Transdermal drug delivery

What are the advantages of transdermal drug delivery?

-bypass first pass effect

-reduce side effects by controlled release

-reduce inter and intra-patient variability

-increase pt compliance with fewer dosing events

-self-administration

-easy to apply and remove

What are the disadvantages of transdermal drug delivery?

-lipophilic drugs with low MW

-potent drugs only

-drugs with short half-lives

-irritation at application site

-erythema

-itching

-edema

-lag time to reach ss

-skin damage

What are the steps in transdermal drug delivery?

drug reservior passes through adhesive film then stratum corneum into epidermis then dermis then into blood circulation by capillaries

How does oleic acid act as a penetration enhancer?

inserts into lipid increasing space because of cis structure, allows drug passage

What does the systemic effect of transdermal delivery model?

infusion like drug absorption due to overfilled drug reservoir

What are the components of a transdermal delivery device?

-backing layer

-rate-controlling matrix or membrane

-adhesive layer

-others

What are characteristics of the backing layer?

-must be impermeable to drug and enhancer

-usually impermeable to water vapor

What are characteristics of the adhesive layer?

-non-irritating

-non-toxic

-low drug affinity except for drug-in-adhesive patches

What are other device components?

-peel strip

-packet

What is apart of the reservoir controlled system?

-backing

-drug containing reservoir

-rate controlling membrane

-adhesive

What is apart of the matrix controlled system?

-backing

-rate-controlling maxtrix containing drug

-adhesive

What equation describes transdermal drug absorption?

dM/dt = (D*K*A*delta C)/h

What sites can you rotate the birth control patch to minimize irritation?

-abdomen

-buttocks

-shoulder

-upper arm

What is the patient counseling for transdermal drug systems?

-most patches should not be cut

-area of application: clean, dry, non-hair area

-site rotation

-apply firmly

-removal of old patch

-excess drug in patches

-disposal methods

-avoid high heat

What does heat or exercise do to the rate at which drug is absorbed?

increase rate

What are the pathways of transdermal drug delivery?

-diffusion

-iontophoresis: low electrical current

-electroporation: high-voltage pulses

-microneedles

What is iontophoresis?

charge repulsion that drives drug and RNA across skin

What are the advantages of oral route?

-avoid pain

-easy to swallow and convenient

-various dosage forms

-self-administration

-high patient compliance

What are the disadvantages to oral delivery?

-enzymatic degradation

-acidic environment in GIT

-longer absorption process

-plasma level slowly achieved

-first pass metabolism

what are the advantages to transdermal drug delivery?

-not or less invasive

-ease on application

-self-administration

-avoid first pass

-various dosage forms and methods

-reduce frequency of admin

What are the advantages of intravenous injection?

-100% bioavailability

-plasma level can be achieved quickly

-avoid hepatic metabolism

-used in emergency condition

-accurate dose

What are the disadvantages of intravenous injection?

-invasive

-painful

-expert personnel needed

-no self-administration

-needles waste disposal problems