Chapter 36 — Antiviral Pharmacology — Module 4 — Hepatitis B and C Pharmacology
1. A 56-year-old man with chronic hepatitis B has been maintained on lamivudine for eight years by a prior provider. His HBV DNA, previously suppressed, is now rising, and genotypic resistance testing reports rtM204I/V plus rtL180M. A colleague proposes switching him to entecavir monotherapy. What is the most appropriate next step?
A) Continue lamivudine and add entecavir at the standard naive-patient dose
B) Switch to entecavir monotherapy, which retains a high resistance barrier regardless of prior therapy
C) Switch to tenofovir-based therapy because entecavir resistance is markedly increased on this mutational background
D) Add peginterferon alfa to lamivudine to overcome the resistance mutations
E) Switch to adefovir dipivoxil as the preferred agent for lamivudine resistance
ANSWER: C
Rationale:
The rtM204I/V plus rtL180M pattern is the signature of lamivudine resistance, and these substitutions also reduce entecavir binding affinity. On this background, only one or two additional mutations are needed for high-level entecavir resistance, so entecavir is a poor choice. Tenofovir disoproxil fumarate or tenofovir alafenamide retains full activity against lamivudine-resistant HBV and is the preferred switch.
Option A: Option A is incorrect: continuing lamivudine maintains the selective pressure that produced resistance, and standard-dose entecavir is compromised on this background.
Option B: Option B is incorrect: entecavir's high resistance barrier applies to treatment-naive patients; it is substantially lowered when lamivudine-resistance mutations are already present.
Option D: Option D is incorrect: adding peginterferon to a failing lamivudine regimen is not a recognized salvage strategy and does not address the resistant virus pharmacologically.
Option E: Option E is incorrect: adefovir has a low resistance barrier and dose-limiting nephrotoxicity and is not preferred; tenofovir is the appropriate choice.
2. A 67-year-old woman with chronic hepatitis B requires indefinite oral nucleos(t)ide therapy. She has stage 3 chronic kidney disease (eGFR 48 mL/min/1.73m²) and established osteoporosis on dual-energy X-ray absorptiometry. Both tenofovir formulations are being considered. Which choice best fits her clinical profile, and why?
A) Tenofovir alafenamide, because it delivers equivalent HBV suppression with less renal and bone toxicity than tenofovir disoproxil fumarate
B) Tenofovir disoproxil fumarate, because it is the only tenofovir formulation effective in chronic kidney disease
C) Tenofovir disoproxil fumarate, because tenofovir alafenamide is contraindicated when eGFR is below 60 mL/min/1.73m²
D) Either formulation, because renal and bone safety are identical between them
E) Lamivudine, because it avoids tenofovir-related toxicity entirely and has an equivalent resistance barrier
ANSWER: A
Rationale:
Tenofovir alafenamide achieves HBV suppression equivalent to tenofovir disoproxil fumarate at roughly one-quarter the systemic tenofovir exposure, with significantly better renal and bone safety parameters. In a patient with both chronic kidney disease and osteoporosis who needs lifelong therapy, this safety advantage makes tenofovir alafenamide the better-fitting choice.
Option B: Option B is incorrect: tenofovir disoproxil fumarate carries greater renal and bone toxicity; it is not uniquely effective in chronic kidney disease, and tenofovir alafenamide is in fact preferred here.
Option C: Option C is incorrect: tenofovir alafenamide is not contraindicated at this eGFR; it is generally the preferred formulation in patients with renal concerns.
Option D: Option D is incorrect: the two formulations differ meaningfully in renal and bone safety, which is the entire basis for choosing between them.
Option E: Option E is incorrect: lamivudine has a low resistance barrier, not one equivalent to tenofovir, and is not an appropriate first-line substitute.
3. A resident asks why sofosbuvir is regarded as having an almost absolute genetic resistance barrier compared with other direct-acting antiviral classes. Which explanation is correct?
A) Sofosbuvir is dosed at concentrations so high that resistant virus cannot survive
B) Sofosbuvir is always combined with three other agents, so no single drug faces selection pressure
C) Sofosbuvir targets a host enzyme that the virus cannot mutate
D) Sofosbuvir resistance requires loss of the nonstructural protein 5B (NS5B) active site, which is lethal to the virus
E) The only relevant resistance substitution, serine-282-threonine (S282T), imposes a severe fitness cost and rarely emerges clinically
ANSWER: E
Rationale:
Sofosbuvir resistance requires the NS5B substitution S282T, which severely impairs viral replicative fitness. Because the resistant variant is so disadvantaged, S282T essentially does not emerge or persist during clinical treatment, giving sofosbuvir its near-absolute resistance barrier.
