Upload
aniah-azmi
View
65
Download
3
Tags:
Embed Size (px)
DESCRIPTION
Pharmacology of the anti-virals and their use in ophthalmology. Mainly on their principals and mechanism of action. * This is short presentation as it was a small part of our medical retina team presentation where the topic was on CMV Retinitis.
Citation preview
Pharmacology
Aciclovir, Valganciclovir & GanciclovirBy Noor Aniah Azmi (MBBCh Cairo, Egypt)
Medical retina
team
presentation
Objectives
oUnderstand about each of the antiviral
oUnderstand the indications for their use
o Learn about the virus life cycle
Now, let’s learn about the
virus life cycle
Ganciclovir
Synthetic guanosine analogue
First antiviral approved for CMV treatment
How does it work?
How come it doesn’t work in some cases?
Mutations UL97 – encodes of CMV phospotransferase
.
Which virus does it attack?
In what preparations do they exist?
Zirgan ointment 0.15% - ophthalmic gel Cytovene 500 mg
What are the effects of the body on the drug?
Absorption: • Oral – very limited• t ½ : 2-6 hours
Distribution: All tissues• Especially CSF and ocular tissue
Excretion: 80-90% unchanged in urine
When do we use Ganciclovir?
1. Herpes Epithelial Keratitis Ganciclovir Gel 0.15% (Zirgan)
2. CMV Retinitis
Initial: IV 5mg/kg BD for 14-21 daysMaintenance: IV 5mg/kg OD or IV 6 mg/kg OD for 5 days/week
What are the side effects?
Bone marrow supression Neutropenia Granulocytopenia
TOXICITY Potential carcinogen Teratogen Inhibits spermatogenesis
ValganciclovirProdrug of Ganciclovir
Taken orally
Changed to Ganciclovir by intestinal/hepatic esterase
In what preparations do they exist?
Valcyte Tablet 450 mg Valcyte Oral Solution 50 mg/mL
What are the effects of the body on the drug?
Absorption: • Well-absorbed especially with fatty meals
Distribution: • Well distributed especially CSF and ocular tissues
Metabolism: • In liver & intestine changed to Ganciclovir
Excretion: 80-90% in urine
When do we use Valganciclovir?
CMV Retinitis
Initial: Oral 900 mg BD x 21 daysMaintenance: Oral 900 mg OD
AciclovirMost commonly used antiviral
Commonly used for HSV and Chickenpox
How does it work?
How come it doesn’t work in some cases?
• Deficient viral thymidine-kinase
• Mutations to viral thymidine-kinase or DNA polymerase
.
Which virus does it attack?
Herpes-simplex 1 Herpes-simplex 2 Varicella-zoster virus Epstein-Barr virus Cytomegalovirus
Most activity
In what preparations do they exist?
Zovirax ointment 3% Tablet Aciclovir 200 mg / 400 mg
What are the effects of the body on the drug?
Absorption: • Poor water-soluble• Poor oral bioavailability
Distribution: High distribution rate• T ½: 3 hours
Metabolism: Small amounts – liver
Excretion: 62-90% unchanged in urine
When do we use Aciclovir?
Herpes-Zoster Ophthalmicus Herpex Simplex Blepharitis
Herpes keratitis
What are the side effects?
Systemic Nausea, vomiting Encephalopathy IV
Local SPK Allergy