Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Web – sheet or filament bases; compositions of bandages; or...
Reexamination Certificate
1999-09-28
2003-03-04
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Web, sheet or filament bases; compositions of bandages; or...
C424S400000, C424S078020, C424S443000, C424S402000, C424S448000, C514S772200, C514S817000, C514S944000
Reexamination Certificate
active
06528086
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to methods, formulations, and apparatus that allow fluid and less-than-solid pharmaceutical formulations to be applied onto certain human body surfaces and then be converted into a more solid state, thereby facilitating administration and removal of the formulation after application.
This invention also relates to methods and formulations that can anesthetize the skin or certain compromised human body surfaces and proximate tissues, such as skin having an abrasion, laceration, or post-surgery wound. More specifically, the present invention relates to less-than-solid anesthetic formulations and delivery systems that can be applied to the skin or compromised surfaces and subsequently converted to a soft coherent solid state and then peeled off the after the anesthetic effect is achieved.
In addition, this invention relates to applying formulations in which most of the local anesthetic agents are applied in an undissolved state onto a human body surface which is substantially lacking a barrier or layer of the skin, such as the stratum corneum, for obtaining more controlled and extended release of the local anesthetic agent(s).
2. Background of the Invention
Many medical formulations topically applied onto human body surfaces are in the form of pastes, gels, ointments, cream, solutions similar less than solid states that are vulnerable to being wiped off inadvertently or flowing away from the application site. For example, after a solution formulation is applied onto human skin, it can flow away quickly and thus result in a short contact time with the original application site. After a cream is applied onto the skin of an arm, it can be rubbed off in the daily activities if not protected by a cover. If a minoxidil cream or solution is applied onto the scalp for promoting hair growth before sleeping, it can be rubbed off on the pillow overnight. In addition, many “less-than-solid” formulations are messy and take an effort to remove.
Topical delivery of anesthesia is a good example of how prior art delivery methods and formulations are limited. Medical procedures on the skin are often painful. Most people are familiar with the pain and discomfort associated with minor procedures on the skin, such as receiving stitches or having a mole removed. Patients undergoing these procedures appreciate the benefits of fast and effective anesthesia. Even recently developed cosmetic procedures, such as laser resurfacing of skin and laser removal of port wine stain or similar birth marks, require significant anesthesia. Cosmetic procedures on facial skin can be especially painful. Currently, several prior art methods may be used to anesthetize the skin before administering these medical and cosmetic procedures, including general anesthesia or regional nerve block by injection, local anesthesia delivered by injection, and local anesthesia delivered topically, such as applying a eutectic mixture of local anesthetic cream (EMLA cream) onto the skin.
Prior art methods for anesthetizing skin have serious drawbacks. General anesthesia or regional nerve block by injection usually requires the involvement of an anesthesiologist and typically cannot be performed in a private practice setting. Injection of local anesthetic is painful, invasive, and may change the shape of the skin surface. It will also leave needle holes in the skin and may scab or scar. The disadvantages of needle injection may be especially unacceptable when the anesthesia is to be delivered to the facial tissues. While the use of EMLA cream is noninvasive, the onset time is often too long. Additionally, EMLA cream needs to be covered with an occlusion membrane while waiting for the anesthetic effect and EMLA cream leaves a mess on the skin which needs to be removed after the anesthetic is delivered.
Just as patients benefit from effective anesthetizing of the skin for certain medical and cosmetic procedures, patients experiencing discomfort as the result of compromised human body surfaces and the procedures associated with treating compromised surfaces can also benefit from convenient local anesthesia. Patients with open wounds, such as abrasions, lacerations, or ulcers may require anesthesia to control pain and to cleanse or close the wound. Chronic ulcer surfaces, surfaces that have scabs and dead tissues (i.e. recovering burn wound), need to be debrided from time to time.
Debridement is a painful procedure if anesthesia is not provided. General analgesia, intravenous narcotic analgesics, regional nerve block by injection, and epidural anesthesia may be used to control the pain associated with debridement or wounds. However, delivery of a general analgesic, regional nerve block by injection, epidural, or intravenous analgesic typically requires specially trained medical personnel and/or special medical equipment to administer. The procedures also expose patients to significant risks and expose care givers to significant liability. Applying analgesic formulation in which most of the active drug is dissolved onto skin lacking stratum corneum may result in dangerously rapid absorption of the drug and short duration of the effect.
Some local anesthetic agents used in the prior art formulations and apparatus of this invention to noninvasively anesthetize or provide analgesia to human body surfaces and tissues under the surface have significant limitations. Some commonly used local anesthetics, such as lidocaine have relatively limited penetration and sustain the analgesic effect for a relatively short period of time.
Thus, it would be advantageous to develop methods in which the formulation is in the less-than solid form, such as a paste, gel, ointment, cream or solution, before being applied onto a human body surface and then the formulation can be converted into a coherent, solidified gel by a certain mechanism during the application to facilitate removal. For some medications, it would also be advantageous if the means for converting the formulation into a coherent solid also included an occlusive cover that inhibited the evaporation of the solvent in the formulation and prevented the formulation from being rubbed off.
It would be particularly advantageous to develop methods and formulations to conveniently and noninvasively anesthetize the skin, especially the facial skin. It would also be advantageous to develop methods and formulations to more conveniently and safely anesthetize compromised human body surfaces. It would further be an advantage to develop an anesthetic formulation that can delivery anesthetic quickly and transdermally and that can be removed easily.
In this application, the phrase “less-than-solid phase,” “less-than-solid state,” or “less-than-solid form” means, unless specifically described otherwise, a form that is not as hard and as coherent as a solidified gel. Examples of such “less-than-solid” substances include toothpaste, cream, ointment, etc. One common property of these “less-than-solid” substances is that the substance is not strongly cohesive, or in other words, the substance is a liquid or a highly viscous fluid. In practical terms, a “less-than-solid” substance is a substance that one cannot grab and lift as a cohesive whole.
SUMMARY AND OBJECTS OF THE INVENTION
The present invention is directed toward a method and device for dermal delivery of a drug formulation. More specifically, the invention is a method and device for delivering a topically delivered drug using a formulation which is applied to a patient's skin as a fluid, moldable, or less-than-solid drug formulation, but which can be subsequently converted to a coherent, soft solid phase to facilitate removal of the formulation.
The formulation generally comprises a topically delivered drug, a conversion agent, and a vehicle medium or carrier. The drug is dispersed in the carrier. The conversion agent may be included in the drug formulation with the vehicle medium (carrier) and the drug or may be added following the application of the formulation. At the time of appl
Ghali Isis
Kirton & McConkie
Krieger Michael F.
Page Thurman K.
Zars, Inc.
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