Option A: Option A is incorrect: the barrier reflects the fitness cost of the resistance mutation, not supra-physiologic dosing that kills resistant virus.
Option B: Option B is incorrect: while sofosbuvir is used in combination, its individual high barrier derives from the S282T fitness cost, not merely from combination therapy.
Option C: Option C is incorrect: sofosbuvir targets the viral NS5B polymerase, not a host enzyme.
Option D: Option D is incorrect: resistance arises from a specific point substitution (S282T) with a fitness cost, not from wholesale loss of the active site.
4. A genotype 1a hepatitis C virus patient is being evaluated for elbasvir/grazoprevir, and the clinician orders baseline nonstructural protein 5A (NS5A) resistance-associated substitution (RAS) testing before prescribing. Which pharmacological property best explains why NS5A RAS testing meaningfully changes management with this regimen?
A) NS5A inhibitors are renally eliminated, so baseline resistance dictates dose reduction
B) NS5A inhibitors have a lower genetic resistance barrier than sofosbuvir, so baseline RAS can reduce efficacy and may mandate longer therapy with ribavirin
C) NS5A inhibitors require an acidic gastric environment, so RAS testing predicts absorption
D) NS5A RAS testing predicts hepatotoxicity rather than treatment efficacy
E) NS5A inhibitors act on a host transporter, so RAS reflects host rather than viral variation
ANSWER: B
Rationale:
NS5A inhibitors have a lower genetic resistance barrier than sofosbuvir. In genotype 1a, baseline NS5A RAS at positions such as 28, 30, 31, or 93 can reduce the efficacy of elbasvir/grazoprevir, which is why guidelines recommend RAS testing before this regimen and extending treatment to 16 weeks with ribavirin if relevant RAS are present.
Option A: Option A is incorrect: the rationale for RAS testing is the lower resistance barrier of NS5A inhibitors, not renal elimination driving dose reduction.
Option C: Option C is incorrect: RAS reflects viral sequence variation affecting drug binding, not gastric pH-dependent absorption.
Option D: Option D is incorrect: RAS testing predicts reduced antiviral efficacy, not hepatotoxicity.
Option E: Option E is incorrect: resistance-associated substitutions are viral, occurring in the NS5A protein, not host transporter variants.
5. A 52-year-old man has genotype 3 hepatitis C virus infection with compensated cirrhosis and has never received an NS5A inhibitor. You know that sofosbuvir/velpatasvir achieves sustained virological response at 12 weeks (SVR12) of only about 88 to 91% in this specific population, below the rate seen elsewhere. Where available, which regimen is preferred to maximize his chance of cure?
A) Sofosbuvir/velpatasvir for 8 weeks
B) Ledipasvir/sofosbuvir for 12 weeks
C) Elbasvir/grazoprevir for 12 weeks
D) Sofosbuvir/velpatasvir/voxilaprevir for 12 weeks
E) Peginterferon plus ribavirin for 24 weeks
ANSWER: D
Rationale:
Genotype 3 with cirrhosis is the most challenging contemporary HCV scenario. Because sofosbuvir/velpatasvir achieves only 88 to 91% SVR12 here, adding the protease inhibitor voxilaprevir — giving sofosbuvir/velpatasvir/voxilaprevir for 12 weeks — is the preferred approach in NS5A-inhibitor-naive genotype 3 cirrhotic patients where available, improving the likelihood of cure.
Option A: Option A is incorrect: an 8-week course is inadequate for genotype 3 with cirrhosis, where extended and intensified therapy is needed.
Option B: Option B is incorrect: ledipasvir/sofosbuvir has limited activity against genotype 3 and is not appropriate here.
Option C: Option C is incorrect: elbasvir/grazoprevir is a genotype 1 and 4 regimen and does not cover genotype 3.
Option E: Option E is incorrect: interferon-based therapy is obsolete, more toxic, and inferior to direct-acting antiviral regimens for this patient.
