Lidocaine chemical structure
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Xylocaine

Lidocaine (INN) or lignocaine (former BAN) is a popular local anesthetic and a derivative of cocaine (without its stimulant properties) that is often used in dentistry or topically. The most commonly encountered lidocaine preparations are marketed by AstraZeneca under the brand names Xylocaine and Xylocard, though lidocaine is also found in many other proprietary preparations. more...

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History

Lidocaine, the first amide-type local anesthetic, was developed by Nils Löfgren and Bengt Lundqvist in 1943 and first marketed in 1948.

Also used in pet medications.

Pharmacology

Lidocaine is metabolized in the liver to pharmacologically active breakdown products which are excreted by the kidneys. It is faster acting and longer lasting than procaine (Novocain).

When given intravenously, lidocaine is a class Ib antiarrhythmic agent and will block the sodium channel of the cardiac action potential, which decreases automaticity by reducing the slope of phase 4 depolarization with little effect on the PR interval, QRS complex or QT interval.

This drug is used in the treatment of ventricular cardiac arrhythmias and cardiac arrest with ventricular fibrillation, especially with acute ischemia, though it is not useful in the treatment of atrial arrhythmias.

The elimination half life of intravenous lidocaine is about 109 minutes, but because it is metabolized in the liver (which depends on liver blood flow), dosage should be reduced in patients with low cardiac output or who are in shock. In patients with cardiogenic shock, the half life may exceed ten hours.

Toxicity

Toxicity is most often seen when there has been an inadvertent intravascular injection of lidocaine when being used as a local anesthetic. Central nervous system toxicity manifests as tinnitus, dizziness, paresthesia (pins and needles), confusion and – in more severe cases – seizures or coma. Severe toxicity may also result in cardiovascular system collapse or ventricular fibrillation.

Related Information

  • Benzocaine
  • Bupivacaine
  • Procaine
  • Cocaine


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Stem cell 'stunt' sparks skepticism among peers
From Cosmetic Surgery Times, 11/1/04 by John Jesitus

Austin, Texas -- A plastic surgeon's gambit to garner attention for the therapeutic potential of adult stem cells harvested through liposuction has drawn attention--and criticism--from his peers.

In September, Robert E. Ersek, M.D., F.A.C.S., assistant clinical professor at Southwestern Texas State University in San Marcos, Texas, performed self-liposuction under the watchful eye of liposuction pioneer Yves-Gerard Illouz, M.D., as TV cameras rolled.

As part of a recent symposium sponsored by The Lipoplasty University, where Dr. Ersek serves as dean, representatives from StemSource (now part of MacroPore Biosurgery) were present to teach his office staff how to store and ship tissue derived from liposuction to their San Diego facilities for long-term cryogenic storage.

Dr. Ersek, who had also recruited a patient for a demonstration, decided to collect his own aspirate to assure patients about the safety of the procedure.

'History of embracing'

Dr. Ersek has a history of embracing the vanguard of cell-storage technology. In the 1970s, he stored his own sperm cells at a Minneapolis sperm bank that also has been used by Olympic cyclist Lance Armstrong. More recently, he banked umbilical stem cells harvested from his grandchildren.

Although he offers cell-harvesting services to all of his patients, Dr. Ersek says, "Not that many are interested because they've never heard of it. New ideas take awhile to grab hold, even really good ones. So I decided to store my own stem cells. And it occurred to me that in order to convince my patients that (the procedure) is very safe and simple, I decided to harvest the stem cells myself. So I put in some local anesthesia and performed the procedure entirely awake, just using Xylocaine with epinephrine. This was not a liposuction procedure for changing my size. We took out about one pound of fat just for the stem cell purpose."

StemSource later processed Dr. Ersek's tissue down to 150 cc of usable material, which yielded 4 million viable stem cells. The company stores such materials at minus 320 degrees Fahrenheit, charging patients $1,675 for five years' storage (or $600 initially plus $175 annually after the first year).

Media darling

A week before Dr. Ersek's procedure, his staff called a local newspaper.

"I thought it would get some attention," he tells Cosmetic Surgery Times. "I had no idea how much attention it would get. When the local paper did a little article, all three of the local TV stations had to be there when I did it. And they were fighting each other for an interview.

However, not all the attention Dr. Ersek's ploy has generated has been positive.

"It's not new," says Rod J. Rohrich, M.D., professor and chairman, plastic surgery, University of Texas Southwestern Medical Center, and president of the American Society of Plastic Surgeons (ASPS).

