prevent anaemia, blood abnormalities, etc. Darbepoetin injections are used. 
• Cancer and chemotherapy: cancer is a condition where there is uncontrolled, abnormal, and quick multiplication of cells. Hence, this condition has a lot of contribution to causing anaemia. More than the condition itself, its treatment measures like chemotherapy causes severe anaemia in patients. To treat anaemia this medication is used. The dose is kept low just to reduce the anaemia as it may cause other complications in these patients.
• Anaemia: it is a condition where haemoglobin is less than the normal levels as of the age and gender of the person. Haemoglobin is present in RBC and oxygen is carried by haemoglobin which is in turn packed inside the RBC. So, when RBCs are increased in number, haemoglobin increases proportionately reducing anaemia. 

Dosage of darbepoetin.

• Chronic Kidney disease patient 0.45mcg/kg for 4 weeks. The dose changes with respect to the disease, age, and gender. It also depends on the severity of the illness.

How do I use darbepoetin?

• Do not shake the container which has the medicine darbepoetin.
• Clean the skin surface before injecting.
• Do not use the medication in which clumps, clots, or suspensions are seen.
• Use a new, unused needle each time.
• Do not use the medication if the colour changes are noted in the container.
• Prepare an injection once everything else is ready and you are about to take it.
• Proper training and techniques for self-injection should be taken prior.
• This medication is available only when a medical professional prescribes it to you. It is illegal to use this medication without a prescription.

How is darbepoetin misused?

• It is a medication that is used by athletes illegally.
• Doping has been reported for this medication.
• As darbepoetin increases RBC count it, in turn, increases haemoglobin and thus oxygenation.
• The aerobic capacity of the body increases and thus is misused.
• Thus this medication is not available without a prescription.
• It is illegal to ask for this medication without any medical need.

What are the drugs that interact with darbepoetin?

• Captopril, enalapril, ramipril.
• Cyclosporine
• Thalidomide
• Lenalidomide.
• It also interacts with diseases like hypertension, thrombo-embolism, dialysis, epilepsy, or seizures.
• Interaction is also seen with alcohol consumption. It leads to severe or hypertensive crises.

What route of administration is used for darbepoetin?

• It is administered intravenously.
• It is also administered subcutaneously.
• Only injection preparations are used.

What are the contraindications for darbepoetin?

• The patient who has uncontrolled hypertension.
• The patient who is sensitive to any content of this medication.
• The patient who has dermatitis, lymphadenopathy, and infections.
• The patient who has a strong history of thromboembolism, and cardiac complications.

What are the adverse effects of darbepoetin?

• Cardiovascular effects: cardiac arrest, cardiac failure, arrhythmias, embolism, thrombosis, hypertensive crisis.
• Respiratory effects: breathlessness, cough, lung congestion, chest discomfort, upper respiratory tract infections, pharyngitis.
• Psychosomatic effects: anxiety, social withdrawal, depression, slow thought process.
• Dermatological effects: irritation at the injection site, rashes, pruritus, redness.
• Neurological effect: headache, dizziness, drowsiness, seizures.
• Gastrointestinal effects: nausea, vomiting, diarrhoea, appetite disorder, gastric irritation.
• Musculoskeletal effects: muscle pain, cramps, weakness, fatigue, and difficulty in moving.
• Mobility effects: difficulty in walking, difficulty in moving the upper limb.
• Join effects: arthralgia, stiffness, pain, weakness.

What should your doctor know before starting you on darbepoetin?

• Your history of previous cardiovascular health, hypertension, kidney disease, etc.
• Allergy, history of use of this medication previously.
• Your haemoglobin levels and blood culture reports.
• Fitness etc.

Where is darbepoetin available and what is its brand name?

• It is available in pharmaceutical retail centres.
• Hospital setup, dispensary.
• It is available by the name: Aranesp