Antiviral Flashcards
1
Q
Aciclovir
Indications
A
- HSV including suppression
- Genital herpes simplex
- Varicella Zoster (chickenpox) treatment
- Herpes Zoster (Shingles) treatment
- NB- for extremes of weight calculate IBW
2
Q
Aciclovir
MOA
A
- Aciclovir is a synthetic purine nucleoside analogue with inhibitory activity against HSV and VSV
- The enzyme Thymidine Kinase (TK) of normal, uninfected cells does not use aciclovir effectively as a substrate, hence toxicity of mammalian host cells is low
- However, TK encoded by HSV/VSV converts aciclovir, a nucleoside analogue which is furhter converted to a diphosphate and finally to the triphosphate by cellular enzymes
- Aciclovir triphosphate interferes with the viral DNA polymerase and inhibits viral DNA replication with resultant chain termination following its incorporation into the viral DNA
3
Q
Aciclovir
Warnings
A
- Cautioned in
- Elderly- risk of neurological reactions in adults
- Maintain adequate hydration
4
Q
Aciclovir
Adverse effects
A
- Psychiatricand CNS- Headache, dizziness, confusion, convulsions
- GI- N&V, diarrhoea, abdo pain
- Skin- Rashes, pruritus
- Blood- uncommon but leucopenia, thrombocytopenia
5
Q
Aciclovir
Interactions
A
- Aciclovir is eliminated primarily unchanged in the urina via active renal tubular secretion
- Any drugs administrered concurrently that compete with this mechanism may increase aciclovir plasma concentrations
- Theophylline
6
Q
Ritonavir
Indications
A
- HIV infection in combination with other anti-retroviral drugs
- Low dose booster to increase effect of other protease inhibitors
7
Q
Ritonavir
MOA
A
- Ritonavir is an orally active peptidomimetic inhibitor of the HIV-1 and HIV-2 aspartyl proteases.
- Inhibition of HIV protease renders the enzyme incapable of processing the gag-pol polyprotein precursor which leads to the production of HIV particles with immature morphology that are unable to initiate new rounds of infection.
- Ritonavir has selective affinity for the HIV protease and has little inhibitory activity against human aspartyl proteases.
- Ritonavir was the first protease inhibitor (approved in 1996) for which efficacy was proven in a study with clinical endpoints.
- However, due to ritonavir’s metabolic inhibitory properties its use as a pharmacokinetic enhancer of other protease inhibitors is the prevalent use of ritonavir in clinical practice
8
Q
Ritonavir
Warnings
A
- Contraindicated in
- Acute porphyrias
- Cautioned in
- Haemophillia- increased risk of bleeding
- Cardiac conduction disorders- QT prolongation
- Pancreatitis
9
Q
Ritonavir
Adverse effects
A
- Blood- Decreased WCC, thrombocytopenia, decreased neutrophils
- Immune- Hypersensitivity
- Metabolism- Oedema, dehydration, hypercholesterolaemia
- CNS- Peripheral neuropathy, dizziness,
- Eyes- Visual disturbances
- Vascular- HTN, hypotension
- Respiratory- Pharyngitis, cough
- GI- general issues, mouth ulcers, pancreatitis, e- imbalance
- Hepatic- Hepatitis
10
Q
Ritonavir
Interactions
A
- Ritonavir is a potent CYP inducer
11
Q
Oseltamivir
Indications
A
- Prevention of influenza
- Treatment of influenza
12
Q
Oseltamivir
MOA
A
- Oseltamivir phosphate is a pro-drug of the active metabolite
- The metabolite is a selective inhibitor of influenza virus neuraminidase enzymes, which are glycoproteins found on the virion surface
- Neuraminidase enzyme activity is important both for viral entry into uninfected cells and for the release of recently formed virus particles from infected cells and for the further spread of infectious virus in the body
13
Q
Oseltamivir
Adverse effects
A
- Infections- HSV, Upper RTI
- CNS- Headache, insomnia
- GI- N&V, abdo pain
- Hepatic- Elevated LFTs
- Serious ADRs
- Anaphylaxis
- Hepatic disorders- jaundice
- Angioneurotic oedema
- SJS + Toxic epidermal necrolysis- Rash
- GI bleeding
- Neuropsychiatric disorders
14
Q
A