"We know stem cells are multipotential, and they have potential advantages in the future by being used to transform into cartilage, bone and any other type of tissue. But the problem is, we don't know if adult stem cells act the same as embryonic ones. And fat is very abundant. It's not like you're going to run out of fat at some point in your life."

Not many people have chosen to store stem cells, he adds, "Because the clinical applicability of it is quite far away. You can't just say, 'I lost my hand, so I'm going to (harvest) my stem cells, and we're going to grow a hand.' It doesn't work that way yet. Someday, we may be able to grow some body parts, or at least parts of them. But it's not quite clinically feasible yet. Let's not get out in front of the curve here. This is purely sensationalism."

Experimental

Jeffrey M. Kenkel, M.D, associate professor and vice chairman (and director, The Clinical Center for Cosmetic Laser treatment), department of plastic surgery, the University of Texas Southwestern at Dallas, says, "It is still very much experimental without any conclusive data about how adult stem cells could be used in the future. Cost is also something to consider, with many companies charging in excess of $3,000 (to harvest and store stem cells)."

"There's a lot of confusion among patients and physicians about embryonic versus adult stem cells;' counters Elizabeth Scarbrough, vice president of marketing and development for MacroPore. "Embryonic stem cells have terrific potential, but they're probably 10 to 20 years from clinical applicability. Embryonic cells are designed to build a body or body parts, while adult stem cells are designed to heal and repair. It's an educational challenge, but we are very clear with patients and physicians that this is emerging science with no guarantees."

Challenges

Scientific challenges that researchers must overcome with treatments derived from embryonic stem cells include their potential for rejection and tumor formation.

In contrast, MacroPore's use of autologous adult cells eliminates risks of rejection and disease transmission.

"With adult stem cells," Ms. Scarbrough adds, "you don't have the problem of tumor formation. Adult stem cells from bone marrow have been used for 30 years in bone marrow transplants, so we know that they're safe."

Moreover, liposuction provides a convenient source of adult stem cells, unlike the process of extracting the cells from bone marrow or other locations. However, adult stem cells lack the pluripotency of embryonic ones, which theoretically can differentiate into any cell of the human body.

Reason for storage

"One of the reasons to store stem cells is the fact that as we get older, our stem cells are less potent, so to speak," Dr. Ersek adds. "Therefore, 20 years from now if I have a broken hip or something and some of these stem cells (harvested now) are used to make new bone tissue, they'll be younger cells with that much more viability. Another reason is that if you knew what kind of illness you were going to get, you could plan for it. But we never know. And if you get cancer that requires extreme radiotherapy or chemotherapy, it could knock out your bone marrow. So you have no blood-making cells. Having stem cells stored makes it possible that you could repopulate your own bone marrow with your own cells."

For now, Dr. Rohrich says, "We don't want to be promising patients more than is now clinically available or applicable. The premise is, under-promise and over-deliver. We don't want to do the opposite here. I wouldn't rush to get your fat stored in a stem cell bank. There's plenty of time to do that, and there's a lot of technology that's coming out that may supersede all that."

Reason for publicity

Dr. Ersek counters, "The reason I think it's important to get some publicity is, my practice does about 10 cases a week of liposuction. Patients might average 10 pounds of tissue (removed), so if you multiply that out, that's about 5,000 pounds of fat a year going right down the tube. Some of those people are going to get cancer, leukemia or other serious illnesses later in life. So it's my responsibility to let them know stem cell banking is available. And who knows what's going to happen in the next couple years? Stem cell research is hot stuff these days. And this approach avoids the whole problem of embryonic stem cells. Ten years from now, or maybe five, more plastic surgeons will be doing it."

Healthy skepticism

Already, the recently concluded American Society of Plastic Surgeons annual meeting included three presentations by research teams studying topics including preservation of adipose aspirates as a potential stem cell source and de novo fabrication of tissue flaps and organs ex vivo using a bioreactor.

"Healthy skepticism is a good thing," Ms. Scarbrough says. "Everyone has reason to be cautious and to question any emerging technology. I happen to be close enough to the data that's coming out of countless reputable institutions to believe that this technology is ultimately going to change the way we practice medicine."

Disclosures: Drs. Ersek, Rorich and Kenkel possess no financial interests relative to this article. (Dr. Ersek paid his own processing and storage fee.)

For more information:

www.lipou.org/

www.macropore.com/usa_products/usa_biologics.php

www.personique.com/

COPYRIGHT 2004 Advanstar Communications, Inc.
COPYRIGHT 2004 Gale Group

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