Sustiva (Efavirenz) — Patient Information for Australia

Sustiva is a medicine containing efavirenz, used to treat HIV (Human Immunodeficiency Virus). This guide is designed to be easy to read and practical. It explains how Sustiva works, how it’s taken, common safety points, and important interactions—so you can use your treatment more confidently.

Important: Individual treatment plans vary. Always follow the directions given by your healthcare team.

Basic product information

How Sustiva works (mechanism of action)

HIV uses an enzyme called reverse transcriptase to convert its genetic information into a form it can use to replicate inside human cells. Efavirenz belongs to the NNRTI group. It binds to reverse transcriptase at a specific site and blocks the enzyme’s function.

When reverse transcriptase is inhibited, HIV replication slows down, helping to reduce the amount of virus in the body. In combination with other HIV medicines, this supports long-term control of infection.

Pharmacokinetics (how your body handles efavirenz)

Pharmacokinetics describes absorption, distribution, metabolism, and elimination.

• Absorption: Efavirenz is absorbed after you take it by mouth.
• Distribution: It distributes widely throughout the body, including into tissues relevant to HIV.
• Metabolism: Efavirenz is primarily metabolised in the liver (mainly by the CYP450 enzyme system, particularly CYP2B6).
• Elimination: It is eliminated mainly through metabolic pathways and then cleared from the body.
• Half-life: Efavirenz has a relatively long half-life, which contributes to sustained drug exposure.

Because efavirenz is processed by the liver and can interact with other medicines, liver health and medication review are important.

Typical use and treatment context

Sustiva (efavirenz) is used as part of combination antiretroviral therapy (ART) for people living with HIV. Combination therapy helps:

• Reduce viral load (the amount of HIV in blood)
• Increase immune function (e.g., improving CD4 cell counts)
• Reduce the risk of resistance by using multiple drug mechanisms
• Improve long-term outcomes

Sustiva may be used in adult and paediatric regimens depending on local availability and clinical guidelines. Your healthcare team will decide the most appropriate regimen based on your history, resistance profile, and other health factors.

Timing: when and how to take Sustiva

Many people are advised to take efavirenz at night due to possible central nervous system (CNS) side effects (such as dizziness, vivid dreams, or drowsiness). Taking it at night can help you sleep through some effects.

• Typical guidance: Take Sustiva once daily, preferably at bedtime or in the evening.
• Try to take it consistently: Keep the same time each day to maintain steady drug levels.
• If you miss a dose: Take it as advised by your healthcare team or pharmacist. In general, don’t double up without guidance.

Practical tip: If you experience sleepiness or abnormal dreams, switching the dose to bedtime (if that matches your clinician’s advice) may reduce daytime impact.

Food interactions (including taking with meals)

Efavirenz absorption can be affected by meals. In general, people are advised to take efavirenz in a way that keeps absorption predictable.

• With food: Taking efavirenz with food may increase drug levels in some individuals.
• Fatty meals: Very high-fat meals may increase exposure. If you notice stronger side effects after eating, consider taking it with a lighter meal (or according to your local advice).
• Consistency matters: Aim for a consistent routine—e.g., always take with the same style of meal or always on an empty stomach if that’s what your healthcare team recommends.

Patient reminder: Follow the specific instruction provided with your medicine. If you’re unsure whether to take it with or without food, ask your pharmacist.

Alcohol and medicine interactions

Alcohol: Drinking alcohol may worsen side effects associated with efavirenz, especially dizziness, drowsiness, impaired coordination, and mood changes. Alcohol can also affect how well you tolerate the medicine overall.

Medicines that may interact with efavirenz: Because efavirenz is metabolised in the liver and can affect certain drug-metabolising pathways, it may interact with other medicines. This can change levels of efavirenz or the other medicine, which can reduce effectiveness or increase side effects.

