Didanosine slows the progress of HIV infection. It is one of a number of medicines that you will need to take regularly.
Didanosine should be taken when your stomach is empty, as the presence of food in your stomach prevents the medicine from being absorbed properly. Follow carefully the instructions your doctor gives to you about when you should take the tablets or capsules.Didanosine has been associated with some serious side-effects. Your doctor will discuss these with you before you start treatment.
|Type of medicine||A nucleoside reverse transcriptase inhibitor antiretroviral medicine|
|Used for||Human immunodeficiency virus (HIV) infection, in adults and children|
|Available as||Tablets and capsules|
Didanosine is an antiretroviral medicine. It is used for human immunodeficiency virus (HIV) infection. It slows the progress of HIV infection, but it is not a cure. HIV destroys cells in the body, called CD4 T cells. These cells are a type of white blood cell and are important because they are involved in protecting your body from infection. If left untreated, the HIV infection weakens your immune system so that your body cannot defend itself against bacteria, viruses and other germs. Didanosine slows down the progress of HIV infection by reducing the amount of virus in your body. It does this by stopping the virus from copying (replicating) itself.
Didanosine will be prescribed for you by a doctor who is a specialist. It belongs to a group of antiretroviral medicines known as nucleoside reverse transcriptase inhibitors (NRTIs). It is given alongside a number of other antiretroviral medicines, as part of a combination therapy. Taking three or more antiretroviral medicines at the same time is more effective than taking one alone. Taking a combination of different medicines also reduces the risk that the virus will become resistant to any individual medicine. It is vital to take your antiretroviral medicines exactly as prescribed to maintain success and to help to prevent the virus from becoming resistant to the medicines. These medicines are usually taken for life.
Before taking didanosine
Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking didanosine it is important that your doctor knows:
- If you are pregnant, trying for a baby or breast-feeding.
- If you have any problems with the way your liver works, or if you have problems with the way your kidneys work.
- If you drink a lot of alcohol.
- If you have ever had inflammation of your pancreas, called pancreatitis.
- If you feel any tingling or pain in your arms or legs, or if you have any numbness in these areas.
- If you are taking any other medicines. This includes any medicines which are available to buy without a prescription, as well as herbal and complementary medicines.
- If you have ever had an allergic reaction to a medicine.
How to take didanosine
- Before you start the treatment, read the manufacturer's printed information leaflet from inside your pack. It will give you more information about didanosine, and it will also provide you with a full list of the side-effects which you could experience from taking it.
- Take didanosine exactly as your doctor tells you to. You will be asked to take one or two doses each day. If you are taking two doses a day, take them 12 hours apart, so in the morning and the evening. You will be given either capsules or tablets - your doctor will tell you how many tablets/capsules you should take for each dose:
- If you have been given capsules to take, swallow the capsule whole with a large glassful of water. Do not open up the capsules, as this may reduce how much of the medicine your body absorbs.
- If you (or your child) have been given tablets, the tablets must either be chewed well before they are swallowed, or alternatively, you can crush the tablets and stir them into 30 ml of water. If needed, you can add 30 ml of apple juice to the tablet and water mixture to improve the taste.
- If your child has been prescribed didanosine tablets and is taking only one tablet as a dose (this applies to children under 1 year of age), you can crush the tablet and stir it into 15 ml of water. If needed, you can add a further 15 ml of apple juice to the tablet and water mixture to improve the taste.
- Try to take didanosine at the same times each day, as this will help you to remember to take it regularly. You should take your doses 'on an empty stomach'. If you are taking capsules, this means that you should take them two hours before a meal, or you should wait until two hours after you have eaten. If you are taking tablets, it means you should take them at least 30 minutes before a meal. This is because your body absorbs less didanosine when there is also food in your stomach, which means that the medicine is less effective.
- If you forget to take a dose, take it as soon as you remember (keeping in mind that it should be taken without food). If it is time to take your next dose when you remember, leave out the missed dose and just take the dose that is due. Do not take two doses together to make up for a forgotten dose.
Getting the most from your treatment
- Keep your regular appointments with your doctor so that your progress can be monitored. You will need to have regular blood tests to check how well your medicines are working.
- It is important that you continue to take didanosine and your other antiretroviral treatment regularly. This will help to prevent the HIV from becoming resistant to the medicines you are taking. Even if you miss only a small number of doses, the virus can become resistant to treatment.
