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Movements, leaders, victories and the continuing fight for equality.
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Meet the people whose lives, choices and achievements shaped the journey.
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Wilmington, North Carolina once had a thriving Black middle class and an elected interracial government. In 1898 white supremacists used violence to overthrow that government, kill Black residents and drive many others from the city.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
Transdermal is a route of administration wherein active ingredients are delivered across the skin for systemic distribution. Examples include transdermal patches used for medicine delivery. The drug is administered in the form of a patch or ointment that delivers the drug into the circulation for systemic effect.
Although the skin is a large and logical target for drug delivery, its basic functions limit its utility for this purpose. The skin functions mainly to protect the body from external penetration (by e.g. harmful substances and microorganisms) and to contain all body fluids.
There are two important layers to the human skin: (1) the epidermis and (2) the dermis. For transdermal delivery, drugs must pass through the two sublayers of the epidermis to reach the microcirculation of the dermis.
The stratum corneum is the top layer of the skin and varies in thickness from approximately ten to several hundred micrometres, depending on the region of the body.[1] It is composed of layers of dead, flattened keratinocytes surrounded by a lipid matrix, which together act as a brick-and-mortar system that is difficult to penetrate.[2]
The stratum corneum provides the most significant barrier to diffusion. In fact, the stratum corneum is the barrier to approximately 90% of transdermal drug applications. However, nearly all molecules penetrate it to some minimal degree.[3] Below the stratum corneum lies the viable epidermis. This layer is about ten times as thick as the stratum corneum; however, diffusion is much faster here due to the greater degree of hydration in the living cells of the viable epidermis. Below the epidermis lies the dermis, which is approximately one millimeter thick, 100 times the thickness of the stratum corneum. The dermis contains small vessels that distribute drugs into the systemic circulation and regulate temperature, a system known as the skin's microcirculation.[2][3]
There are two main pathways by which drugs can cross the skin and reach the systemic circulation. The more direct route is known as the transcellular pathway.
By this route, drugs cross the skin by directly passing through both the phospholipid-rich membranes and the cytoplasm of the dead keratinocytes that constitute the stratum corneum.
Although this is the path of shortest distance, the drugs encounter significant resistance to permeation. This resistance is caused because the drugs must cross the lipophilic membrane of each cell, then the hydrophilic cellular contents containing keratin, and then the phospholipid bilayer of the cell one more time. This series of steps is repeated numerous times to traverse the full thickness of the stratum corneum.[1][2]
The other more common pathway through the skin is via the intercellular route. Drugs crossing the skin by this route must pass through the small spaces between the cells of the skin, making the route more tortuous. Although the thickness of the stratum corneum is only about 20 μm, the actual diffusional path of most molecules crossing the skin is on the order of 400 μm.[4] The 20-fold increase in the actual path of permeating molecules greatly reduces the rate of drug penetration.[3]
Recent research has established that the intercellular route can be dramatically enhanced by attending to the physical chemistry of the system solubilizing the active pharmaceutical ingredient, rendering a dramatically more efficient delivery of payload and enabling the delivery of most compounds via this route.[5][6][7]
A third pathway to breach the Stratum Corneum layer is via tiny microchannels created by a medical micro-needling device of which there are many brands and variants.[8] Investigations at the University of Marburg, Germany, using a standard Franz diffusion cell showed that this approach is efficient in enhancing skin penetration ability for lipophilic as well as hydrophilic compounds.[9]
The micro-needling approach is also seen as 'the vaccine of the future'.[10] The microneedles can be hollow, solid, coated, dissolving, or hydrogel-forming.[11] Some have regulatory approval.[11] Microneedle devices/patches can be used to deliver nanoparticle medicines.[12]
Devices and formulations for transdermally administered substances include transdermal patches and transdermal gel.
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Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
Transdermal is a route of administration wherein active ingredients are delivered across the skin for systemic distribution. Examples include transdermal patches used for medicine delivery. The drug is administered in the form of a patch or ointment that delivers the drug into the circulation for systemic effect.
Transdermal implants, or dermal piercings, are a form of body modification used both in a medical and aesthetic context that, in contrast to subdermal implants, consist of an object placed partially below and partially above the skin, thus implanted transdermal. Two techniques are prevalent using post-like and microdermal implants respectively. Although the skin around such implants generally heals as if it were a piercing, in the body piercing community, these types of modification are commonly called fairly "heavy" due to the complexity of the procedure and potential social implications.
A transdermal patch is a medicated adhesive patch that is placed on the skin to deliver a specific dose of medication through the skin and into the bloodstream. An advantage of a transdermal drug delivery route over other types of medication delivery (such as oral, topical, intravenous, or intramuscular) is that the patch provides a controlled release of the medication into the patient, usually through either a porous membrane covering a reservoir of medication or through body heat melting thin layers of medication embedded in the adhesive. The main disadvantage to transdermal delivery systems stems from the fact that the skin is a very effective barrier; as a result, only medications whose molecules are small enough to penetrate the skin can be delivered by this method. The first commercially available prescription patch was approved by the U.S. Food and Drug Administration in December 1979. These patches administered scopolamine for motion sickness. In order to overcome restriction from the skin, researchers have developed microneedle transdermal patches (MNPs), which consist of an array of microneedles, which allows a more versatile range of compounds or molecules to be passed through the skin without having to micronize the medication beforehand. MNPs offer the advantage of controlled release of medication and simple application without medical professional assistance required. With advanced MNPs technology, drug delivery can be specified for local usage, for example skin whitener MNPs that are applied to the face. Many types of MNPs have been developed to penetrate tissues other than skin, such as internal tissues of the mouth and digestive tract. These promote faster and more direct delivery of the molecule to the targeted area.
A transdermal analgesic or pain relief patch is a medicated adhesive patch used to relieve minor to severe pain. There are many types of analgesic patches based on the main ingredients in the patches. These include patches containing counterirritants, which are used to treat mild to moderate pain, and patches containing opioids such as buprenorphine and fentanyl, used to relieve moderate to severe pain. Fentanyl is often used for opioid-tolerant patients. Nitroglycerin, also known as glyceryl trinitrate (GTN), a medication used for heart failure, high blood pressure, anal fissures, painful periods, and to treat and prevent chest pain, can also be found in patches. Beyond these are patches that contain drugs such as diclofenac and lidocaine and various other drugs. The main purpose of transdermal analgesic patches is to administer drugs in a more viable way to patients, as opposed to oral consumption or intravenous administration such as an injection.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Shirley Chisholm, elected in 1968.