Antiviral_part3_Flashcards

Question 1

What type of virus is Hepatitis C Virus (HCV)?

Answer 1

RNA virus.

Question 2

How many polyproteins does HCV encode, and how are they classified?

Answer 2

HCV encodes 10 polyproteins: 3 structural proteins and 7 nonstructural (NS) proteins, classified into 7 genotypes and several subtypes.

Question 3

Which HCV genotypes are most prevalent globally and in Egypt/Middle East?

Answer 3

Genotype 1 is most prevalent worldwide, and Genotype 4 is predominant in Egypt and the Middle East.

Question 4

What are the clinical findings and primary goal of treatment in HCV infection?

Answer 4

Clinical findings: Hepatitis, cirrhosis, and hepatocellular carcinoma. Primary goal: Viral eradication.

Question 5

Name the three categories of antiviral drugs used for HCV.

Answer 5

1. Direct-acting antiviral drugs (DAA). 2. Pegylated interferon (PEG-IFN) alpha. 3. Ribavirin.

Question 6

What is the mechanism of action of Direct-Acting Antiviral Drugs (DAAs)?

Answer 6

DAAs act as inhibitors of non-structural proteins (NS), achieving high virological cure rates (>90%).

Question 7

What factors determine drug selection in HCV treatment?

Answer 7

1. Presence of cirrhosis. 2. Viral genotype. 3. Previous failure of therapy.

Question 8

What is the duration of DAA therapy for HCV?

Answer 8

Treatment duration can range from 8, 12, 16, or 24 weeks (2 to 6 months).

Question 9

What are the four current classes of DAAs, and what do they target?

Answer 9

Defined by their mechanism of action (MOA) and specific target.

Question 10

Name one class of DAAs and its key drugs.

Answer 10

NS3/4A protease inhibitors: Asunaprevir, Glecaprevir, Grazoprevir, Paritaprevir, Simeprevir, Voxilaprevir (e.g., Previr suffix).

Question 11

What type of virus is Hepatitis B Virus (HBV), and what are its clinical findings?

Answer 11

Type: DNA virus. Clinical findings: Hepatitis, cirrhosis, and hepatocellular carcinoma.

Question 12

What are the main drugs used to treat HBV infection?

Answer 12

1. Interferons (Interferon-alfa, Pegylated interferon-alfa). 2. Nucleoside/Nucleotide analogs.

Question 13

Name some examples of nucleoside and nucleotide analogs for HBV treatment.

Answer 13

Nucleoside analogs: Lamivudine, Entecavir, Telbivudine. Nucleotide analogs: Adefovir dipivoxil, Tenofovir disoproxil, Tenofovir alafenamide.

Question 14

What is the mechanism of action of nucleoside/nucleotide analogs?

Answer 14

Require intracellular phosphorylation to be active. They inhibit HBV DNA polymerase, causing DNA chain termination.

Question 15

What type of virus is HIV, and to which family does it belong?

Answer 15

Type: RNA virus. Family: Retroviruses.

Question 16

What are the structural components of HIV?

Answer 16

Enveloped virus with a capsid containing two copies of RNA strands and associated protein (e.g., reverse transcriptase).

Question 17

How does HIV replicate?

Answer 17

HIV converts RNA to DNA (via reverse transcriptase), integrates into the host genome, and then produces new viral RNA.

Question 18

How many classes of antiretroviral drugs are used to treat HIV, and what is their primary goal?

Answer 18

Six classes, each targeting a specific step in the viral life cycle.

Question 19

What is the primary toxicity of nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)?

Answer 19

Mitochondrial toxicity due to inhibition of mitochondrial DNA polymerase gamma, potentially causing lactic acidosis with hepatic steatosis.

Question 20

Name the NRTIs and their key side effects (S/E).

Answer 20

1. Emtricitabine: Minimal side effects. 2. Lamivudine: Minimal side effects. 3. Tenofovir: Renal insufficiency and osteoporosis. 4. Abacavir: Hypersensitivity reaction (associated with HLA B*5701 allele). 5. Zidovudine: Macrocytic anemia and neutropenia. 6. Stavudine: Peripheral neuropathy, pancreatitis, lipoatrophy. 7. Didanosine: Peripheral neuropathy, pancreatitis, lipoatrophy.

Question 21

What is a key metabolic feature of NRTIs?

Answer 21

NRTIs are not metabolized by cytochrome P450 enzymes, leading to minimal drug interactions.

Question 22

What is the mechanism of action of non-nucleoside reverse transcriptase inhibitors (NNRTIs)?

Answer 22

NNRTIs bind to and inhibit the reverse transcriptase enzyme, preventing viral RNA replication.

Question 23

Name common NNRTIs and their key side effects.

Answer 23

1. Nevirapine: Rash and hepatotoxicity. 2. Efavirenz: CNS symptoms (dizziness, impaired concentration, nightmares, insomnia, psychosis episodes). 3. Etravirine, Rilpivirine, Delavirdine: Generally milder side effects.

Question 24

How are NNRTIs metabolized, and what are their interactions with CYP450?

Answer 24

Metabolized by CYP450. Nevirapine acts as an inducer. Delavirdine acts as an inhibitor. Efavirenz and Etravirine are mixed inducers and inhibitors.

Question 25

What is a major limitation of NNRTIs regarding resistance?

Answer 25

NNRTIs have a low genetic barrier to resistance, meaning resistance may arise from a single mutation.

Question 26

What are the mnemonic abbreviations for NRTIs?

Answer 26

Sta/Di/Zido/Aba/Te/La/Emtri (Stavudine, Didanosine, Zidovudine, Abacavir, Tenofovir, Lamivudine, Emtricitabine).

Question 27

What is the role of pharmacological enhancers or boosters in antiretroviral therapy?

Answer 27

They: 1. Combine with certain antiretroviral drugs. 2. Act as inhibitors of CYP450. 3. Increase plasma concentrations of antiretroviral drugs. 4. Enhance drug exposure and decrease dosing frequency.

Question 28

What is Cobicistat, and what is its primary function?

Answer 28

Cobicistat has no direct antiretroviral activity but is used as a pharmacological enhancer. Example: Elvitegravir-cobicistat.

Question 29

What is Ritonavir, and how is it used in therapy?

Answer 29

Ritonavir is a protease inhibitor used at low doses to maintain therapeutic levels of other protease inhibitors in combination therapy.