Dermatologic Pharmacology Flashcards
___ drugs have higher distribution to the site of action, but ____ drugs have prolonged concentrations/remain longer
Hydrophilic; lipophilic
MoA of transdermal drugs
absorbed through skin, reach blood supply (reach therapeutic concentration in the plasma = goal) and then reach the site of infection -> meant to treat infection in NON-dermal regions of the body!
e.g., mirtazapine
Benefits of transdermal drug delivery
improved efficacy for time-dependent drugs; reduced toxicity (similar to CRI admin); prolonged Tmax (time to reach maximum concentration); bypasses first-pass metabolism; avoid GI effects
Ideal characteristics of transdermal drug?
- low dose required (due to prolonged Tmax)
- low MW
- lipophilic (moderately)
Rules for mirtazapine administration
- clear ear with DRY cloth
- wear gloves
- keep apart from other pets for 2 hours
- alternate ears (avoid irritation)
What transdermal drug is used for analgesia in beef cattle?
Flunixin
ID treated cattle; medication is red
What transdermal drug is used for hyperthyroidism in cats?
Methimazole (as a compounded formulation)
What type of skin infections can be treated with topical antimicrobials?
SF local or generalized conditions (SF pyoderma, otitis externa)
- ideally in glabrous skin (derm devoid of hair)
requires frequent admin (contact time)
Shampoos, ointments, otic preparations
topical
Chlorohexidine
- broad organism spectrum (bacteria, fungi, protozoa)
- cell wall destabilizer bactericidal
topical
Benzoyl Peroxide
- broad organism spectrum (bacteria, fungi)
- bactericidal (releases free oxygen radicals)
- reduces skin oils/opens pores; reduces follicular hyperkeratosis
topical & systemic
Nitrofurans
- horses
- (gram + and -) & is bactericidal (topical)
- UTIs (systemic)
- prohibited use in food animals b/c of toxicity in people!
topical
Mupirocin
- protein synthesis inhibitor
- FDA-approved for topical use in dogs
- Anti-stapylococcal acation (MRSA, MRSP use)
topical
Silver Sulfadiazine
- antifungal properties
topical
Baytil Otic
enrofloxacin + silver sulfadiazine
- syngergistic comboination (+, -, fungi)
- FDA-approved
enro = fluoroquinolone; inhibits DNA gyrase
choose ruputred ear drum +/- suspect pseudomonas
topical
Mometamax
abx + steroid + antifungal
- aminoglycosides can cause oto-toxicity! (especially if ruptured ear drum!!
amingoglycosides = gram(-)
topical
CLARO
- florfenicol + terbinafine +mometasone
- Does not treat pseudomonas; treats staphylococci
Choose over mometomax if ruptured ear drum; suspect no psuedomonas
What drug classes are case-by-case systemic antimicrobials?
3rd generation cephalosporins (cefpodoxime, cefovecin)
Systemic antifungals Terbinafine and Itraconazole: precautions & how to avoid:
drug detectable in the hair/skin weeks after the last administration -> pulse dosing for skin/hair fungal infections
autoimmune/inflammatory
Major adverse dermatologic and soft tissue effects of corticosteroid therapy:
Cushingoid appearance
Skin thinning
Alopecia
Hirsutism (horses)
Hypertrichosis
Hirsutism is the presence of an abnormally long, sometimes. abnormally structured or dense hair coat
Allergic/inflammatory
Cyclosporine
- MoA
- uses
- immunomodulator: blocks IL-2 production, inhibits calcineurin (T-cell activator)
- systemic use: atopic dermatits in dogs/cats (Atopica)
Interleukin-2 is made by a type of T lymphocyte. It increases the growth and activity of other T lymphocytes in the immune response/activation
What is cyclosporine metabolized by?
EXTENSIVLEY metabolized by liver // CYP450; p-glycoprotein efflux pump substrate
CYP450 = enzyme that metabolizes drug, predominately expressed in the liver
P-glycoprotein efflux pumps = drug clearance from cells
Describe the cyclosporine + ketaconazole synergism
Most likely does not have much long-term effects, issue b/c these treatments are usually long-term
Oclacitnib
- MoA
- common drug
- PK and PD
- kinase inhibitor (Janus-kinase = JAK-1 and -3) -> blocks signal transduction of cytokines (IL-31, IL-2, IL-4)
- Apoquel in dogs
- PK: well absorbed, distrbuted; HIGH hepatic metabolism -no CYP450 :)
- PD: controls itch within 4 hours; SID dosing
IL-31 = cytokine that triggers the process of sending itch signals to the brain
Monoclonal Antibodies (-vetmabs)
- MoA
- Use
- PK & PD
- Blocks IL-31 (monoclonal antibody against it) -> monoclonal antibodies are VERY species-specific!!
- Cytopoint (dogs) = lokivetmab
- Solensia (cats) = frunevetmab
- IV, IM, SC -> distribute within lymphatic system! -> has to hitch a ride on target cell in order to enter the tissues
IL-31 = cytokine that triggers the process of sending itch signals to the brain
Antihistamines
- precautions with first-generations
Cause BBB => drowsiness
- diphenhydramine - benadryl
Which formulation of Claritin (second-generation “antihistamine”) to use
Claritin (24-hour) - indoor and outdoor alleries (formulation without decongestant!!)
Decongestant = Claritin-D (behavioral changes, panting, tachycardia, hypertension)
