| Drug delivery technologies are now receiving | | | | components: |
| considerable attention from pharmaceutical | | | | Liner - Protects the patch during storage. The liner is |
| companies. The main purpose of developing | | | | removed prior to use. |
| alternative drug delivery technologies is to increase | | | | Drug - Drug solution in direct contact with release |
| efficiency and safety of drug delivery and provide | | | | liner |
| more convenience for the patient. Substantial | | | | Adhesive - Serves to adhere the components of |
| research conducted during the past several years has | | | | the patch together along with adhering the patch to |
| lead to the development of technologies that meet | | | | the skin |
| the requisite criteria for delivering the drug through a | | | | Membrane - Controls the release of the drug from |
| non-invasive route. One of such technologies is | | | | the reservoir and multi-layer patches |
| transdermal drug delivery.Transdermal drug delivery is | | | | Backing - Protects the patch from the outer |
| the non-invasive delivery of medications from the | | | | environment |
| surface of the skin - the largest and most accessible | | | | Types of transdermal patchesThere are four main |
| organ of the human body - through its layers, to the | | | | types of transdermal patches:Single-layer |
| circulatory system. Medication delivery is carried out | | | | Drug-in-Adhesive In this system the drug is included |
| by a patch that is attached to the body surface. | | | | directly within the skin-contacting adhesive. In this |
| Transdermal patch is a medicated adhesive pad that | | | | type of patch the adhesive layer is responsible for |
| is designed to release the active ingredient at a | | | | the releasing of the drug, and serves to adhere the |
| constant rate over a period of several hours to days | | | | various layers together, along with the entire system |
| after application to the skin. It is also called skin patch. | | | | to the skin. The adhesive layer is surrounded by a |
| A skin patch uses a special membrane to control the | | | | temporary liner and a backing.Multi-layer |
| rate at which the drug contained within the patch can | | | | Drug-in-AdhesiveThe Multi-layer Drug-in-Adhesive is |
| pass through the skin and into the bloodstream.The | | | | similar to the Single-layer Drug-in-Adhesive in that the |
| first transdermal patch was approved by the FDA in | | | | drug is incorporated directly into the adhesive. The |
| 1979. It was a patch for the treatment of motion | | | | multi-layer system adds another layer of |
| sickness. In the mid-1980s, the pharmaceutical | | | | drug-in-adhesive, usually separated by a membrane. |
| companies started the development of a nicotine | | | | This patch also has a temporary liner-layer and a |
| patch to help smokers quit smoking, and within a few | | | | permanent backing.ReservoirThe Reservoir |
| months at the end of 1991 and beginning of 1992 the | | | | transdermal system design includes a liquid |
| FDA approved four nicotine patches.Today drugs | | | | compartment containing a drug solution or suspension |
| administered through skin patches include scopolamine | | | | separated from the release liner by a semi-permeable |
| (for motion sickness), estrogen (for menopause and | | | | membrane and adhesive. The adhesive component of |
| to prevent osteoporosis after menopause), | | | | the product can either be as a continuous layer |
| nitroglycerin (for angina), lidocaine to relieve the pain | | | | between the membrane and the release liner or as a |
| of shingles (herpes zoster). Non-medicated patches | | | | concentric configuration around the membrane.Matrix |
| include thermal and cold patches, weight loss patches, | | | | The Matrix system has a drug layer of a semisolid |
| nutrient patches, skin care patches (therapeutic and | | | | matrix containing a drug solution or suspension, which |
| cosmetic), aroma patches, and patches that measure | | | | is in direct contact with the release liner. The |
| sunlight exposure.Advantages and disadvantages of | | | | adhesive layer in this patch surrounds the drug layer |
| transdermal drug delivery | | | | partially overlaying it.The future of transdermal drug |
| Transdermal drug delivery systems offer several | | | | deliveryTransdermal drug delivery is theoretically ideal |
| important advantages over more traditional | | | | for many injected and orally delivered drugs, but |
| approaches, including: | | | | many drugs cannot pass through the skin because of |
| | | | skin's low permeability. Pharmaceutical companies |
| longer duration of action resulting in a reduction in | | | | develop new adhesives, molecular absorption |
| dosing frequency | | | | enhancers, and penetration enhancers that will |
| Increased convenience to administer drugs which | | | | enhance skin permeability and thus greatly expand |
| would otherwise require frequent dosing | | | | the range of drugs that can be delivered |
| improved bioavailability | | | | transdermally.Two of the better-known technologies |
| more uniform plasma levels | | | | that can help achieve significant skin permeation |
| reduced side effects and improved therapy due to | | | | enhancement are iontophoresis and phonophoresis |
| maintenance of plasma levels up to the end of the | | | | (sonophoresis). Iontophoresis involves passing a direct |
| dosing interval | | | | electrical current between two electrodes on the skin |
| flexibility of terminating the drug administration by | | | | surface. Phonophoresis uses ultrasonic frequencies to |
| simply removing the patch from the skin | | | | help transfer high molecular weight drugs through the |
| Improved patient compliance and comfort via | | | | skin.A newer and potentially more promising |
| non-invasive, painless and simple application | | | | technology is micro needle-enhanced delivery. These |
| Some of the greatest disadvantages to transdermal | | | | systems use an array of tiny needle-like structures |
| drug delivery are: | | | | to open pores in the stratum corneum and facilitate |
| possibility that a local irritation at the site of | | | | drug transport. The structures are small enough that |
| application | | | | they do not reach the nerve endings, so there is no |
| Erythema, itching, and local edema can be caused by | | | | sensation of pain. These systems have been |
| the drug, the adhesive, or other excipients in the | | | | reported to greatly enhance (up to 100,000 fold) the |
| patch formulation | | | | permeation of macromolecules through skin.Yury |
| The main components of a transdermal patch are: | | | | Bayarski is the author of - website, offering patches |
| Transdermal patch may include the following | | | | and natural health products. |