11-30 Treatment of Hepatitis DSA - Pharm Flashcards
What are the drug classes for treatment of HBV?
Interferon alfa
Nucleoside/Nucleotide Analogs (NAs)
What are the advantages of interferon alfa versus NAs?
finite duration of treatment, resistance is not a problem, responses are more durable.
What are the disadvantages of interferon-alfa versus NAs?
side effects; cannot be used in patients with decompensated disease.
What is the MOA for Interferon alfa?
cytokine which exhibits complex antiviral, immunomodulatory, and anti-proliferative actions.
Inhibits viral penetration, translation, transcription, protein processing, maturation, and release.
Enhanced phagocytic activity of macrophages and augmentation of proliferation/survival of cytotoxic T-cells.
What is the Pk of interferon alfa?
Interferon alfa-2a, alfa-2b (SubQ or IM) – t1/2 2-5 hours; filtered by glomerulus, proteolytic degradation during tubular reabsorption.
What is pegylated interferon? Why is it used?
Pegylated interferon (peginterferon, Peg-IFN): polyethylene glycol complexed (non-toxic polymer excreted in the urine); always given subcutaneously;
slower clearance (30% renal – dose adjust in impairment),
longer t1/2 of 40 hours,
steadier concentration allows for less frequent dosing (once-weekly compared to daily or thrice-weekly dosing).
What is the clinical use of interferon alfa?
chronic HBV and chronic HCV (see clinical pharmacology section below).
What are the ADRs for interferon alfa?
- 30% of patients experience flu-like illness (headache, fever, chills, myalgias, malaise) within first week of therapy; occurs ~6 hours following dose (generally resolves with continued therapy).
- Transient increase in hepatic enzymes (first 8-12 weeks) à common in treatment responders.
- Chronic therapy – neurotoxicity (mood disorders, depression, somnolence, confusion, seizures), myelosuppression, profound fatigue, weight loss, rash, cough, myalgia, alopecia, tinnitus, reversible hearing loss, retinopathy, pneumonitis, possibly cardiotoxicity.
What are the contraindications for interferon alfa?
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CIs: hepatic decomposition, autoimmune disease (can cause induction of autoantibodies), history of cardiac arrhythmia, pregnancy.
- Cautions: psychiatric disease, epilepsy, thyroid disease, ischemic cardiac disease, severe renal insufficiency, and cytopenia.
What are the DDIs for interferon alfa?
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DDIs: may increase levels of theophylline and methadone.
- Co-administration not recommended with didanosine (increased risk of hepatic failure) or zidovudine (exacerbates cytopenias).
What is the MOA for NAs?
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Nucleoside/Nucleotide Analogs (NAs)
- General MOA: interfere with viral replication.
What is the general Pk for NAs?
renal elimination and must be dose adjusted in renal impairment. Long t1/2 allowing once-daily dosing.
What are the advantages of NAs compared to interferon?
- Advantages vs. Interferon: PO administration (tablets or solution), better tolerated, higher response rate, can be used for chronic therapy or in patients with significant liver disease.
What are the disadvantages of NAs?
- Disadvantages: sustained response limited after therapy discontinuation, resistance can be problematic, some agents cause peripheral neuropathy, general warning for lactic acidosis and hepatic steatosis (mitochondrial dysfunction).
Name some NAs.
Adefovir dipivoxil
Entecavir
Lamivudine
Telbivudine
Tenofovir
What is the MOA for Adefovir dipivoxil?
adenine nucleotide analog; inhibits HBV DNA polymerase, chain termination after incorporation into viral DNA.
What is the therapeutic use for adefovir dipivoxil?
- Active against a wide range of DNA and RNA viruses, including HBV, HIV, and herpesviruses.
- Not recommended as first-line agent for HBV due to slow response and low likelihood of HBeAg seroconversion.
What are the ADRs for adefovir dipivoxil?
- headache, diarrhea, abdominal pain; potential nephrotoxicity (dose-dependent).
What is the resistance to adefovir dipivoxil?
- Resistance: early development low, but up to 30% after 4 years.