6. Four patients with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B are weighing finite peginterferon alfa therapy against indefinite oral nucleos(t)ide therapy. Based on established response predictors, which patient is the best candidate for peginterferon because they are most likely to achieve HBeAg seroconversion?
A) HBV genotype A, high baseline alanine aminotransferase (ALT), low baseline HBV deoxyribonucleic acid (DNA)
B) HBV genotype D, normal baseline ALT, high baseline HBV DNA
C) HBV genotype C, normal baseline ALT, decompensated cirrhosis
D) HBV genotype C, low baseline ALT, active autoimmune hepatitis
E) HBV genotype D, low baseline ALT, untreated major depression
ANSWER: A
Rationale:
Favorable predictors of response to peginterferon alfa include HBV genotype A or B, high baseline ALT (reflecting active immune activity against the virus), low baseline HBV DNA, and on-treatment HBsAg decline. The patient with genotype A, high ALT, and low HBV DNA matches these predictors and is the best candidate.
Option B: Option B is incorrect: genotype D, normal ALT, and high baseline HBV DNA are all unfavorable predictors of peginterferon response.
Option C: Option C is incorrect: genotype C is less favorable, and decompensated cirrhosis is a contraindication to peginterferon.
Option D: Option D is incorrect: low ALT is unfavorable, and active autoimmune hepatitis is a contraindication to interferon therapy.
Option E: Option E is incorrect: low ALT is unfavorable, and untreated major depression is a contraindication given the neuropsychiatric effects of interferon.
7. A patient about to begin a sofosbuvir-based regimen for hepatitis C virus is also taking a medication that strongly induces P-glycoprotein (P-gp). Which of the following co-medications is contraindicated because it would substantially lower sofosbuvir plasma concentrations and risk treatment failure?
A) Omeprazole at a dose of 20 mg daily
B) Atorvastatin at a moderate dose
C) Rifampin
D) Acetaminophen
E) Dolutegravir
ANSWER: C
Rationale:
Sofosbuvir is a substrate of the P-gp and breast cancer resistance protein (BCRP) transporters. Strong inducers of these transporters — rifampin, carbamazepine, and St. John's Wort — markedly reduce sofosbuvir plasma concentrations and are contraindicated because subtherapeutic exposure risks treatment failure.
Option A: Option A is incorrect: a proton pump inhibitor such as omeprazole 20 mg affects pH-dependent absorption of certain NS5A inhibitors, not P-gp-mediated sofosbuvir exposure, and is not the contraindicated inducer here.
Option B: Option B is incorrect: atorvastatin is a transporter-interaction concern with protease-inhibitor-containing regimens but is not a P-gp inducer that lowers sofosbuvir levels.
Option D: Option D is incorrect: acetaminophen does not induce P-gp and does not meaningfully reduce sofosbuvir concentrations.
Option E: Option E is incorrect: dolutegravir has minimal interaction with sofosbuvir-based regimens and is in fact a preferred HIV backbone option during HCV treatment.
8. Before starting direct-acting antiviral (DAA) therapy for hepatitis C virus, a patient's hepatitis B panel returns hepatitis B surface antigen (HBsAg) negative but antibody to hepatitis B core antigen (anti-HBc) positive. What is the appropriate hepatitis B management during HCV treatment for this serologic pattern?
A) Start tenofovir prophylaxis for all such patients before the DAA
B) Defer HCV treatment until anti-HBc becomes undetectable
C) Give hepatitis B vaccination and delay HCV therapy until seroconversion
D) No hepatitis B testing or follow-up is needed once HCV therapy begins
E) Monitor HBV deoxyribonucleic acid (DNA) during and after HCV therapy, reserving antiviral treatment for reactivation
ANSWER: E
Rationale:
An anti-HBc-positive, HBsAg-negative patient has resolved or occult HBV and a lower reactivation risk than an HBsAg-positive patient. The appropriate approach is to monitor HBV DNA during and after HCV DAA therapy, initiating HBV-active treatment only if reactivation occurs — distinct from the HBsAg-positive patient, who needs preemptive tenofovir-based therapy.
Option A: Option A is incorrect: routine preemptive tenofovir is reserved for HBsAg-positive patients; anti-HBc-positive, HBsAg-negative patients are managed with monitoring.
Option B: Option B is incorrect: anti-HBc reflects prior exposure and typically persists indefinitely, so waiting for it to clear would inappropriately deny HCV therapy.