Common categories to discuss with your healthcare team include:

• Anticonvulsants (e.g., carbamazepine, phenytoin, phenobarbital)
• Antimycobacterial medicines (including some medicines used for tuberculosis)
• Hormonal contraception (oral contraceptives may interact; additional or alternative methods may be recommended)
• Antifungals and antibiotics (various options may interact)
• Antidepressants and psychiatric medicines (due to metabolism and CNS effects)
• Anticoagulants/antiplatelets (some may be affected)
• Herbal supplements (notably St John’s wort)—often avoid due to interaction risk

Always check: Provide your pharmacist with a full list of medicines, including over-the-counter products and supplements. If you start or stop any medicine, tell your clinician.

Indications (what Sustiva is used for)

Sustiva (efavirenz) is indicated for the treatment of HIV infection as part of combination antiretroviral therapy.

It is typically used when building or maintaining an effective ART regimen in consultation with a specialist. Choice of regimen depends on factors such as viral resistance, prior treatments, co-existing conditions, and interaction potential.

Dosing: common regimens and how dosing is determined

Dose and formulation must be individualised. Your prescribed dose depends on factors including age, weight (in children), and whether you’re using particular combination products.

Adults: Efavirenz is commonly prescribed as a once-daily regimen.

• Typical adult dosing: A standard daily dose is used for many adults, with adjustments in certain situations.
• Bedtime dosing: Frequently advised to reduce CNS side effects.

Children and adolescents: Dosing may be weight-based. Your paediatric specialist will determine the dose and monitor tolerability and response.

Important: Do not change your dose or schedule without medical advice. If side effects occur, discuss options rather than stopping abruptly.

Safety profile: key risks and what to watch for

Most people tolerate efavirenz reasonably well, but side effects can occur. The safety profile includes:

Common side effects

• CNS effects: dizziness, drowsiness, vivid dreams, insomnia, headache
• Gastrointestinal symptoms: nausea, vomiting
• Skin changes: rash (often mild to moderate, but serious reactions are rare)

Serious and less common risks

• Severe skin reactions: Stop and seek urgent medical care if you develop blistering, peeling skin, or a widespread rash with fever or mouth sores.
• Mental health effects: Symptoms such as severe mood changes, confusion, or suicidal thoughts require immediate medical assessment.
• Liver problems: Efavirenz can affect the liver. Seek advice promptly if you notice jaundice (yellow eyes/skin), dark urine, severe fatigue, or upper abdominal pain.
• Seizures: Rarely, efavirenz may be associated with seizures in susceptible individuals.

Pregnancy and fertility considerations

Efavirenz has important considerations in pregnancy and for people who could become pregnant. Guidance may vary based on trimester and available alternatives. If pregnancy is possible, discuss contraception and risk-benefit considerations with your healthcare team.

Breastfeeding considerations

HIV management in infants depends on careful planning. Discuss breastfeeding recommendations with your clinician based on your viral suppression status and local guidance.

Practical use tips (to get the best results)

• Take consistently: Try not to miss doses. Viral control improves with adherence.
• Use bedtime timing if advised: This can reduce daytime CNS effects for many people.
• Manage early side effects: Dizziness or vivid dreams often improve after the first few weeks for some patients.
• Report troubling symptoms quickly: Particularly rash, mood changes, or signs of liver trouble.
• Keep a medicine list: Include doses and times; show it to every healthcare provider.
• Avoid interacting substances: Check before using herbal products, new antibiotics, antifungals, or seizure medications.

Alternative treatment options

ART regimens are chosen based on effectiveness, interactions, side effect profile, resistance patterns, and individual circumstances. Depending on what’s suitable for you, alternatives may include:

• Other NNRTIs (e.g., rilpivirine—where appropriate)
• Integrase strand transfer inhibitors (INSTIs) (a commonly used modern class)
• Protease inhibitors (often boosted in certain regimens)
• Combination fixed-dose products that simplify dosing

Note: The “best” alternative depends on your medical history and drug interactions. If you’re considering switching from Sustiva, discuss this with a specialist—changes should not be made abruptly.

Market and legal context for Australia

In Australia, HIV medicines are regulated under the Therapeutic Goods Administration (TGA) framework. Medicines such as efavirenz are supplied through legitimate channels and may be accessible via prescription medicines programs, specialist services, and pharmacy supply networks.

