Stavudine

Key takeaways

Stavudine belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Stavudine to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Stavudine from memory before moving on to harder problems.

Reference excerpt

Stavudine (d4T), sold under the brand name Zerit among others, is an antiretroviral medication used to prevent and treat HIV/AIDS. It is generally recommended for use with other antiretrovirals. It may be used for prevention after a needlestick injury or other potential exposure. However, it is not a first-line treatment. It is given by mouth. Common side effects include headache, diarrhea, vomiting, rash, and peripheral nerve problems. Severe side effects include high blood lactate, pancreatitis, liver toxicity, and an enlarged liver. It is not generally recommended in pregnancy. Stavudine is in the nucleoside analog reverse-transcriptase inhibitor (NRTI) class of medication. Stavudine was first described in 1966 and approved for use in the United States in 1994. It is available as a generic medication.

Medical uses Stavudine is used in the treatment of HIV-1 infection, but is not a cure. It is not normally recommended as initial treatment. Stavudine can also reduce the risk of developing HIV-1 infection after coming into contact with the virus either at work (e.g., needlestick) or through exposure to infected blood or other bodily fluids. It is always used in combination with other HIV medications for the better control of the infection and a reduction in HIV complications. The World Health Organization (WHO) recommended stavudine to be phased out due to its high toxicity levels. If the drug must be used, it is recommended to use low dosages to reduce the occurrence of side effects; however, a 2015 Cochrane review found no clear advantage between high and low dosage regimens.

Pregnancy and breastfeeding Stavudine has been demonstrated to affect the fetus in animal studies but no data are available from human studies. Pregnant women should therefore be given stavudine only if the potential benefits outweigh the potential harm to the fetus. Additionally, there have been case reports of fatal lactic acidosis in pregnant women receiving combination therapy of stavudine and didanosine with other antiviral agents. The Centers for Disease Control and Prevention recommend that HIV-infected mothers not breastfeed their infants, in order to avoid the risk of HIV transmission through breast milk. There is also evidence that stavudine gets into animal breast milk, although no data are available for human breast milk.

Children Stavudine is safe for use in children infected with HIV from birth through adolescence. Adverse effects and safety profile are the same as adults.

Elderly There is no data available for stavudine use in HIV-infected adults aged 65 years or older. However, among 12,000 people over the age of 65, 30% developed peripheral neuropathy. Additionally, since the elderly are more likely to have decreased renal function, they are more likely to develop toxic side effects.

Adverse effects Common side effects

Nausea Vomiting Diarrhea Headache Upset stomach Severe side effects

Peripheral neuropathy Lactic acidosis Pancreatitis Hepatotoxicity Hepatomegaly with steatosis Lipoatrophy/lipodystrophy (fat redistribution/accumulation) Individuals are monitored for the development of these serious adverse effects. The development of peripheral neuropathy is shown to be dose related, and may be resolved if the drug is discontinued. Individuals with advanced HIV-1 disease, a history of peripheral neuropathy, or individuals on other drugs that have association with neuropathy develop this side effect more often. Stavudine has been shown in laboratory test to be genotoxic, but with clinical doses its carcinogenic effects are non-existent. Hyperlactatemia, bone mineral density (BMD) loss, reduction in limb fat and an increase in triglycerides were found when administered in high dosages. It is also one of the most likely antiviral drugs to cause lipodystrophy, and for this reason it is no longer considered an appropriate treatment for most patients in developed countries. According to a study in Thailand, HLA-B*4001 may be used as a genetic marker to predict which patients will develop stavudine-associated lipodystrophy, to avoid or shorten the duration of stavudine. It is still used as a first choice in first line therapy in resource poor settings such as in India. Only in the case of development of peripheral neuropathy or pregnancy is treatment changed to the next choice, zidovudine. The safety and effectiveness of dosage titration was not reported in treatment naive patients. It was only reported in those patients with sustained virologic suppression. These findings are not generalized to stavudine used in ART naive patients who have high viral loads. In November 2009, the World Health Organization (WHO) stated that "[The WHO] recommends that countries phase out the use of stavudine, or d4T, because of its long-term, irreversible side-effects. Stavudine is still widely used in first-line therapy in developing countries due to its low cost and widespread availability. Zidovudine (AZT) or tenofovir (TDF) are recommended as less toxic and equally effective alternatives."

Mechanism of action Stavudine is a nucleoside analog of thymidine. It is phosphorylated by cellular kinases into an active triphosphate. Stavudine triphosphate inhibits HIV's reverse transcriptase by competing with the natural substrate, thymidine triphosphate. Reverse transcriptase is the enzyme the virus uses to make a DNA copy of its RNA in order to insert its genetic material into the host's DNA. Upon incorporation into the DNA strand, stavudine triphosphate causes termination of DNA replication.

Pharmacokinetics Absorption: Stavudine has rapid absorption and good oral bioavailability (F = 0.86). Distribution: Stavudine does not bind to proteins in the blood. Metabolism: The clearance of stavudine is affected minimally by hepatic metabolism. Oxidation and glucuronidation produce minor metabolites. Elimination: Stavudine is mostly eliminated in the urine and mostly in its unchanged form.

Drug interactions Simultaneous use of zidovudine is not recommended, as it can inhibit the intracellular phosphorylation of stavudine. Other anti-HIV drugs do not possess this property. Stavudine is not protein-bound nor does it inhibit the major cytochrome P450 isoforms. Thus, significant drug interactions with drugs metabolized through these pathways or drugs that are protein-bound are unlikely.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Stavudine

Start with the simplest possible case. Write down what Stavudine claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Stavudine before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Stavudine ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Stavudine

In research: Stavudine appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Stavudine in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Stavudine is common in secondary-school and first-year university syllabi. It links to neighbouring topics Dihydrofurans, Drugs developed by Bristol Myers Squibb, Hepatotoxins, so understanding it makes those chapters shorter.
In everyday life: Look for Stavudine outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Stavudine in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Stavudine means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Stavudine out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Stavudine in simple terms?

Stavudine (d4T), sold under the brand name Zerit among others, is an antiretroviral medication used to prevent and treat HIV/AIDS. It is generally recommended for use with other antiretrovirals.

Why does Stavudine matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Stavudine?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Stavudine.