Option C: Option C is incorrect: this serology indicates prior exposure rather than susceptibility, and HCV treatment should not be delayed for vaccination-driven seroconversion.
Option D: Option D is incorrect: this pattern carries a real, if lower, reactivation risk, so HBV DNA monitoring is required rather than no follow-up.
9. An HIV/HCV co-infected patient on a virologically suppressive regimen of atazanavir boosted with ritonavir is to begin glecaprevir/pibrentasvir. The pharmacist flags a contraindication. Which adjustment is most appropriate before starting HCV therapy?
A) Reduce the glecaprevir/pibrentasvir dose by half to offset the interaction
B) Switch the antiretroviral regimen to an integrase inhibitor such as dolutegravir before starting glecaprevir/pibrentasvir
C) Continue atazanavir/ritonavir and add ribavirin to counteract the interaction
D) Continue the current regimen unchanged, as no clinically relevant interaction exists
E) Increase the atazanavir dose to maintain HIV suppression during HCV therapy
ANSWER: B
Rationale:
NS3/4A protease inhibitors such as glecaprevir are sensitive CYP3A4 substrates. Ritonavir-boosted atazanavir raises glecaprevir exposure roughly 6-fold to unsafe levels, making the combination contraindicated. The correct step is to switch to a compatible antiretroviral regimen — an integrase inhibitor such as dolutegravir, raltegravir, or rilpivirine has minimal interaction — before initiating glecaprevir/pibrentasvir.
Option A: Option A is incorrect: glecaprevir/pibrentasvir is a fixed-dose combination not designed for dose reduction, and halving it would not safely or reliably correct the interaction.
Option C: Option C is incorrect: ribavirin does not neutralize the pharmacokinetic interaction; the unsafe glecaprevir exposure would persist.
Option D: Option D is incorrect: the interaction is clinically significant and formally contraindicated, so leaving the regimen unchanged is unsafe.
Option E: Option E is incorrect: increasing atazanavir would not address — and could worsen — the elevation of glecaprevir concentrations.
10. A patient who injects drugs achieved sustained virological response at 12 weeks (SVR12) after hepatitis C virus therapy one year ago. On routine annual screening, HCV ribonucleic acid (RNA) is again detectable, and genotyping shows a different genotype than the original infection. How should this finding be interpreted and managed?
A) This represents treatment failure, and the original regimen should be abandoned as ineffective
B) This indicates the original SVR12 was falsely reported and must be retracted
C) This is viral relapse from the original infection requiring immediate resistance testing of the prior strain
D) This is reinfection with a new strain; it does not negate the prior SVR12, and retreatment follows treatment-naive principles
E) This requires lifelong suppressive therapy because cure is no longer achievable after reinfection
ANSWER: D
Rationale:
Detectable HCV RNA after SVR12 in a person with ongoing exposure risk, especially with a different genotype, represents reinfection with a genetically distinct strain rather than relapse. Reinfection does not negate the SVR12 already achieved and is not treatment failure; retreatment follows the same principles as treatment-naive therapy.
Option A: Option A is incorrect: a new-genotype infection is reinfection, not failure of the prior regimen, which successfully cured the original strain.
Option B: Option B is incorrect: a genuine SVR12 remains valid; subsequent reinfection does not invalidate the earlier cure.
Option C: Option C is incorrect: a different genotype indicates reinfection rather than relapse of the original strain, so prior-strain resistance testing is not the issue.
Option E: Option E is incorrect: HCV reinfection remains curable with standard finite DAA therapy; lifelong suppression is not required.
11. A student asks how entecavir achieves such a high resistance barrier in treatment-naive chronic hepatitis B patients despite being a single agent. Which mechanistic feature best accounts for this?
A) It inhibits three distinct steps of HBV reverse transcription — base priming, reverse transcription of pregenomic RNA, and positive-strand DNA synthesis
B) It permanently silences covalently closed circular DNA (cccDNA) in the nucleus
C) It is a protease inhibitor that blocks polyprotein maturation at several cleavage sites
D) It boosts host interferon-stimulated gene expression to clear infected cells
E) It integrates into host DNA, preventing further viral transcription
ANSWER: A
Rationale:
Entecavir is a guanosine analogue that, after triphosphorylation, inhibits three distinct steps of HBV reverse transcription: base priming, reverse transcription of the pregenomic RNA, and synthesis of the positive HBV DNA strand. This multi-step inhibition contributes to its high resistance barrier in treatment-naive patients, where fewer than 1% develop resistance over five years.
