Re: Paraquat and Oxygen

[Guest guest]

In a message dated 12/1/1999 21:00:56 Central Standard Time,

dfluffy01@... writes:

Thanks Matt. This is great stuff and should be appreciated by those who

can't run out and buy Goldfrank's (I paid something like $129.00 for it

--worth every penny.)

Gene Gandy

<< Subj: [texasems-L] Re: Paraquat and Oxygen

Date: 12/1/1999 21:00:56 Central Standard Time

From: dfluffy01@... ( Webb)

Reply-to: <A HREF= " mailto:egroups " >egroups</A>

To: egroups

*DING, DING, DING* " We have a winner. " Mr. Cloud is correct, Paraquat

(1,1'-dimethyl-4-4'-bipyridylium dichloride; CAS no. 1910-42-5) " In the

pneumocyte, cellular injury is initiated by the NADPH-dependent reduction of

paraquat to the monocation radical (PQ+). Spontaneous reaction with

molecular oxygen yields dication, which can be reduce again. This process,

known as the redox cycle, is sustained by the extensive supply of electrons

and oxygen in the lung. This and subsequent reactions explain why oxygen

enhances the toxicity of paraquat and paraquat inhances the toxicity of

oxygen.

" Dismutation of the superoxide species, which is catalyzed by superoxide

dismutates, leads to the formation of hydrogen peroxide. This can in turn be

metabolized to water by catalysis or peroxidases. Superoxide and hydrogen

peroxide also undergo a series of iron-catalyzed reactions to yield hydroxyl

free radicals (OH). These are highly toxic themselves and can also generate

more free radicals by reacting with other biomolecules, such as proteins or

membrane fatty acids. For example, the abstraction of hydrogen from

polyunsaturated fatty acids by OH forms a lipid radical and subsequently

lipid peroxidation, leads to degradation of cell membranes. The oxygen

species, in reacting with DNA, proteins, and cell membranes disrupt cellular

function and lead to cell death. The amplified generation of oxygen radicals

explains why the cellular injury from paraquat far exceeds that likely to be

produced by the initial reaction products. "

(Goldfrank's Toxicological Emergencies, 5th ed. pg 1144.)

Short version, " Oxygen bad " . ( Webb, 1999)

Paraquat (Uraquat, Diquat) is a inhalation, ingestion, contact poison

hazard. " Because ingestion of paraquat is most likely to produce a fatal

outcome, it should be asked about specifically, even in patients who appear

to only have inhalational, dermal, or ocular contact with the herbicide. "

(Goldfrank's)

Signs and Symptoms:

Contact: eye irritation (due to stripping of the superficial epithelium),

dermatitis, nail damage (nails become deformed, with formation of white

bands, ridging, deformity of the nail bed, and impaired growth).

Inhalation: epistaxis, airway inflammation, cough, and chest pain.

Ingestion:

Mild: (<20mg/kg) may be asymptomatic or develop only those symptoms and

signs referable to the GI tract, such as oral mucosal ulceration and

diarrhea. Patients recover with intervention/difficulty.

Moderate: (20-40mg/kg) usually die 5 days to several weeks after

ingestion. The most characteristic features of toxicity in these patients

are the early development of upper GI tract corrosion and acute renal

tubular necrosis and the later development of pulmonary fibrosis. The renal

failure usually resolves in accordance with the natural history of acute

tubular necrosis. Death is due to extensive pulmonary injury. (don't give

oxygen!!)

Severe: (>40mg/kg) usually die 1-5 days after ingestion from multi-organ

failure or the corrosive effects of paraquat on the GI tract. Death from

esophageal perforation and mediastinitis can occur within 2-3 days of

ingestion.

Treatment:

Inhalation: remove from source, decontaminate thoroughly. Patient will

most likely recover without major intervention (in other words, observe).

OXYGEN SHOULD NOT BE NEVER BE GIVEN AS AN INITIAL MEASURE, BECAUSE IT

POTENTIATES PARAQUAT TOXICITY. Supplemental oxygen is administered when

arterial oxygen tension falls below 50mm Hg and/or the patients has symptoms

of (severe) respiratory distress.

