Didanosine

Key facts

• Didanosine (ddI) is a nucleoside reverse transcriptase inhibitor (NRTI) used together with other antiretroviral drugs to treat HIV infection. It is not used alone.
• It is taken on an empty stomach, at least 30 minutes before or 2 hours after food, because food reduces how much is absorbed.
• Didanosine can cause pancreatitis, which can be fatal, and lactic acidosis with an enlarged, fatty liver. Avoid alcohol entirely while taking it, since alcohol adds to both risks.
• Seek urgent care for severe abdominal pain, persistent vomiting, or unusual muscle pain with weakness and rapid breathing.

What didanosine treats

Didanosine treats HIV-1 infection as part of a combination antiretroviral regimen. It is now used less often than newer antiretrovirals because of its side-effect profile, but it is still prescribed when other options are not suitable. It does not cure HIV and does not treat other infections.

How didanosine works

Didanosine is a nucleoside analogue. Cells convert it into an active triphosphate form that HIV's reverse transcriptase enzyme mistakes for a natural building block of DNA. When the enzyme incorporates it into the growing viral DNA chain, that chain stops extending, so the virus cannot complete a working copy of its genetic material and cannot spread to new cells.

Before you take it

• Tell your prescriber about any history of pancreatitis, liver disease, peripheral neuropathy (nerve pain or numbness in the hands or feet), or heavy alcohol use, all of which raise the risk of serious side effects.
• Avoid alcohol completely while on didanosine.
• Combining didanosine with stavudine is avoided where possible, as together they substantially increase the risk of nerve damage and pancreatitis.
• If you are pregnant, tell your prescriber; the combination of didanosine and stavudine during pregnancy has been linked to fatal lactic acidosis and is avoided.

Side effects

Common effects are diarrhoea, headache, and tingling or numbness in the hands or feet.

Stop and seek urgent medical care for any of these:

• Severe or persistent abdominal pain, nausea, or vomiting, which can signal pancreatitis.
• Unusual tiredness, rapid or difficult breathing, or muscle pain, which can signal lactic acidosis.
• Yellowing of the skin or eyes, dark urine, or pale stools.
• New or worsening numbness, tingling, or burning pain in the feet or hands.

Safety essentials

• Pancreatitis and lactic acidosis are the defining risks of didanosine; avoiding alcohol and reporting severe abdominal pain, persistent vomiting, or unusual muscle weakness without delay is the single most important safety step.
• Your prescriber will check liver function and watch for signs of nerve damage during treatment.
• Take doses on an empty stomach exactly as directed, since the buffered formulation protects the drug from stomach acid and food reduces its absorption.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.