Aluminium Glycinate
A white or almost white, odourless or almost odourless, pow-
der. The BP specifies 34.5 to 38.5% of A110, calculated on
the dried substance, and not more than 12% loss of weight on
drying. The USP specifies not more than 14.5% loss on dry-
ing. Practically insoluble in water and organic solvents: dis-
solves in dilute mineral acids and solutions of alkali
hydroxides. A 4% suspension in water has a oH of 6.5 to 7.5.
Aluminium glycinate is an antacid with general properties
Similar to those of aluminium hydroxide whose details are given below. It has been
Given in doses of up to 1 gm by mouth.
ALUMINIUM HYDROXIDE
Aluminum Hydroxide Gel (USP 23) is a suspension of amor-
phous aluminium hydroxide in which there is a partial substi-
tution of carbonate for hydroxide. It is a white viscous
suspension from which small amounts of clear liquid may
separate on standing. It has a pH of between 5,5 and 8.0.
Dried Aluminum Hydroxide Gel (USP 23) is an amorphous
form of aluminium hydroxide in which there is a partial sub-
stitution of carbonate for hydroxide. It contains the equivalent
of not less than 76.5% of AKOH)] and may contain varying
quantities of basic aluminium carbonate and bicarbonate. In
the labelling requirements the USP states that I g of dried alu-
minum hydroxide gel is equivalent to 765 mg of AKOH);. It
is a white, odourless, tasteless, amorphous powder. Practical-
ly insoluble in water and in alcohol: soluble in dilute mineral
acids and in solutions of alkali hydroxides. A 4% aqueous dis-
persion has a pH of not more than 10.0. Store in airtight con-
tainers.
Algeldrate (USAN. pINN) is defined as s hydrated aluminium
hydroxide with the general formula of A1(OH)3,xH2O.
Adverse Effects and Precautions
Aluminium hydroxide in common with other alu-
minium compounds is astringent and may cause
constipation: large doses can cause intestinal ob-
struction.
Excessive doses, or even normal doses in patients
with low-phosphate diets, may lead to phosphate de-
pletion accompanied by increased bone resorption
and hypercalciuria with the risk of osteomalacia.
Aluminium salts are not, in general, well absorbed
from the gastro-intestinal tract, and systemic effects
are therefore rare in patients with normal renal func-
tion. However, care is necessary in patients with
chronic renal impairment, since osteomalacia or
adynamic bone disease, encephalopathy;dementia,
and microcytic anaemia, have been associated with
aluminium accumulation in patients with chronic re-
nal failure who received large doses of aluminium
hydroxide as a phosphate-binding agent. Similar ad-
verse effects have also been associated with the alu-
minium content of dialysis fluids.
Aluminium hydroxide used as an adjuvant in ad-
sorbed vaccines has been associated with the forma-
tion of granulomas.
Aluminium accumulation does not generally appear to be sig-
nificant in patients with normal renal function taking thera-
peutic doses of aluminium-containing antacids and there is
little evidence that aluminium containing antacids are a risk
factor for Aizheimer's disease. Elevated plasma-aluminium
concentrations have been reported in infants with normal re-
nal function given aluminium-containing antacids but there
were no obvious signs of toxicity. However, aluminium ac-
cumulation resulting in osteomalacia or encephalopathy with
seizures and dementia has been reported in children with re-
nal failure treated with aluminium-containing phosphate
binders. Aluminium-containing antacids should therefore
be used with caution in patients with chronic renal failure,
especially in children.
Oral citrate salts increase the absorption of aluminium from
the gastro-intestinal tract and patients with renal failure tak-
ing aluminium compounds should avoid citrate-containing
preparations, which include many effervescent or dispersible
tablets. Ascorbic acid has also been reported to enhance
aluminium absorption.
Interactions
aluminium compounds used
as antacids interact with many other drugs, both by
alterations in gastric pH and emptying, and by direct
adsorption and formation of complexes that are not
absorbed. Interactions can be minimised by giving
the antacid and any other medication 2 to 3 hours
apart.
Pharmacokinetics
Aluminium hydroxide, given by mouth, slowly re-
acts with the hydrochloric acid in the stomach lo
form soluble aluminium chloride, some of which is
absorbed. The presence of food or other factors
which decrease gastric emptying prolongs the avail-
ability of aluminium hydroxide to react and may in-
crease the amount of aluminium chloride formed.
About O.1 to 0.5 mg of the cation is reported to be
absorbed from standard daily doses of an alumini-
um-containing antacid, leading to about a doubling
of usual aluminium concentrations in the plasma of
patients with normal renal function.
Absorbed-aluminium is eliminated in the urine, and
patients with renal failure are therefore at particular
risk of accumulation (especially in bone and the
CNS), and aluminium toxicity.
The aluminium compounds remaining in the gastro-
intestinal tract, which account for roost of a dose.
form insoluble, poorly absorbed aluminium salts in
the intestines including hydroxides, carbonates,
phosphates and fatty acid derivatives, which are ex-
creted in the faeces.
Uses and Administration
Aluminium hydroxide is used as an antacid
It is given in doses of up to about I g by
mouth. Aluminium hydroxide raises gastric pH
more slowly than calcium or magnesium antacids
and passage through an empty stomach may be too
rapid for it to exert any significant acid-neutralising
effect. In order to compensate for this and to reduce
the constipating effects, aluminium hydroxide is of-
ten given in association with a magnesium-contain-
ing antacid, such as magnesium oxide or
magnesium hydroxide.
Aluminium hydroxide binds phosphate in the gas-
tro-intestinal tract to form insoluble complexes and
reduces phosphate absorption. It is thus used to treat
hyperphosphataemia in patients with chronic renal
h failure. With this
use the dose must be adjusted to the individual pa-
tient's requirement but up to about 10 g a day by
mouth may be given in divided doses.
Aluminium hydroxide is also used as an adjuvant in
dsorbed vaccines.
Polymyositis and dermatomyositis. Corticosteroids
form the basis of the management of polymyositis
but the calcinosis that may occur in dermatomyositis does not
always respond well. Aluminium hydroxide 1.68 to 2.24 g
daily produced clinical improvement with complete clearing
of most calcified nodules after I year in a patient with calci-
nosis cutis complicating juvenile dermatomyositis. The cal-
cified masses are made up of hydroxyapatite and amorphous
calcium phosphate and reduction in phosphate absorption by
aluminium hydroxide probably helped to reverse their forma-
tion.