Hepatitis C direct-acting antivirals: adherence, hepatitis B and interactions

How direct-acting antivirals work

Direct-acting antivirals block proteins hepatitis C needs to copy itself. Sofosbuvir inhibits the NS5B polymerase, and drugs such as velpatasvir inhibit NS5A. Combination tablets, such as sofosbuvir with velpatasvir, are taken once daily, commonly for 12 weeks, and are usually well tolerated, with headache and fatigue among the common effects.

This page picks up where screening ends: once infection is confirmed and treatment is prescribed, the nursing work shifts to preparation, adherence and interaction checks. Because the regimen is short and usually tolerated, the main avoidable causes of failure are missed doses and interacting medicines, both of which nurses are well placed to find.

Hepatitis B reactivation: test first, then watch

These drugs carry a boxed warning for hepatitis B reactivation in people with current or past hepatitis B infection. Clearing hepatitis C can allow hepatitis B to flare, and some cases have led to liver failure or death. Everyone should be tested for hepatitis B surface antigen and core antibody before starting.

Patients with evidence of hepatitis B are monitored during and after treatment. Teach them to report yellowing of the skin or eyes, dark urine, pale stools, abdominal pain or unusual tiredness, and make sure a positive hepatitis B result is visible to the treating team. A missing hepatitis B result before the first dose is worth raising.

Interactions: acid reducers, inducers and amiodarone

Velpatasvir absorption falls as stomach pH rises. For sofosbuvir-velpatasvir, the label advises separating antacids by four hours, limiting H2 blockers to specified timing, and avoiding proton pump inhibitors unless considered necessary, in which case a specific timing with food is used. Over-the-counter heartburn remedies are easy to miss, so ask specifically.

Enzyme inducers such as rifampin, carbamazepine and St John's wort can lower drug levels and are avoided. Amiodarone with sofosbuvir-containing regimens can cause serious symptomatic bradycardia, especially with beta blockers or heart disease; it is not recommended, and if unavoidable, cardiac monitoring is required. Warfarin and diabetes medicines may need adjustment as liver function improves.

The label's monitoring advice is concrete: if amiodarone cannot be avoided, it recommends a period of inpatient cardiac monitoring at the start of treatment, followed by daily heart rate checks for the first weeks, as the prescriber arranges. Report any slowing of the heart rate or new dizziness straight away rather than waiting for the next scheduled check, and make sure everyone caring for the patient knows the combination is in use.

Adherence and teaching for a short course

Teach the patient to take the tablet at the same time each day and to continue even when they feel well, without stopping unless the prescriber agrees. Plan for refills before running out, and identify barriers such as housing, substance use, work shifts or travel, because the course is short and interruptions matter.

Ask the patient to bring every medicine and supplement to each visit, including antacids and herbal products. Teach the bradycardia warning signs for those at risk: dizziness, fainting, chest pain, shortness of breath, unusual tiredness or confusion. Explain that cure does not protect against reinfection, so ongoing harm-reduction advice still applies.

Worked scenario: new antiviral, old heart medicine

A hypothetical patient about to start sofosbuvir-velpatasvir lists metoprolol, amiodarone and omeprazole among their medicines, and asks whether they can begin tomorrow. Options include starting as planned, telling them to stop amiodarone themselves, or flagging the regimen to the prescriber and pharmacist before the first dose.

Flagging before the first dose is correct. Amiodarone with a sofosbuvir regimen risks serious bradycardia, more so with a beta blocker, and omeprazole can reduce velpatasvir levels. Self-stopping amiodarone is unsafe because of its own indication. The prescriber decides whether to change drugs or arrange monitoring, and the nurse documents the concern.

Sources and further reading

DailyMed: Epclusa (sofosbuvir and velpatasvir) prescribing information. Boxed hepatitis B warning and testing, amiodarone bradycardia, acid reducer timing, enzyme inducers, mechanism and lab monitoring.

MedlinePlus: Sofosbuvir and velpatasvir. Daily dosing for the full course, hepatitis B warning signs, antacid and acid reducer spacing, side effects.