No cross-resistance with lamivudine or entecavir
What is the MOA for Entecavir?
guanosine nucleoside analog; inhibits DNA polymerase (base priming, reverse transcription of negative strand, and viral DNA synthesis).
What is the therapeutic use for Entecavir?
- recommended first-line therapy for HBV; exhibits good viral suppression and normalization of liver enzymes with slowing of liver damage.
What are the ADRs for Entecavir?
well-tolerated; side effects include headache, fatigue, dizziness, nausea, rash, fever
What is the resistance for entecavir?
rare (< 1% at 4 years).
What is the MOA for lamivudine (3TC)?
cytosine analog; inhibits DNA polymerase, competes for incorporation into viral DNA, causes chain termination.
What is the therapeutic use for Lamivudine?
- HIV treatment regimens.
- Rapidly suppresses HBV, but not recommended as first-line therapy due to high rate of resistance (15-30% at 1 year and 70% at 5 years) and progressive liver disease.
What are the ADRs for lamivudine?
excellent safety profile, including use during pregnancy;
side effects are rare, but include
headache, nausea, diarrhea, myalgia, and dizziness;
co-infection with HIV may increase risk of pancreatitis.
What is the resistance to lamivudine like?
cross-resistance with entecavir may occur; often used in combination with adefovir to combat resistance
What is the MOA for Telbivudine?
: thymidine nucleoside analog; inhibits DNA polymerase (competitive inhibition), incorporates into viral DNA, causes chain termination
What is the therapeutic use of telbivudine?
- Rapidly suppresses HBV and causes HBeAg seroconversion with reduced liver damage, but not recommended as first-line therapy due to high rate of resistance (22%), which increases after one year of therapy.
What are the ADRs for Telbivudine?
well-tolerated; side effects are generally mild and may include fatigue, headache, cough, abdominal pain, diarrhea, increased creatine kinase levels, nausea, and vomiting
What are the CIs for Telbivudine?
- avoid concurrent use with interferon alfa due to increased risk of peripheral neuropathy.
What is the resistance for telbivudine like?
cross-resistance with lamivudine
What is the MOA for tenofovir?
nucleotide analog of adenosine; competitively inhibits DNA polymerase, incorporates into viral DNA, causes chain termination
What is the therapeutic use of tenofovir?
- Recommended first-line therapy for HBV; treats lamivudine- and entecavir-resistant isolates, but exhibits reduced activity against adefovir-resistant strains.
- HIV treatment regimens.
What are the ARDs associated with Tenofovir?
nausea, diarrhea, vomiting, decreased bone mineral density (consider calcium and vitamin D supplementation and monitor bone density in long-term use).
What is the resistance like for tenofovir?
- Resistance: rare, less frequent than with adefovir.
What are the drug classes for Tx of HCV?
Direct-Acting Antivirals
Interferon alfa
Ribavirin
Protease inhibitors
What are the drugs in the diract-acting antivirals (DAA) class?
Daclatasvir
Lepidasvir-sofosbuvir
Ombitasvir-paritaprevir-ritonir + dasabuvir
Sofosbuvir
Simeprevir
What is the MOA for daclatasvir?
binds N-terminus of HCV nonstructural protein 5A (NS5A), inhibits viral RNA replication and virion assembly
What is the Pk for Daclatasvir?
metabolized via CYP3A (caution DDIs; concurrent use of strong CYP3A inducers is CI
What is the therapeutic use for Daclatasvir?
HCV
What are the ADRs for Daclatasvir?
fatigue, headache, nausea, diarrhea, increased serum lipase (all ADRs are from combination trials with sofosbuvir).
What is the cost for daclatasvir?
Cost: $147,000 for 12-weeks of treatment with daclatasvir and sofosbuvir
What is the MOA for ledipasvir?
- Ledipasvir-sofosbuvir (Harvoni) FDA approved October 10, 2014 in a combined formulation; the following information is for ledipasvir.
MOA: inhibits HCV NS5A protein necessary for viral replication; also acts as a chain terminator
What is the Pk for ledipasvir?
oxidative metabolism – mechanism unknown
What is the therapeutic use for ledipasvir?
HCV
What are the ADRs for ledipasvir?
fatigue, headache, insomnia, nausea, diarrhea, increased serum lipase.
