Transdermal patches advantages

Clonidine is also available as a transdermal patch (Catapres-TTS [transdermal therapeutic system]) that has the advantages of avoiding the need for repeated doses during the day and of reportedly lower rates of dry mouth and drowsiness (Burris, 1993). Steady-state plasma levels are reached within 2-3 days after applying the patch and clonidine concentrations reportedly diminish gradually over 2-3 days following patch removal, without rebound hypertension in adult hyper-... 

Transdermal patches are an alternative for patients that are not able to take oral medication. Advantages of transdermal patches are that they are easily applied and may prevent more painful and arduous parenteral administration. Moreover, transdermal administration is advantageous for active substances that undergo extensive first-pass metabolism, active substances with narrow therapeutic window or active substances with a short half-life, which cause noncompliance due to frequent dosing. 

Therapeutically used types of estrogens and prog-estins are listed in Tables 30-4 and 30-5. Both types of hormones can be administered in their natural form (estradiol and progesterone), and several synthetic derivatives of each type are also available. Most of the drugs listed in Tables 30-4 and 30-5 are available as oral preparations, and many conditions can be conveniently treated by oral administration. These hormones may also be administered transdermally via patches, creams, or gels the transdermal route may offer certain advantages, such as decreased side effects and liver problems.86,130 Certain preparations can be... 

In contrast to hyoscyamine/atropine which shows central depressant as well as central excitatory properties, its congener scopolamine is only characterized by the former property. Thus, it is suitable as a prophylactic antiemetic applied by a certain patch before a surgery or a travel in order to avoid nausea. An advantage of such a so-called transdermal delivery system (TDS) is given in so far as a steady blood level for three days is produced which is high enough to act as an antiemetic but low enough to be free from severe side effects (Tolksdorf et al. 1985). 

The main advantages of transdermal over oral drug delivery are the ability to maintain constant plasma levels with short-half-life dmgs and to avoid the hostile conditions of the gastrointestinal tract and consequent drug deactivation because of the hepatic first-pass effect. Moreover, patient compliance tends to increase, reducing the number of administrations required. Patches are now available for once-a-day, twice-a-week, and once-a-week treatment. 

The capacity of the skin to absorb lipid-soluble chemicals is both a blessing and a curse. Transdermal medicated adhesive patches, for example, take advantage of the capacity of the skin to absorb small lipophilic compounds in order to administer chemicals such as scopolamine, the anti-sea sickness drug, and nicotine. Unfortunately, urushiol, the active ingredient found in poison ivy, poison oak, and poison sumac, also takes advantage of the skin s capacity to absorb small, lipophilic chemicals, and is absorbed via the dermal pathway. 

Patches based on GL and pectin hydrogels were described by Mazzitelli et al. (2013). Hydrogels are formed by taking advantage of the different gelling properties of pectin and gelatin (i.e., ionic and thermal gelation mechanisms), and proposed as transdermal formulations for the delivery of testosterone to overcome the limitation of its low bioavailability due to liver pre-systemic metabolism. 

---