Option B: Option B is incorrect: no nucleos(t)ide analogue, including entecavir, eliminates or permanently silences cccDNA, which is why therapy is generally indefinite.
Option C: Option C is incorrect: entecavir is a nucleoside reverse transcriptase inhibitor, not a protease inhibitor acting on polyprotein maturation.
Option D: Option D is incorrect: interferon-stimulated gene induction is the mechanism of peginterferon, not entecavir.
Option E: Option E is incorrect: entecavir does not integrate into host DNA; it acts by inhibiting reverse transcription.
12. A treatment-naive hepatitis C virus patient with compensated cirrhosis (Child-Pugh A) is to receive glecaprevir/pibrentasvir. The clinician recalls that the duration differs from the patient without cirrhosis. What is the appropriate treatment duration?
A) 6 weeks, because cirrhosis shortens the required exposure
B) 8 weeks, identical to a patient without cirrhosis
C) 12 weeks, because compensated cirrhosis extends the recommended duration
D) 16 weeks plus ribavirin, as required for all cirrhotic patients
Glecaprevir/pibrentasvir is given for 8 weeks in treatment-naive patients without cirrhosis but is extended to 12 weeks when compensated (Child-Pugh A) cirrhosis is present. Recognizing this duration adjustment is essential to achieving optimal SVR12 in cirrhotic patients.
Option A: Option A is incorrect: cirrhosis lengthens rather than shortens the recommended duration; 6 weeks is not a recognized course.
Option B: Option B is incorrect: 8 weeks applies to treatment-naive patients without cirrhosis, not to this cirrhotic patient.
Option D: Option D is incorrect: 16 weeks plus ribavirin is not the standard glecaprevir/pibrentasvir course for compensated cirrhosis; 12 weeks is appropriate.
Option E: Option E is incorrect: glecaprevir/pibrentasvir contains a protease inhibitor and is not used in decompensated cirrhosis, and 24 weeks is not its compensated-cirrhosis duration.
13. The hepatitis C virus nonstructural protein 5B (NS5B) RNA-dependent RNA polymerase is targeted by two mechanistically distinct drug classes. A clinician wants to identify which agent acts as an obligate chain terminator after incorporation, versus an allosteric inhibitor that binds away from the active site. Which statement correctly characterizes the chain-terminating class?
A) Non-nucleoside inhibitors are incorporated into the strand and terminate elongation
B) Both nucleotide and non-nucleoside inhibitors bind the same allosteric pocket
C) Nucleotide analogues bind an allosteric site and change polymerase conformation
D) Non-nucleoside inhibitors require intracellular triphosphorylation before incorporation
E) Nucleotide analogues such as sofosbuvir are incorporated and act as obligate chain terminators
ANSWER: E
Rationale:
NS5B is targeted by nucleotide analogues, which are incorporated into the growing RNA strand and act as obligate chain terminators (for example sofosbuvir), and by non-nucleoside inhibitors, which bind allosteric sites and alter polymerase conformation without incorporation. The chain-terminating class is the nucleotide analogues.
Option A: Option A is incorrect: non-nucleoside inhibitors act allosterically and are not incorporated into the strand.
Option B: Option B is incorrect: the two classes act at different sites — nucleotide analogues at the active site via incorporation, non-nucleosides at allosteric pockets.
Option C: Option C is incorrect: it is the non-nucleoside inhibitors, not nucleotide analogues, that bind allosterically and alter conformation.
Option D: Option D is incorrect: intracellular triphosphorylation and incorporation describe nucleotide analogues, not non-nucleoside inhibitors.
14. A patient is co-infected with HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV) and presents with a CD4 count of 140 cells/mm³. The team must sequence therapy across all three infections. What is the most appropriate initial priority?
