Pharm For Skin 1 Flashcards
Principles for topical therapy
Drug is applied directly to site of action to exert effect
Common locations are skin, ear, joint/local areas
Principles of systemic admin
Drugs are administered externally to be absorbed and have affect at site of action - dermis, subQ etc
Therapeutic concentrations in plasma are important/required
Systemic drugs and skin
Site of action is extracellular fluid or interstitial fluid
Protein binding limits movement
Hydrophilic & lipophilic can reach site of action
Transdermal drugs
Drugs applied locally at site
Absorbed systemically to have effect at site of action
Help improve patient compliance, decreases dosing freq/cost, good for hard to pill animals
Transdermal drug delivery
Improved efficacy for time dependent drugs
Reduced tox with lower peaks (CRI)
Prolonged Tmax
Bypass first pass metabolism
Avoids GI side effects
Pros and cons fo transdermal drug delivery
Pros:
Low dose required
Low molecular weight
Moderately lipophilic
Cons:
Hair
Skin thickness variations - site of application
Names of transdermal drugs
Mirtazapine
Flunixin
Flea/tick products
Methimazole (compounded)
Fentanyl patch
Mirtazapine
Can cause weight loss in acts
Clean ear w dry cloth, wear gloves, DO NOT pet or allow near animals for 2 hours
Alternate ears - to prevent irritation
Flunixin
Common in beef cattle
Analgesia
RED - ID treated animals
Compounded formulations for transdermal drugs
Maintain healthy skepticism
NOT appropriate for treating systemic infection
Research backed
Topical antimicrobials
Good for superficial or generalized conditions
Require frequent admin - ^^ contact time
Can delay healing
Types of high concentration topical Antimicrobials
High concentrations @site directly
C/S can underestimate activity
Includes shampoos, ointment, otic preparations
Common formulations for topical antimicrobials
Chlorhexidine
Benzoyl peroxide
Nitrofurans
Mupirocin
Silver sulfadiazine
Otic
- antibiotic + antifungal + anti inflammatory
- otitis externa
Chlorhexidine
Broad spectrum - good against bacteria, fungi, Protozoa
Cell wall destabilizer = cidal
Ointment, intrauterine suspension, bolus (LA)
Shampoos, sprays, wipes
Benzoyl peroxide
Broad spectrum - bacteria, fungi
Reduces skin oil/open pores
- anti inflammatory & degreaser
Release free oxygen radical - bacterial CIDAL
Reduces follicular HK
Comes in shampoos
Nitrofurans
Block oxidative reactions in formations of bacteria acetyl coenzyme A
CIDAL @ high concentrations
- topical
-systemic - UTI
Spectrum of action of Nitrofurans
UTI
Gram positive & negative - staph, E. Coli
Tox of Nitrofurans
Hypersensitivity in people
Possible mutagen and carcinogen in people
PROHIBITED in Food animals - both systemic & topical
Mupirocin
Protein synthesis inhibitors
Prevents incorporation of isoleucine into proteins
^ unique mechanisms of other antibacterials
Active spectrum of mupirocin
Active against aerobic Gram-positive organisms, some Gram negative
ANTI staph (MRSA, MRSP) action
FDA approved for topical use in dogs
Silver sulfadiazine
Silver component interferes with cell wall
- antifungal properties
Sulfadiazine - folic acid pathway
Used to treat burns in humans
Enrofloxacin + silver sulfadiazine
Synergistic combo therapy
- gram positive
- gram negative
- fungus
FDA approved for dogs - baytril otic
Topical Antimicrobials against otic
Enrofloxacin + silver sulfadiazine
Gentamicin + mometasone + clotrimazole
Florfenicol + Terbinafine + mometasone
Amphenicol
Orbifloxicin + mometasone + posaconazole
Gentamicin + mometasone + clotrimazole
Aminoglycosides - gram neg aerobes, staph
Steroids
Azole antifungal - action against malassezia
Increases risk for ototoxicity - esp if ear drums ruptured
Florfenicol + Terbinafine + mometasone
Amphenicol - similar to chloramphenicol but no aplastic anemia
Broad spectrum action - staph but not pseudomonas
Allylamine antifungal
Steroid
Orbifloxicin + mometasone + posaconasole
Systemic antimicrobials
Good for deep conditions
Widespread conditions - deep pyoderma, otitis externa
Can use w combo therapy
Drugs of systemic antimicrobials
Beta lactams
- cephalexin, cefadroxil
- amoxicillin - clavulanate
Lincosamides
Potentiated sulfonamides
Beta lactam antibiotics
Cephalexin, ceradroxil
- first generation cephalosporins
Amoxicillian-clavulanate: beta lactam/lactamase inhibitor
Lincosamides
Clindamycin
Potentiated sulfonamides
Tirmethoprim-sulfa
Concerns over toxicity
Using systemic antimicrobials
1st or 2nd tier treatment
Case-by-case basis
3rd gen cephalosporins - cefpodoxime
2nd/3rd tier - culture based
Fungal therapies
Combo of topical and systemic
Fungus commonly accumulates in hair /skin
- griseofulvin - ring worm
- Terbinafine
- itraconazole
Terbinafine
Admin 30-40mg/kg PO q24 for 14 days
Results will be detectable in hair for additional 8 weeks
Itraconazole
Concentrations settle in the sebaceous glands, 5-10x plasma concentrations
Detected in surface skin 3-4 weeks after XX therapy
Unique PK of systemic antimicrobials
Drugs class - imidazole
Drugs:
Miconazole - conofite cream
Clotrimazole - lotrimin topical, mometamax or otomax
Drug class- polyene
Drugs:
Nystatin: mycostatin
Drug class - allylamine
Drugs :
Terbinafine - osurina & Claro (et al)
