Transdermal use

Polymer coatings responsive to temperature or moisture form the basis for medications delivered transdermally using patches on the skin or internally via inserts implanted in the body. Oral nitroglycerin (Fig. 14.1.4) tablets to prevent... 

Fentanyl transdermal patches are intended for transdermal use (on intact skin) only. Using damaged or cut fentanyl transdermal patches can lead to the rapid release of the contents of the fentanyl transdermal patch and absorption of a potentially fatal dose of fentanyl. 

V.a.1.2. Transdermal preparations. Adhesive patches applied to the skin can be used to deliver oestrogens transdermally, using either a reservoir of liquid or an oestradiol-containing matrix. These systems deliver adequate amounts of oestradiol to maintain plasma levels within the normal range for 24 hours, and some preparations now provide transdermal progestagen also, thus avoiding the need for additional tablets to be taken for part of the cycle. 

Physical therapists may encounter the use of local anesthetics in several patient situations because of their various clinical applications. For example, therapists may be directly involved in the topical or transdermal administration of local anesthetics. As discussed earlier, repeated topical application of local anesthetics may help produce long-term improvements in motor function in patients with skeletal muscle hypertonicity, so therapists may want to consider incorporating topical anesthetics into the treatment of certain patients with CNS dysfunction. Therapists may also administer local anesthetics transdermally, using the techniques of iontophoresis and phonophoresis. Agents such as lido-caine can be administered through this method for the treatment of acute inflammation in bursitis, tendinitis, and so on. 

To deliver a therapeutically-effective dose transdermally using a TDD system with a reasonable size (e.g., < 20 cm ), the barrier properties of the skin for drug permeation must be overcome to effectively deliver the drugs transdermally at a controlled rate. The following approaches have been shown to potentially decrease the skin s barrier properties and enhance the transdermal permeation of the drugs (ji) ... 

Rao PR, Diwan PV. Permeability studies of cellulose acetate free films for transdermal use influences of plasticizers. Pharm Acta Helv 1997 72 47-51. 

Hormones, proteins, and small peptides are not suitable for oral administration without complex modifications in the formulation. A variety of approaches for insulin delivery, as a model drug, have been attempted to improve on its bioavailability. Advances have been realized in the delivery of insulin through oral, nasal, rectal, dermatologic, and ocular routes. Proteins can also be delivered transdermally, using a lipid-based, biphasic delivery system in therapeutic quantity. 

Proteins can also be delivered transdermally using a lipid-based biphasic delivery system in therapeutic quantity. Insulin treatment (10-50 mg/g formulation) was administered by a transdermal patch adhered to the abdomen of anesthetized Sprague-Dawley rats made diabetic by a single injection of strep-tozotocin (55 mg/kg). Blood was sampled from a tail vein every 2-4 h for 48 h. Response to transdermally applied insulin was both pH and concentration dependent. Blood glucose was decreased by 55% in the treated animals with mean response duration of 15 h. Serum insulin level was 162 pg/mL. 

Amnuaikit C, Dceuchi I, Ogawara K, Higaki K, Kimura T (2005) Skin permeation of propranolol from polymeric film containing terpene enhancers for transdermal use. Int J Pharm 289 167-178... 

Fentanyl transdermal system is intended for transdermal use only. Doses should be individualized and calculated based on the PO, IM, or IV opioid requirements (see below, as pubhshed by the manufacturer). Available patch dosages are 12.5,25,50, 75, and 100 pg per hour. The 25 pg/h FTS patches were recalled in February2008 due to a concern that small cuts in the gel reservoir could result in accidental exposure to fentan)d [1]. 

Fig. 45. Schematic of transdermal patch in which the rate of deUvery of dmg to the body is controlled by a polymer membrane. Such patches are used to...

Passive transdermal dehvery systems on the market tend to be either matrix or membrane controUed. In matrix devices, the stmctural and molecular characteristics of the dmg-polymer matrix determine dmg release. Examples of polymer matrix-controUed diffusional systems for angina prophylaxis include Nitro-Dur and Nitrodisc, which provide transdermal dehvery of nitroglycerin [55-63-0], and Erandol, a tape that releases isosorbide dinitrate [87-33-2]. Matrix diffusional systems have been used for dehvering dmgs with a wide therapeutic index. 

These include atropine, scopolamine (hyoscine), trihexyphenidyl (benzhexol) and benzatropine. They block central muscarinic receptors involved in various afferent pathways of the vomiting reflex (Fig. 1). They have been used to control motion sickness, emesis in Meniere s disease and postoperative vomiting. Currently, hyoscine is largely restricted to the treatment of motion sickness where it has a fast onset of action but a short duration (4-6 h). Administration of hyoscine by transdermal patch produces a prolonged, low-level release of the drug with minimal side effects. To control postoperative vomiting, it should be applied >8 h before emesis is anticipated. 

Dru may be applied to the skin and mucous membranes using several routes topically (on the outer layers of skin), transdermally through a patch on which the drug has been implanted, or inhaled through the membranes of the upper respiratory tract. 

Rotate sites for transdermal patches to prevent skin irritation. The chest, flank, and upper arm are die most commonly used sites. Do not shave die area to apply die patch shaving may cause skin irritation. 

The use of the transdermal route in the elderly is questionable because the amount of subcutaneous tissue is reduced in the aging process... 

The nitrates are available in various forms (eg, sublingual, transmucosal, translingual spray, and inhalation). Some adverse reactions are a result of the metiiod of administration. For example, sublingual nitroglycerin may cause a local burning or tingling in the oral cavity. However, die patient must be aware that an absence of this effect does not indicate a decrease in the drug s potency. Contact dermatitis may occur from use of die transdermal delivery system. 

When using the topical ointment form or transder-mal system, cleanse old application sites witii soap and warm water as soon as the ointment or transdermal system is removed. 

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