Antivirals, Antifungals and NSAIDs Flashcards
What is an antiviral
Medications that help the body fight off certain viruses
Can be a preventative measure
Why are antiviral drugs not commonly used in veterinary
Limited safety and efficacy in animals
Drugs that negatively affect the virus often negatively affect the host
Antivirals that only inhibit one step are temporary
Name the 2 antiviral treatment approaches and give an example
- Viral enzyme inhibition
- Immune response enhancement
example - interferon, inhibits viral synthesis In infected cells
Name the antiviral which is used against herpesvirus in birds
Acyclovir
Name the antiviral which is used against herpesvirus in cats
Famciclovir
Name the antiviral used for ocular herpes
Trifluridine
Name the antiviral used for retroviruses (FeLV, FIV)
Zidovudine
Name a broad-spectrum antiviral and which families of viruses it is effective against
Ribavirin
Adenoviruses, herpesviruses, rotaviruses and retroviruses
What is a viricide and give an example
Viricides - destroy virus external to host
Example - Virkon
Name the 5 main classes of antifungals
- Azoles
- Allylamines
- Polyenes
- Pyrimidine analogues
- `Cellular toxin’
How do azoles work against fungi and give some examples
Inhibit cytochrome P450-dependant synthesis of ergosterol in the fungal cell membrane
Examples - itraconazole, ketoconazole
How do allylamines work against fungi and give an example
Inhibit the synthesis of ergosterol in fungal cells via inhibiting the enzyme squalene epoxidase
example - terbinafine
Why does the fungal cell wall becoming deficient in ergosterol cause fungal cell death
It causes toxic products to accumulate causing cell death
How do polyenes work against fungi and give some examples
Polyene binds to sterols (ergosterol) in the fungal cell membrane
Causes physical change, pores form and cell contents leak out => cell death
Examples - amphotericin B, nystatin
How to pyrimidine analogues work against fungi and give an example
Example - 5-fluorocytosine
5-fluorocytosine is converted to 5-fluorouracil by fungo cells
Results in inhibition of DNA and RNA synthesis
Mammalian cells are not affected
How do cellular toxins work against fungi and give examples
Are not specific to fungi
- Silver sulfadiazine => releases silver in conc. toxic to bacteria and fungi
- Chlorhexidine (Hibiscrub) => binds to skin and provides a protective layer
- Virkon - oxidises sulphur bond in proteins disrupting function of cell membranes
Name some antifungals used for otitis externa
Micoconazole
Nystatin
Name some antifungals used for Malassezia skin infections
Miconazole shampoo
Intraconazole - off licence in dogs, oral
Chlorhexidine
Climbazole wipes
NB. do NOT use ketoconazole in cats
Name some antifungals used for dermatophytosis in cats and dogs
Itraconazole - off licence in dogs, oral
Ketoconazole - DONT use in cats, oral
Enilconazole - off licence in cats, skin rinse
Miconazole - shampoo, adjunctive treatment
Chlorhexidine - ineffective on its own, synergistic with miconazole
Name some antifungals used for dermatophytosis in rabbits and small mammals
All are off licence
Itraconazole - oral
Enilconazole - skin rinse
Miconazole - shampoo, adjunctive treatment
Chlorhexidine - used with miconazole
Name some antifungals used for dermatophytosis in horses
Enilconazole - skin rinse
Miconazole - off licence shampoo
Name an anti-fungal used for fungal keratitis in horses
Clotrimazole - off licence cream
Name an anti-fungal used for dermatophytosis in cattle
Enilconazole - off licence skin rinse
What antifungals are licensed in non food producing birds
Itraconazole
Voriconazole - expensive
What anti fungal is used in reptiles for fungal dermatitis
Itraconazole - off licence
Name some NSAIDs commonly used in small animal practice (x5)
Meloxicam
Carprofen
Robenacoxib
Firocoxib
Grapiprant (galliprant trade name)
Name some NSAIDs commonly used in farm animal practice (x2)
Meloxican
Ketoprofen
Name some NSAIDs commonly used in equine practice (x3)
Phenylbutazone (bute)
Flunixin meglumine
Meloxicam
What type of drug are most NSAIDs
Cyclo-oxygenase (COX) inhibitors
How do COX inhibitors work as NSAIDs
Inhibit the COX enzymes and therefore inhibit prostanoid synthesis in inflammatory cells
Inhibit COX2 isoform which is crucial for their anti-inflammatory, analgesia and antipyretic effects
How do COX inhibitors have an anti-inflammatory action
The decrease in prostaglandin E2 (PGE2) and prostacyclin (PGI) reduces vasodilation and indirectly reduces oedema
How do COX inhibitors have an analgesic action
Decreased prostaglandin means reduced sensitisation of nociceptive nerve endings to inflammatory mediators (such as bradykinin)
How do COX inhibitors have an anti-pyretic action
NSAIDs prevent interleukin 1 from releasing prostaglandin in the CNA.
This stops them from elevating the hypothalamic set point for temperature control, therefore stopping a fever
Name the general pharmacokinetic properties of NSAIDS
Weak acids
Well absorbed after oral administration
Many NSAIDs have IV, IM and SC formulations too
Very high plasma protein binding - inflammation causes extravasation of proteins so NSAIDS concentrate in these areas
Where are NSAIDs biotransformed and how are they excreted
Biotransformed in the liver to inactive metabolites
Limited direct excretion via the kidney
Name the NSAID which is not metabolised but is excreted in bile
Mavacoxib
When should you NOT use NSAIDs
Animals suffering from cardiac, renal or hepatic disease
Any case with a risk of GI bleeding or ulceration
Concurrent administration of potentially nephrotoxic drugs
Name 4 common contraindications for NSAIDs
- GI disturbances
- Adverse cardiovascular effects
- Reversible renal insufficiency
- Bronchospasam
Which receptor does grapiprant target and how
It is a selective antagonist for the EP4 receptor (receptor that mediated PGE2 induced noiciception)
How is grapiprant primarily excreted
In the faeces mainly
Also directly renal excretion