- If you develop an infection soon after you start the treatment, let your doctor know. As a result of taking didanosine, your immune system may start fighting an infection which was present before you started the treatment, but which you may not have been aware of.
- Follow carefully any advice your doctor gives to you about making lifestyle changes to reduce any risk of damage to your heart and blood vessels. These can include stopping smoking, eating healthily and taking regular exercise.
- Didanosine has been associated with serious side-effects in some people who have taken it. These include inflammation of the pancreas (pancreatitis), and a problem where there is too much lactic acid in the blood, known as lactic acidosis. The symptoms associated with these side-effects are listed in the next section 'Can didanosine cause problems?'. If you develop any of the symptoms listed below, you must let your doctor know straightaway, as they can worsen, and may even become life-threatening.
- Some people taking antiretroviral medicines develop changes to the way body fat is distributed in the body. This can result in changes to body image. Your doctor will discuss the possibility of this with you.
- Although treatment with antiretroviral medicines may reduce the risk of you passing HIV to others through sexual contact, it does not stop it. It is important that you use condoms.
- It is not uncommon for people with HIV to feel low or even depressed, especially soon after the diagnosis has been made and treatment has been started. If you have any feelings of depression, or any distressing thoughts about harming yourself then you should speak with your doctor straightaway.
- Your doctor is likely to recommend that your eyesight be checked every year. If you notice any problems with your eyesight in between these checks, you should let your doctor know about this.
- Some people who have taken antiretroviral medicines (particularly over a long time) have developed a condition called osteonecrosis. This is a bone disease where bone tissue dies because there is a reduced blood supply to it. It leads to joint pains and stiffness, and can cause difficulties in movement. If you notice any of these symptoms, speak with your doctor.
- If you buy any medicines, supplements or herbal remedies 'over the counter', check with a pharmacist that they are suitable to take with didanosine and your other medicines. This is because some medicines interfere with antiretrovirals and can stop them from working properly.
- If you are having an operation or dental treatment, tell the person carrying out the treatment which medicines you are taking.
- Treatment for HIV is usually lifelong. Continue to take didanosine regularly, even if you feel well. This is to keep your immune system healthy.
Can didanosine cause problems?
Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with didanosine. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.
|Very common didanosine side-effect (affects more than 1 in 10 people)||What can I do if I experience this?|
|Diarrhoea||Drink plenty of water|
|Common didanosine side-effects (these affect less than 1 in 10 people)||What can I do if I experience this?|
|Feeling or being sick, tummy (abdominal) pain, wind||Stick to simple meals - avoid fatty or spicy food. If it continues, speak with your doctor|
|Headache, muscle aches and pains, chills or high temperature (fever)||Ask your doctor or pharmacist to recommend a suitable remedy|
|Tingling in the feet or hands, or feelings of numbness||Speak with your doctor about this|
|Feeling tired or weak||Do not drive and do not use tools or machines while affected|
|Rash, breast enlargement in men, loss of weight, dry mouth||If troublesome, speak with your doctor|
|Liver problems and changes to some blood tests||Your doctor will monitor for these|
Your doctor will discuss with you the possibility of less common but more serious side-effects occurring, such as inflammation of the pancreas (pancreatitis) or lactic acidosis. Let your doctor know straightaway if you develop any of the following symptoms.
- The most common signs of pancreatitis are abdominal pain, feeling or being sick, fever, and feeling generally unwell.
- The most common signs of lactic acidosis are feeling or being sick, tummy pain, loss of appetite, loss of weight, feeling weak or dizzy, and fast or gasping breathing.
If you experience any other symptoms which you think may be due to the medicine, speak with your doctor or pharmacist for further advice.
How to store didanosine
- Keep all medicines out of the reach and sight of children.
- Store in a cool, dry place, away from direct heat and light.
Important information about all medicines
Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital at once. Take the container with you, even if it is empty.
This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
If you have any questions about this medicine ask your pharmacist.
Further reading & references
- Manufacturer's PIL, Videx® EC 125 mg, 200 mg, 250 mg and 400 mg Gastro-resistant Capsules; Bristol-Myers Squibb Pharmaceutical Limited, The electronic Medicines Compendium. Dated April 2016.
- Manufacturer's PIL, Videx® 25 mg Chewable or Dispersible Tablet; Bristol-Myers Squibb Pharmaceutical Limited, The electronic Medicines Compendium. Dated April 2016.
- British National Formulary; 71st Edition (Mar-Sep 2016) British Medical Association and Royal Pharmaceutical Society of Great Britain, London
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr John Cox