Re: patent wording shows n-acetylcysteine also yields toxic cysteine

[Guest guest]

The fact that some of the n-acetylcysteine breaks down to form toxic cysteine as

soon as it starts to dissolve, before it's absorbed, is a concern mentioned in

its patent.

Worthy of note that the timed release formula only prolongs the process by

allowing the tablet to dissolve more slowly.

So we use undenatured whey or perhaps cystine to deliver bonded cysteine to

cells.

Here's a patent snip:

N-acetyl cysteine is a pharmaceutically active ingredient which dissolves or

reduces the viscosity of mucous as produced in the respiratory airways, and

including not only the lung tree but all the upper airways including the

cavities in the forehead and the cheeks, to prevent or treat sinusitis, to

thereby eliminate or reduce the symptoms of virus infections causing rhinitis,

bronchitis and other respiratory tract congestion.

N-acetyl cysteine can also be used as a scavenger to prevent cell death due to

free radicals, and to prevent nitrate intolerance following chronic treatment

with nitroglycerine and sustained release nitrate formulations. N-acetyl

cysteine also has value as a nutritional supplement. N-acetyl cysteine has few

reported side effects except an irritating effect on the mucous membrane in the

stomach. It also has an extremely bad taste which per se creates a great problem

in administering it.

Another of the problems of N-acetyl cysteine is that it is readily hydrolyzed by

a wide variety of enzymes, and is rapidly degraded and excreted from the body.

Thus, to maintain a reasonable blood level requires frequent consumption of

tablets.

N-Acetyl cysteine has hitherto been administered in the form of effervescent

compositions which are dissolved in water by a carbon dioxide generating system

prior to administration, or in the form of granules which are dissolved in water

prior to use, or in the form of a matrix tablet comprising a skeleton of an

insoluble polymer, which tablet leaks out N-acetyl cysteine into both the

gastric and intestinal juices.

The problem with currently-available granulated and effervescent tablet

compositions is that they release N-acetyl cysteine very rapidly. Thus, the

effervescent compositions as well as the granulate compositions currently

available on the market achieve a maximum blood plasma level within 1 hr from

administration. One matrix tablet formulation does show a maximum blood plasma

level at 2-2.5 hrs after administration, although its recipe indicates that

granulation was required. The problem with granulation of acetyl cysteine is

that if any dissolves, the dissolved material starts to decompose into

impurities. One solution that has been tried is granulation in methylene

chloride, which is a solvent of questionable toxicity and environmental effect.

In accordance with the present invention, this problem of overly-rapid release

is obviated by providing the N-acetyl cysteine in the form of a tablet or other

article made with the rheology modifying acrylic or methacrylic acid-based

polymers, or analogues, described in commonly-assigned application Ser. No.

09/559,687, filed Apr. 27, 2000. Tablets made in this manner exhibit controlled

release characteristics, thereby allowing the N-acetyl cysteine active

ingredient to be released over a longer period of time.

all good,

Duncan Crow