What is the cost for ledipasvir?
Cost: $94,500 for 12-weeks of treatment
What is the MOA for ombitasvir-paritaprevir-ritonavir + dasubavir?
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MOA: distinct among the antiviral agents combined.
- Ombitasvir – inhibits HCV NS5A, interferes with viral RNA replication and virion assembly.
- Paritaprevir – inhibits HCV NS3/4A protease, interferes with HCV coded polyprotein cleavage necessary for viral replication.
- Dasabuvir – inhibits HCV RNA-dependent RNA polymerase necessary for viral replication.
- Ritonavir – no activity against HCV; used for its potent CYP3A inhibitory effects which increases plasma concentrations of paritaprevir and overall drug exposure.
What is the Pk and therapeutic use for ombitasvir-paritaprevir-ritonavir + dasubuvir?
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PK: CYP metabolism; must use caution and consider DDIs.
- Ombitasvir – amide hydrolysis and oxidative metabolism; excreted in feces.
- Paritaprevir – CYP3A4 metabolism; excreted in feces.
- Dasabuvir – CYP2C8 & 3A4 metabolism; excreted in feces.
- Ritonavir – CYP3A4 & 2D6 metabolism; excreted in feces.
- Therapeutic Use: HCV
What are the ADRs associated with ombitasvir-paritaprevir-ritonavir + dasabuvir? What is the cost?
- ADRs: fatigue, headache, nausea, pruritus, skin reactions, insomnia, and asthenia; elevations in serum alanine aminotransferase (ALT).
- Cost: $83,319 for 12-week supply.
What is the MOA for sofosbuvir?
- Sofosbuvir (Sovaldi) FDA approved December 6, 2013.
- MOA: inhibits HCV NS5B RNA dependent RNA polymerase (essential for viral replication), acts as chain terminator
What is the Pk for sofosbuvir?
- PK: 80% excreted in the urine, substrate of P-glycoprotein
What is the therapeutic use for sofosbuvir? ADRs?
- Therapeutic Use: HCV
- ADRs: fatigue, headache, insomnia, pruritus, nausea, diarrhea, flu-like symptoms, anemia, neutropenia, weakness, myalgia
What is the cost for sofosbuvir?
Cost: $84,000 for 12-week supply
What is the MOA for simeprevir?
- Simeprevir (Olysio) FDA approved November 22, 2013.
- MOA: inhibits HCV NS3/4A protease (essential for viral replication)
What is the Pk for simeprevir? Therapeutic use?
- PK: CYP3A4 oxidative metabolism, excreted in feces
- Therapeutic Use: HCV
What are the ADRs with simeprevir?
- ADRs: skin rash, pruritus, nausea, increased serum bilirubin, myalgia
What are the DDIs for simeprevir?
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DDIs: avoid with CYP inducers (rifampin) which will decrease simeprevir levels
- May increase concentration of other CYP3A4 substrates (i.e. statins)
What is the cost for simeprevir?
Cost: $66,360 for 12-week supply
What is the MOA for ribavirin?
- Ribavirin
- MOA: guanosine analog; interferes with guanosine triphosphate synthesis (inhibits capping of viral mRNA); inhibits initiation/elongation of RNA resulting in inhibition of viral protein synthesis.
What is the therapeutic use for ribavirin?
- Chronic HCV, in combination with direct-acting antivirals.
- Influenza A and B, parainfluenza, respiratory syncytial virus (RSV), paramyxoviruses, and HIV-1
What are the ADRs for ribavirin?
- ADRs:
Dose dependent hemolytic anemia (10-20%), depression, fatigue, nausea, rash, insomnia
What are the contraindications/CIs for ribavirin?
anemia, end-stage renal failure, ischemic vascular disease, pregnancy (pregnant women and their partners);
pregnant women should not directly care for patients receiving aerosolized ribavirin.
Ribavirin is teratogenic, embryotoxic, oncogenic, and possibly gonadotoxic
What are 2 protease inhibitors? Are they still recommended for HCV treatment?
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Protease Inhibitors (PIs)
- Telaprevir & Boceprevir (no longer recommended in guidelines – FYI only)