255 Nicotine Nitroglycerin

L-Aspartyl-L-Phenylalanine Methyl Ester Luminol Menthol Methane Methyl Alcohol Methyl Mercaptan Methyl-t-butyl Ether Monosodium Glutamate N,N-Diethyl-3-Methyl-benzamide Naphthalene Naproxen Niacin Nicotine Nitroglycerin Nylon 6 and Nylon 66 Oxalic Acid Pectin Penicillin Petrolatum Petroleum Phenol... 

Active substances used in membrane diffusion transdermal systems can be the following steroid hormones, clonidine, scopolamine, nicotine, nitroglycerine, dexamethasone, propranolol, and analgesics (e.g. phentanyl, buprenor-phine), [60, 61, 75]. 

Oral mucosal membranes provide a port for systemic therapy as weU. Nitroglycerin sublingual tablets (Nitrostat) abort acute mgina attacks methyl-testosterone [58-18-4] buccal tablets (Android 5) are indicated for testosterone [58-22-0] replacement therapy (39) md nicotine [54-11-5] gum (Nicorette) aids in smoking cessation. 

Despite the limitations imposed by the physiology of the skin, several marketed controUed release transdermal dmg dehvery systems are available in the United States for example, scopolamine [51-34-3] for the treatment of motion sickness, nitroglycerin [55-63-0] for angina, estradiol [50-28-2] for the rehef of postmenopausal symptoms and osteoporosis, clonidine [4205-90-7] for the treatment of hypertension, fentanyl [437-38-7] as an analgesic, and nicotine [54-11-5] as an aid to smoking cessation. These systems are designed to dehver dmg for periods of one to seven days. 

Transdermal patches are applied to the skin. The drug is mixed with the adhesive for the patch, and so it lies next to the skin. The skin can readily absorb many chemicals and so can absorb drugs such as nitroglycerin (for heart disease), morphine derivatives (for constant, severe pain), estrogen (for hormone replacement therapy), or nicotine (for easing symptoms that result when a patient stops smoking). 

Transdermal products with semisolid matrix design include Habitrol, Nitrodisc, Nitroglycerin Transdermal, and Prostep. For example, Habitrol consists of an impermeable backing laminate with a layer of adhesive and a nonwoven pad to which a nicotine solution is applied. Multiple layers of adhesive on a release liner are then laminated on the patch. The systems come in 10-, 20-, and 30-cm2 sizes corresponding to 7, 14, and 21 mg/day, respectively, delivered over 24 hours. 

Figure 1.8 Schematic of transdermal patch in which the rate of delivery of drug to the body is controlled by a polymer membrane. Such patches are used to deliver many drugs including nitroglycerine, estradiol, nicotine and scopalamine...

Equation (4.4) shows that the melting point is an important determinant in solubility calculations, the lower the melting point, the lower the inter-molecular forces, and therefore the easier it is for the drug to dissolve in the intercellular lipids of the skin. It is interesting to note that two of the successful transdermally delivered drugs, nitroglycerin and nicotine, are low melting point materials. 

Advances in transdermal delivery systems (TDSs) and the technology involved have been rapid because of the sophistication of polymer science, which now allows incorporation of polymeric additives in TDSs in adequate quantity. Drugs with which transdermal therapy was pioneered include scopolamine, nitroglycerine, iso-sorbide dinitrite, clonidine, estradiol, nicotine, and testosterone [74],... 

Transdermal administration can avoid first-pass metabolism as well as provide a large surface area for continuous-controlled administration of drugs with short biological half-lives and narrow therapeutical indices. The route has been used for nitroglycerin ointments, and transdermal therapeutical systems (patches) have been developed for scopolamine, nitroglycerin, clonidine, estradiol, and nicotine. 

With this route a drug tablet is placed under the tongue and dissolves in saliva. The drug is absorbed through the mouth s mucous membranes. Nitroglycerin, which is taken for treatment of angina pectoris (heart pain), usually is taken sublingually. Nicotine... 

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