Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Wearing apparel – fabric – or cloth
Reexamination Certificate
2000-02-22
2001-11-20
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Wearing apparel, fabric, or cloth
C424S402000, C424S443000, C424S449000, C424S448000, C424S426000
Reexamination Certificate
active
06319510
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to an improved methods for treatment of systemic diseases and illnesses by delivery of medication into the body through oral mucosal tissue. More particularly, it concerns the use of a layered pad (Gum Pad) which is worn intra-orally on the gums for dispensing medication contained in the pad by saliva diffusion and transport to the oral mucosal tissues.
BACKGROUND
It is known that medication can be absorbed into the body through the soft mucosal tissues in the interior layers of the body. The medication can pass through the tissues directly into the systemic circulation, bypassing breakdown by digestive enzymes in the stomach and preventing the medication from passing through the liver where it can be degraded or eliminated. Many medications, especially proteins and peptides, are rendered useless by the gut and liver. Transmucosal delivery preserves the potency of these medications. The efficacy of transmucosal delivery depends in large part on the extent of the mucosal surface exposed to medication and the time over which the medication remains present and available on the mucosal surface.
Many medications that are administered parenterally (by injection), can also be given transmucosally. Transmucosal delivery is preferable in that close medical supervision is not required and it is not associated with scar formation, infection, and noncompliance. However, transmucosal administration is less efficient than parenteral (injectable) medication with a smaller percentage of medication entering the systemic circulation. Therefore, transmucosal administration may require a higher concentration of medication or a longer duration of administration than parenteral. Parenteral administration can produce an effect more rapidly and in a more controlled manner. However, some medications can produce unexpected, toxic effects. If toxic effects are noted shortly after parenteral injection, increasing toxicity is inevitable as the medication cannot be withdrawn. Transmucosal delivery is safer in that the medication can quickly and easily be withdrawn when signs of toxicity are noted.
Transmucosal delivery is especially suitable for pre-operative patients who must have an empty stomach; cancer patients undergoing chemotherapy or radiotherapy who are nauseated; patients who fear needles; patients with skin conditions; and children who resist swallowing or who are afraid of injections.
Transmucosal delivery forms and devices are known to the art. Medication can be delivered transmucosally through lungs, mouth, nose, vagina, conjunctiva, rectum, bladder, and urethra. Pulmonary mucosa demonstrate the highest absorption rate due to the extensive surface area of the alveolae. After pulmonary mucosa, nasal and buccal mucosa are the most penetrable, followed by rectal, and vaginal, in that order.
Oral mucosal delivery offers several distinct advantages over other routes. The mouth is easily accessible with a wide aperture and a broad mucosal surface. The medication can pass easily into the reticulated veins that lie under the oral mucosa. The oral mucosa has more lipophillic cells than other mucosae, allowing for the delivery of lipophillic medications. Medication is more easily absorbed through the oral mucosa than through skin or rectal mucosa. Medication placed in the mouth is more acceptable to patients and more easily controlled than medication placed in the rectum, urethra, vagina, bladder, or up the nose. Problems associated with oral transmucosal delivery include medication's noxious taste or irritation and the fact that a large amount of saliva (up to 2 liters per day) is produced by salivary glands in the mouth. Too much saliva can dilute and carry away medication.
Absorption rates across mucosal surfaces vary according to the physicochemical properties of the mucosa such as thickness of the epithelial layers, electrical resistance, and hydrophilic or lipophilic characteristics. Oral mucosa are generally lipophilic in nature so that molecules that are more lipophilic will penetrate more rapidly. Absorption through the mucosa is influenced by molecular size, concentration, ionization, and pH of the medication. Small, lipid-soluble molecules pass easily through the oral mucosa. Absorption is affected by the presence of various enzymes in the saliva, rate of saliva flow, viscosity, pH, and electrical resistance. It is found that medication absorbed through the buccal mucosa enters the circulation 4 to 8 times more rapidly than when it is ingested in pill or capsule form. Effects can be observed in 5-20 minutes compared to 30-60 minutes by ingestion into the stomach. Oral transmucosal delivery is also 20-30 times faster than transdermal (skin patch) delivery.
Oral Transmucosal Delivery Devices
Oral transmucosal delivery forms and devices are known to the art. U.S. Pat. No. 3,510,053, to Focke, U.S. Pat. No. 5,197,882 to Jemberg, U.S. Pat. No. 5,267,862 to Parker and U.S. Pat. No. 5,326,685 to Gaglio et al. are illustrative of such prior art. The Gaglio patent is of interest as it discloses an oral pad device having a hollow pocket formed by a flexible backing material and a porous outer layer for holding a viscous medication in gel, salve or liquid form. The viscous medication can pass through the porous layer onto the surfaces desired to be treated, such as the gums for treatment of gum diseases or onto the teeth for teeth whitening. The rate of delivery depends entirely on the porosity of the flexible outer layer.
Buccal and sublingual tablets as well as lozenges have been used for transmucosal delivery of medication. Medication has also been mixed with syrup and fruit-flavored gels, compressed into a sustained release buccal tablets, and incorporated into a lozenge mounted on a handle (Oralet). Measured sprays have recently been developed for sub-lingual use. When medication is delivered by these methods, it is rapidly dispersed by saliva, does not remain in contact with the mucosa, and is often rendered ineffective when swallowed.. Saliva secretion is stimulated by flavoring agents commonly employed and this furthers the dispersion and removal of the medication. When medication is swallowed it may adversely affect the digestive system. Children, especially, find it difficult not to swallow tablets, lozenges, syrup, and fruit-flavored gels.
Compressed tablets including bi-layered and multi-layered products that deliver an active ingredient after being inserted between the gingiva and buccal mucosa are known in the art. Ebert et al., U.S. Pat. No. 5,849,322, discloses a bi-layered tablet comprised of medication in one layer and adhesive in the other. The adhesive layer attaches to the gingiva and the drug-containing layer is in drug transfer contact with the buccal mucosa. Davis et al., U.S. Pat. No. 4,540,566, discloses a compressed tablet comprising cellulose ether. Schor et al., U.S. Pat. No. 4,389,393, describes a compressed tablet comprised of hydroxypropylmethylcellulose, or a mixture of methylcellulose and sodium carboxylmethylcellulose, and/or other cellulose ethers. These tablets are subject to being chewed or swallowed, in which case the active ingredients may be destroyed by digestive enzymes. Even when retained between the gingiva and buccal mucosa, tablets usually dissolve in less than an hour, making them unsuitable for medications that require a longer release time. When tablets are constructed to adhere to the buccal mucosa with adhesive, significant irritation can be caused by the adhesive and the direct contact between concentrated medication and a limited area of mucosa. If tablets are dislodged, they can be chewed and fractured or swallowed.
Osmotic dosage forms for sustained delivery of medications to various treatment sites including oral mucosa are disclosed in U.S. Pat. No. 5,021,053 to Barclay et al., U.S. Pat. No. 5,248,310 to Barclay et al., U.S. Pat. No. 5,200,194 to Edgren et al., and U.S. Pat. No. 5,200,195 to Dong et al., all of which are incorporated by reference herein. These devices are formed as ta
Chong Leighton K.
Ghali Isis
Page Thurman K.
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