Dermatologic Pharmacology Flashcards
Drugs used in the treatment of the skin can be
delivered systemically
applied topically
injected directly to the dermis
phototherapy
pharmacologic responses are determined by:
- Regional variation in drug penetration
- Concentration Gradient
- Dosing schedule
- Vehicles & Occluion
- State of Stratum Corneum
- Presence of Penetration Enhancers
which part easily absorbs drug:
face, scrotum, axilla scalp vs soles of foot
face, scrotum, axilla, scalp
increase in conc gradient increases the
mass of drug transferred per unit time
may be long enough to permit
once daily application with short systemic half-lives
local half life
Topical absorption increased in dermatologic
disorders due to
presence of breaks/ lesions in the skin
these are added for better drug penetration
penetration enhancers
examples of penetration enhancers
Org solvents such as dimethyl sulfoxide urea, and salicylic acid
drug absorption i influenced by
- conc of drug in the vehicle
- The partition coefficient of drug between the
stratum corneum and the vehicle - Diffusion coefficient of the drug in the stratum
corneum
Rate of diffusion is proportional to
concentration
drug’s ability to escape
from the vehicle.
partition coefficient
Increased lipid-solubility favors penetration through
the skin in
relatively lipophilic stratum corneum
refers to the extent to which the matrix of the barrier
restricts the mobility of the drug
Diffusion coefficient
Increase in the molecular size of the drug will
decrease the diffusion coefficient.
any of various media acting usually as
solvents, carriers, or binders for active ingredients.
vehicle
Acute inflammation with oozing, vesiculation &
crusting are best treated with
drying preparations (e.g. tinctures, wet dressings, lotions)
Chronic Inflammation with xerosis, scaling &
lichenification are best treated with
more lubricating preparations (e.g.
Creams or Ointments)
Most effective hydrating agents
ointment
Most acceptable, accessible, and common
preparation
cream
Amount of ointment when squeezed out of a tube to the
palmar aspect of the index finger from the distal skin
crease to the end of the finger
FTU - fingertip unit
Known as steroids in laymen’s term
glucocorticoid
therapeutic effectiveness of topical glucocorticoids is based on
based on their anti-inflammatory activity
inhibition of accumulation of Neutrophils and monocytes at the site of inflammation would lead to
decreased proliferation and migration of lymphocytes and macrophages
Steroid to be used are chosen on the basis of
potency, ite of involvement and severity
T or F: application of steroid more than twice a day increases it efficacy
F more frequent application doen’t improve response due to half life
All absorbable topical corticosteroids possess the
potential to
suppress the pituitary adrenal axis
use of steroids in children would result to
early closure of long bones/ growth retardation
Intralesional glucocorticoids can cause
cutaneous atrophy and hypopigmentation
Reserve for acute treatment of transient illnesses or lifethreatening
dermatoses
systemic glucocorticoids
why do you need to gradually decrease the dosing schedule of glucocorticoids
for less adverse effect for withdrawal and to prevent adrenal crisis
Used mainly for the treatment of psoriasis, dermatitis &
lichen simplex chronicus
tar compounds
main cause of the discontinuation of
certain drug practices
sensitization
why you should not advocate the use of topical antibacterial agent
exposure of the individual to the possibility of sensitization
mode of action of bacitracin and B. Gramicidin
inhibits cell wall synthesis
side effects of bacitracin
contact urticaria
anaphylaxis
systemic toxicity
contact dermatitis
why is neomycin used in surgery
because it is an aminoglycoside and they are not aborbed in GI tract; they stay to disinfect the area
Used to treat Impetigo contagiosa specifically
mupirocin
New synthetic drug, newer than mupirocin
retapamulin
retapamulin is effective in treatment of
uncomplicated superficial
skin infection caused by Grp. A beta-hemolytic strep
and S. aureus excluding MRSA for adult and pediatric
patients 9 months and older
Peptide antibody effective against Gram (-) organism
including P. Aeruginosa, E. Coli, Enterobacter &
Klebsiella
polymyxin B sulfate
why should you not exceed 200mg of Polymyxin B sulfate when applied to denuded skin
Causes neurotoxicity and nephrotoxicity
MOA of Neomycin
inhibits CHON synthesis
Adverse effects of aminoglycosides in general
neurotoxicity, nephrotoxicity and ototoxicity,
neuromuscular blockage
What is cross sensitivity
means that even if an individual has
not been exposed to these drugs, he may still
develop allergies to other related drugs
generally, aminoglycosides are for
Gm (-)
clindamycin may cause rare cases of ___ when aborbed systemically
bloody diarrhea & pseudomembranous colitis
clindamycin is known commercially as
Dalacin C
effect of erythromycin
inhibotry on P. acnes
side effect of erythromycin
burning drying irritation
drug for amoebiasis
metronidazole
Topical Gel effective in acne rosacea
metronidazole
MOA of metronidazole
UNKNOWN but may relate to the inhibitory effects
on Demodex brevis (face mite)
MOA of sodium sulfacetamide
Inhibition of P. Acnes by competitive inhibition of
PABA utilization
sodium sulfacetamide is contraindicated in patients that are
sensitive to sulfonamides
action of Retinoic acid in acne
decreased cohesion
between epidermal cells and increased epidermal cell
turnover which results in expulsion of open comedones
For severe cystic acne
isotretinoin
MOA of isotretinoin
inhibit sebaceous gland size & function
Still a Vitamin A/retinoid;
Treatment of psoriasis especially pustular forms
etretinate
MOA of doxepin
H1 & H2 antagonists property percutaneous
absorption
why does doxepin cause urinary retention
anticholinergic effects
For itchiness, we administer
anesthetics or antihistaminics
why older h1 receptor antagonists sedating?
they can cross blood brain barrier
difference of newer H1 receptor antagonists from the old ones
they do not cross the BBB and they don’t cause drowiness/ sedation
why H2 receptor blockers are better used for patients with peptic ulcer
Decreases gastric acid secretion;
Inhibit HCl production
