Transdermal and Dermal Patches Flashcards
What are advantages of transdermal drug delivery?
Avoids GI drug absorption difficulties Alternative to oral and parenteral avoids first-pass metabolism multi-day therapy with one application extends activity of drugs with short half-lives easy to terminate drug's effects
What are disadvantages of transdermal drug delivery?
Unsuitable for drugs that sensitize skin
Only relatively potent drugs can be used
Adhesion of the transdermal delivery system may be variable
What are the main pharmacokinetic advantages of transdermal delivery?
sustained delivery over a long period of time
keeps drug levels within MEC and MTC
avoids first pass effect
What kinds of drugs are good candidates for transdermal delivery?
High potency drugs Short half-life Low molecular weight Lipophilic drugs Low melting point High skin permeability Non-irritating and non-sensitizing to skin Low oral bioavailability Low therapeutic index
What are requirements for transdermal patches?
Shelf life up to 2 years
Small patch size
No residue
Cosmetically appealing and easy to use
What types of transdermal patches are there and what are their properties?
Reservoir type: has a rate controlling membrane
Matrix type: drug in matrix
Drug in adhesive: monolithic or multilaminate
What are the components of a transdermal patch?
Backing film, rate-controlling membrane, drug matrix or vehicle, pressure sensitive adhesives, release liners
What are the advantages of drug in adhesive patches with regards to dosing, comfort and control of delivery?
Comfortable, thin patch
Maximum use of the surface area of the patch
Can be cut to adjust dose
What are the main safety issues with patches?
Confusion- patch designs, dose strengths, frequency
Improper application
Nomenclature issues- mg/h, mg/day
Dosing intervals
Physician errors
Pediatric patch issues- cutting isn’t possible with reservoir patches
Safe storage
Rules and instructions of patch application?
Apply on non-hairy areas
Site of application should be dry
Do not apply to areas with cuts or damage
Do not apply below knee or elbow
What type of fentanyl TTS are available and what is the importance from a safety POV?
All 3 patch designs are available
Reservoir patches can puncture and dose dumping can occur– leads to overdose
What is the rationale for using DTS?
Maximize delivery into stratum corneum, upper epidermis or dermis while minimizing systemic circulation
Used for local dermatological conditions
