Transdermal patches types

Certain plants of the family Solanaceae, such as Atropa belladonna L., Hyoscyamus niger L., and Datura stramonium L., have been used medicinally for centuries in Europe because they contain tropane-type alkaloids.For example, atropine (1) [a racemic mixture of (+)- and (—)-hyoscyamine (2)] and (-)-hyoscyamine are competitive antagonists at the muscarinic acetylcholine receptor site, leading to antispasmodic and antiallergic effects. Scopolamine [(—)-hyoscine)] (3) is used in a transdermal patch for the prevention of motion sickness. Since these tropane alkaloids penetrate the blood-brain barrier, they also have psychoactive effects. ... 

Apparatus. The nature of the dosage form will determine the type of dissolution apparatus that will be used for method development and validation. The following questions must be asked when selecting the dissolution apparatus. Is it a capsule Will a sinker be required How stable is the drug substance after dissolution in the medium Is the formulation an immediate release or an extended release formulation Is this a transdermal patch ... 

It should be noted that at least two distinctly different types of transdermal patches or systems exist. One of these is the (liquid) reservoir system. The other is the matrix system. These systems differ both in their manufacturing steps and in their final product presentation. Key manufacturing steps for both systems are illustrated in Figure 1. 

Finally, local anesthetics can be administered via a transdermal patch.1 In particular, transdermal patches containing 5% lidocaine have been used to treat localized pain in musculoskeletal conditions (osteoarthritis, low back pain, myofascial pain)22,25,26 and various types of neuropathic pain (postherpetic neuralgia, diabetic neuropathy).2,24,58 As indicated in Chapter 2, transdermal patches provide a convenient and predictable method for administering drugs to a given anatomical site, and lidocaine patches are now being used to provide symptomatic relief in many conditions involving fairly localized pain. 

Membrane-moderated patches have been utilized in many FDA-approved transdermal patches such as Duragesic, Transderm Scop, and Catapress TTS. This type of patch utilizes a rate-controlling membrane to precisely control the release of... 

Two main types of transdermal patches are commonly used drug reservoir patch and drug-in-adhesive patch. Transdermal patches of early generations are mainly... 

Rgure 9.27 The four main types of transdermal patch matrix, reservoir, multilaminate and drug-in-adhesive designs. The matrix/reservoir systems are cut away to show the drug. Illustration courtesy of 3M. 

In 2002 a systematic review of published studies was performed to determine the effectiveness of the different forms of nicotine replacement therapy (NRT e.g., chewing gum, transdermal patches, nasal spray, inhalers, and tablets) in achieving abstinence from cigarettes or a sustained reduction in the amount smoked. The review was also designed to determine whether the effect is influenced by the clinical setting in which the smoker is recruited and treated, the dosage and form of the NRT used, or the intensity of additional advice and support offered to the smoker to determine whether combinations of NRT are more effective than one type alone and to determine its effectiveness compared to other pharmacotherapies. 

Microreservoir-type transdermal patches consist of two reservoirs, a polymeric matrix and liquid droplets of microscopic size containing the active substance. The reservoir is surrounded with a pol)nner membrane [59]. Thus multi-step diffusion takes place during the release of the active substance from the matrix into the acceptor medium (skin), from the liquid droplet into the membrane, from the membrane into the matrix. Consequently, the mathematical relationship describing this phenomenon is more comphcated than the previous ones ... 

Fractures of the spine, wrist, and hips decrease by 50 to 70%, and spinal bone density increases by 5% (24), in those women treated with estrogen within 3 years of the onset of menopause and for 5 to 1 0 years thereafter (5,11,25). The minimum dose required and that which is considered to be standard therapy is 0.625 mg/day of conjugated estrogens (Premarin) however, a 0.3 mg/day dose of esterified estrogen (Estratab) has been shown to be adequate for the prevention of osteoporosis (5). Estrogen replacement therapy is available in several types of formulations, including transdermal patches (Climera, Estraderm, Menostar, or Vivelle). 

Giingor S., Bektaj A., Alp F. I., Uydej-Dogan B. S., Ozdemir O., Araman A., Ozsoy Y. (2008). Matrix-type transdermal patches of verapamil hydrochloride In vitro permeation studies through excised rat skin and pharmacodynamic evaluation in rats. Pharm. Dev. Techno. . 13,... 

W. Pichayakom, J. Suksaeree, P. Boonme, W. Taweepreda, T. Amnuaikit, G.C. Ritthidej, Deproteinised natural rubber used as a controUing layer membrane in reservoir-type nicotine transdermal patches, Chemical Engineering Research and Design, ISSN 0263-8762 91 (3) (March 2013) 520-529. http //dx.doi.Org/10.1016/j.cherd.2012.09.011. 

---