- Didanosine, also known by its brand name Videx, is an antiretroviral medication used in the treatment of human immunodeficiency virus (HIV) infection. It belongs to a class of drugs called nucleoside reverse transcriptase inhibitors (NRTIs), which work by interfering with the reverse transcriptase enzyme—an essential component that HIV uses to replicate within human cells. By blocking this enzyme, didanosine helps to reduce the amount of HIV in the body and slows the progression of the disease, although it does not cure it.
- Didanosine is a synthetic analog of deoxyadenosine and was among the earliest antiretroviral agents developed after zidovudine (AZT). Once inside the body, it is converted to its active form, dideoxyadenosine triphosphate (ddATP), which competes with the natural substrate of reverse transcriptase and gets incorporated into viral DNA. This incorporation results in premature chain termination, effectively halting viral replication.
- The drug is available in both chewable tablets and extended-release capsules, and it must be taken on an empty stomach, as food significantly reduces its absorption. The dosage of didanosine depends on the patient’s weight, age, renal function, and whether it is being used in combination with other antiretroviral drugs. It is often used as part of highly active antiretroviral therapy (HAART), which involves a combination of multiple drugs to maximize effectiveness and prevent resistance.
- Despite its efficacy, didanosine is associated with several serious side effects, which have limited its use in recent years. The most significant adverse effects include pancreatitis, peripheral neuropathy, and lactic acidosis with hepatic steatosis. Other common side effects include nausea, diarrhea, rash, and abdominal pain. Long-term use may also be associated with retinal changes and optic neuritis. Due to these risks and the availability of safer, more effective alternatives, didanosine is less commonly used today, especially in high-income countries.
- In clinical practice, didanosine is generally reserved for specific cases where other treatment options are limited, such as in patients who cannot tolerate other NRTIs or in resource-limited settings. Its use requires careful monitoring, including regular assessments of liver and pancreatic function. Moreover, it should not be co-administered with certain drugs, such as tenofovir, due to an increased risk of toxicity.