Access and reimbursement: Some patients may access ART through the Pharmaceutical Benefits Scheme (PBS) or other arrangements depending on criteria and treatment eligibility. Availability can vary by product form and prescribing requirements.

Quality and safety: For online pharmacy services, ensuring supply through authorised distributors and maintaining cold-chain requirements if relevant (not typically required for efavirenz) are key to patient safety. Always choose a pharmacy that provides clear product information and Australian regulatory compliance.

Recent guidance and evolving practice

HIV treatment guidelines continue to evolve. Clinicians regularly review:

• Switching to modern regimens when appropriate (to reduce side effects and improve tolerability)
• Interaction management with current medicines for conditions such as tuberculosis, epilepsy, hepatitis, and mental health
• Monitoring plans for viral load, CD4 counts, and relevant blood tests (including liver function)

If you’re already stable on efavirenz, changes may not be necessary unless side effects, interactions, or other clinical factors develop. If you’re starting ART, your clinician may consider newer options depending on your situation.

Delivery and availability (online pharmacy considerations in Australia)

Availability may depend on supply chains, pack sizes, and formulation. When ordering online in Australia, look for a process that clearly states:

• Product identification: brand, strength, and form
• Dispatch time: typical processing and delivery timeframes
• Shipping coverage: which states/territories are serviced
• Tracking: confirmation and tracking information for deliveries
• Storage information: guidance on how to keep the medicine (typically at controlled room temperature unless otherwise labelled)

Tip: If you plan travel or need uninterrupted therapy, order ahead to avoid delays.

FAQ about Sustiva (Efavirenz)

1) What is Sustiva used for?

Sustiva (efavirenz) is used as part of combination HIV treatment to control the virus and help your immune system recover.

2) How quickly does efavirenz start working?

Many people see a reduction in viral load within weeks, but the time to reach an undetectable level varies. Your clinician will monitor response with blood tests.

3) Should I take it on an empty stomach?

Follow the specific instructions provided with your medicine. Some people are advised to take efavirenz at a consistent time with or without food depending on tolerability and side effects.

4) Why is bedtime dosing often recommended?

Efavirenz can cause CNS effects such as dizziness or vivid dreams. Taking it at night can reduce disruption during the day by aligning with sleep.

5) Can I drink alcohol while taking Sustiva?

It’s best to limit alcohol, as it may increase drowsiness, dizziness, and impaired coordination. If you notice worsening side effects after drinking, avoid alcohol and speak with your healthcare team.

6) What medicines should I avoid or be careful with?

Efavirenz can interact with many medicines, including some seizure medicines, tuberculosis medicines, hormonal contraceptives, certain antibiotics/antifungals, antidepressants, and herbal products such as St John’s wort. Always check with a pharmacist.

7) What should I do if I miss a dose?

Contact your pharmacist or healthcare team for guidance. In general, don’t double up unless advised. Consistent dosing helps maintain viral control.

8) What rash symptoms require urgent attention?

Seek urgent medical care for severe rash, blistering, peeling skin, rash with fever, or sores in the mouth or eyes.

9) Are there any liver monitoring requirements?

Your clinician may request blood tests to monitor liver function—especially if you have liver disease, hepatitis, or symptoms suggestive of liver problems.

10) Can I switch off efavirenz?

Switching depends on your viral control, side effects, interactions, and resistance history. Do not stop or change ART without specialist guidance.

When to seek medical help urgently

Get urgent medical assistance if you experience:

• Severe allergic-type reactions (swelling of face/lips, difficulty breathing)
• Severe rash, blistering, or rash with fever
• Signs of liver injury (yellowing of skin/eyes, severe abdominal pain, dark urine)
• Severe dizziness/fainting, confusion, extreme mood changes, or suicidal thoughts
• Severe persistent vomiting or inability to keep medicine down

Summary: Sustiva (efavirenz) is an NNRTI used in combination ART to treat HIV. It works by blocking HIV reverse transcriptase and reducing viral replication. Many people are advised to take it at night to help minimise CNS side effects. Because efavirenz can interact with other medicines and may affect the liver, careful medication review and monitoring are important for safe use.