Contact: remove clothing, decontaminate with soap and water (pay attention

to underarms, groin, anus, skin folds). DO NOT use scrubbing brushes as they

abrade the skin and could thus increase transdermal absorption. Flush eyes

with copious amounts of water for at least 15 minutes (duh).

Ingestion: Patients invariably vomit due to the irritant qualities of

paraquat, as well as to the emetic that is added to the solution. There is

no place for syrup of ipecac, however, due to the time delay involved

between admission and vomiting. Instead, 1-2g/kg of activated charcoal,

1-2g/kg of Fullers earth in a 15% (wt/vol) aqueous suspension, or 1-2 g/kg

of bentonite in a 7% (wt/vol) aqueous slurry. The adsorbent should be given

with a cathartic, such as magnesium salt or one of the osmotic agents, 70%

sorbitol (2mL/kg), or 20% mannitol (3mL/kg).

A second and third dose of adsorbent should be given at 4-hour intervals

to ensure that the absorption of paraquat is reduced as much as possible.

Subsequent doses are given with a cathartic only if the previous dose has

not passed through the GI tract and appeared per rectum.

Fluids should be administered IV in sufficient volume to replace losses

from the GI tract due to mucosal damage produced by paraquat, emesis, and

the cathartic. To prevent renal failure, urine output should be measured and

maintained at least at normal flow rates. Some advocate forced diuresis,

although this does NOT increase the renal clearance of paraquat

significantly.

Supplemental oxygen is administered when arterial oxygen tension falls

below 50mm Hg and/or the patients has symptoms of (severe) respiratory

distress.

I hope this answers everyones questions. Dr. Bledsoe, feel free to add

anything you would like. Everything in this post is taken from " Goldfrank's

Toxicologic Emergencies, 5th ed. pg: 1141-1148. I left out the stuff on

hemodialysis. If a patient presents with Paraquat poisoning, PLEASE

encourage the physician to read the book to see if s/he wishes to begin

hemodialysis and/or charcoal hemoperfusion, the later of which has been

shown to be possibly helpful.

Excuse the spelling errors, I didn't feel like spell checking this post.

My opinions are just that, my opinions. They are much like my advice,

free and worth exactly what you pay for them.

Webb

dfluffy01@...

______________________________________________________

------------------------------------------------------------------------

-- Easily schedule meetings and events using the group calendar!

-- /cal?listname= & m=1

----------------------- Headers --------------------------------

Return-Path: <-return-8162-wegandy=aol.comreturns (DOT) >

Received: from rly-yh01.mx.aol.com (rly-yh01.mail.aol.com [172.18.147.33])

by air-yh01.mail.aol.com (vx) with ESMTP; Wed, 01 Dec 1999 22:00:56 -0500

Received: from mu. (mu. [207.138.41.151]) by

rly-yh01.mx.aol.com (v65.4) with ESMTP; Wed, 01 Dec 1999 22:00:23 -0500

X-eGroups-Return: -return-8162-wegandy=aol.comreturns (DOT)

Received: from [10.1.2.1] by mu. with NNFMP; 02 Dec 1999 02:59:02

-0000

Received: (listserv 1.289); by m5; 02 Dec 1999 02:59:02 -0000

Delivered-To: listsaver-egroups-egroups

Received: (qmail 27027 invoked from network); 2 Dec 1999 02:58:56 -0000

Received: from f103.law7.hotmail.com (HELO hotmail.com) (216.33.237.103) by

qg. with SMTP; 2 Dec 1999 02:58:56 -0000

Received: (qmail 73970 invoked by uid 0); 2 Dec 1999 02:58:56 -0000

Message-ID:

Received: from 198.250.153.245 by www.hotmail.com with HTTP; Wed, 01 Dec

1999 18:58:56 PST

X-Originating-IP: [198.250.153.245]

To: egroups

Date: Wed, 01 Dec 1999 20:58:56 CST

Mailing-List: contact -owneregroups

X-Mailing-List: egroups

Precedence: bulk

List-Help: </group//info.html>,

<mailto:-helpegroups>

List-Unsubscribe: <mailto:-unsubscribeegroups>

List-Archive: </group//>

Reply-To: egroups

Subject: [texasems-L] Re: Paraquat and Oxygen

MIME-Version: 1.0

Content-Type: text/plain; format=flowed

Content-Transfer-Encoding: 7bit

>>