page65
can induce rebound acid secretion:
with modest doses
the clinical
significance is doubtful,
but prolonged high
doses also cause hypercalcaemia and alkalosis, and can
precipitate the milk-alkali syndrome.
Simeticone (activated dimeticone) is added to an anta-
cid as an antifoaming agent to relieve flatulence. These
preparations may be useful
for the relief
of
hiccup in
palliative care. