A1,
A2,
B,
C1,
C2,
D,
E,
F,
G-H,
I-K,
L,
M,
N,
O,
P1,
P2,
Q-R,
S,
T,
U-V,
W-Z
Actidose Aqua Pharmacology, Pharmacokinetics, Studies, Metabolism - Actidose
Actidose Aqua Pharmacology, Pharmacokinetics, Studies, Metabolism - Actidose
CLINICAL PHARMACOLOGY
Activated Charcoal
Activated charcoal is produced by pyrolysis of organic material, such
as wood, and an activation process which cleanses and fragments the charcoal
by exposure to an oxidizing gas compound of steam, oxygen, and acids at
high temperature resulting in increased surface area through the creation
of numerous external and internal pores. These pores serve as reservoirs
to adsorb substances admixed with activated charcoal, making it a useful
adsorbent for specified toxins.
Activated charcoal is pharmacologically inert and is not absorbed in
the gastrointestinal tract. Activated charcoal will adsorb a variety of
organic and inorganic substances, but is especially effective in adsorbing
compounds within a molecular weight range of 100 to 1,000 Daltons (AMU’s).1
Several other physiologic and physicochemical factors influence the adsorptive
capacity of activated charcoal including: pH, charcoal: drug ratio, gastric
contents, and adsorption kinetics.2
Much of the published scientific literature which studied the adsorptive
capacity of activated charcoal was conducted using in vitro models. A
considerable amount of the research may be invalid since the effects of
physiologic pH were not taken into consideration or held constant. Using
research models which simulate the gastric environment, some toxins were
not adsorbed by activated charcoal. This data was inappropriately extended
to imply that activated charcoal did not adsorb a toxin and therefore
had no efficacy in the management of that type of poisoning incident.
However, the research failed to consider that the increased pH of the
small intestine provides a receptive environment for the adsorption of
the toxin by activated charcoal. Activated charcoal will effectively adsorb
acidic, alkaline and neutral substances (not to suggest use of activated
charcoal in poisonings caused by corrosive agents2). The extent
of adsorption will be dependent upon the relative solubility of the drug
at a specified pH.
The optimal dosage ratio of activated charcoal to toxin is described
as 10:13,4,17,18 Numerous factors contribute to and interfere
with adsorptive capacity, therefore, the 10:1 ratio may not be valid in
the clinical setting. Furthermore, a primary application of activated
charcoal is in adult patients who have intentionally ingested a toxin
for drug abuse or suicidal purposes. These patients may not freely provide
information about the substance or amount ingested, or have a decreased
level of consciousness. Under these conditions it is difficult to determine
the ingestion history, making it impractical to use the 10:1 ratio. The
10:1 ratio is also impractical when large amounts of toxin have been ingested
(i.e., an overdose of 50 gm of aspirin would then require 500 gm [1.1
lbs.] of activated charcoal).
Gastric contents may also compete with ingested toxins and compromise
the adsorption of the toxins by activated charcoal.2 If activated
charcoal is to be administered to a patient known to have ingested a large
meal in close proximity to the time of treatment, a larger dose of activated
charcoal may be appropriate.
Under appropriate physiologic conditions activated charcoal adsorbs toxins
instantaneously. This adsorptive process is reversible and an equilibrium
between free and bound toxin will exist. According to the wlaw of mass
action the amount of free drug decreases as the dose of activated charcoal
increases. Therefore, large doses of activated charcoal can favor for
equilibrium toward greater toxin adsorption and efficacy. There is limited
evidence that desorption of a toxin from activated charcoal may occur.19
Therefore, there is a potential for toxin readsorption and enhanced toxicity.
The current standard of care is to administer a cathartic with single
doses of activated charcoal to hasten the elimination of the toxin/activated
charcoal complex from the gastrointestinal tract.5 Cathartica
should be used with extreme care during multiple dose activated charcoal
therapy and it is not recommended to use a cathartic with each dose of
activated charcoal.5
Sorbitol
Sorbitol is a hexahydric sugar alcohol which primarily serves as an camotic
catharticin Actidose with Sorbitol, secondary advantage of using sorbitol
is as a palatability enhancer to decrease the innate gritty texture of
activated charcoal and to provide a sweet vehicle to increase patient
compliance. Sorbitol is poorly absorbed during its transit through the
gastrointestinal tract. Absorbed sorbitol is metabolized by the liver
and slowly converted to fructose. Insulin is not necessary for intracellular
transport of sorbitol, therefore customary cathartic doses can be safely
used by patients with diabetes mellitus.
As a hyperosmotic cathartic sorbitol produces a hygroscopic action resulting
in increased water in the large intestine and increased intraluminal pressure
which stimulates catharsis. Studies have been conducted in healthy adult
human volunteers using therapeutic amounts of activated charcoal and sorbitol.8,9
Catharsis of activated charcoal occurred in an average of 10-15 hours
and persisted for 8-12 hours. Fourteen poisoned patients are reported
in one series representing a wide range of toxins and dosages of sorbitol
resulting in the onset of catharsis in an average of 7.7 hours.10
The onset of action may be expected to be longer in patients who have
ingested toxins which decrease bowel motility, such as pharmacological
agents and plants with anticholinergic properties, and drugs like narcotics.20
Sorbitol does not compromise the adsorptive capacity of activated charcoal.
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