A) Begin HCV direct-acting antiviral therapy immediately, deferring all HIV treatment
B) Optimize and suppress HIV with antiretroviral therapy and allow immune reconstitution before starting HCV direct-acting antiviral therapy
C) Treat HBV alone first and withhold both HIV and HCV therapy until HBV DNA is undetectable
D) Start peginterferon for HCV to leverage its activity against all three viruses
E) Treat HCV and stop the HBV-active antiretroviral backbone to simplify the regimen
ANSWER: B
Rationale:
With advanced immunodeficiency (CD4 below 200 cells/mm³), antiretroviral therapy should be optimized and HIV suppressed, allowing immune reconstitution before initiating HCV direct-acting antiviral therapy, since immune reconstitution itself improves HCV outcomes. The antiretroviral backbone (such as tenofovir-based therapy) simultaneously covers HBV, and it must be continued indefinitely.
Option A: Option A is incorrect: deferring HIV treatment in a patient with a low CD4 count is unsafe; HIV suppression should be prioritized first.
Option C: Option C is incorrect: HBV is covered by the HBV-active antiretroviral backbone alongside HIV therapy, so isolating HBV treatment while withholding HIV therapy is inappropriate.
Option D: Option D is incorrect: peginterferon is not a pangenotypic cure-all across these viruses and is not the preferred sequencing strategy; modern DAAs are used for HCV.
Option E: Option E is incorrect: stopping the HBV-active backbone risks catastrophic HBV reactivation and is the most dangerous possible move.
15. A hepatitis C virus patient on hemodialysis is being treated with glecaprevir/pibrentasvir. A consultant suggests adding ribavirin to intensify therapy. Why is ribavirin generally avoided in this dialysis patient?
A) Ribavirin is a strong P-glycoprotein inducer that lowers glecaprevir concentrations
B) Ribavirin requires an acidic gastric environment that dialysis abolishes
C) Ribavirin is hepatically eliminated and accumulates in hepatic impairment, not renal impairment
D) Ribavirin is renally eliminated and causes hemolytic anemia, a risk that is heightened in dialysis patients
E) Ribavirin antagonizes pibrentasvir, reducing the regimen's antiviral activity
ANSWER: D
Rationale:
Ribavirin is renally eliminated and causes dose-dependent hemolytic anemia. In patients with severe renal impairment or on dialysis, impaired clearance heightens this hemolytic risk, so ribavirin requires dose modification or avoidance and is generally not used in this population. Glecaprevir/pibrentasvir alone is already preferred and effective in dialysis patients.
Option A: Option A is incorrect: the concern is ribavirin's renal elimination and hemolytic toxicity, not P-glycoprotein induction lowering glecaprevir levels.
Option B: Option B is incorrect: ribavirin absorption is not the issue; its renal clearance and hemolytic effect are.
Option C: Option C is incorrect: ribavirin is renally, not hepatically, eliminated, which is precisely why dialysis patients are at increased risk.
Option E: Option E is incorrect: ribavirin does not antagonize pibrentasvir; the reason to avoid it is hemolytic anemia from renal accumulation.
16. A patient with HIV/hepatitis B virus (HBV)/hepatitis C virus (HCV) triple infection has just achieved sustained virological response at 12 weeks (SVR12) for HCV on a tenofovir-based antiretroviral regimen. The team is now reviewing the long-term plan. Which decision is essential to prevent a catastrophic complication?
A) Discontinue all antiviral therapy now that HCV is cured
B) Switch to an HBV-inactive antiretroviral regimen to reduce pill burden
C) Continue the HBV-active (tenofovir-based) antiretroviral backbone indefinitely
D) Stop the tenofovir component but continue the rest of the antiretroviral regimen
E) Replace tenofovir with lamivudine monotherapy for HBV coverage
ANSWER: C
Rationale:
After HCV cure in a triply infected patient, the HBV-active tenofovir-based antiretroviral backbone must be continued indefinitely, because it simultaneously suppresses HIV and HBV. Withdrawing HBV-active therapy is the most dangerous post-cure error and can precipitate catastrophic HBV reactivation and hepatic decompensation.
Option A: Option A is incorrect: HIV and HBV both require ongoing suppression; stopping all therapy would be hazardous.
Option B: Option B is incorrect: switching to an HBV-inactive regimen removes HBV suppression and risks reactivation, which is precisely the catastrophic outcome to avoid.
Option D: Option D is incorrect: tenofovir is the component providing HBV coverage, so stopping it specifically removes HBV suppression and invites reactivation.
Option E: Option E is incorrect: lamivudine monotherapy has a low resistance barrier and is inadequate to safely replace a tenofovir backbone for HBV in this setting.
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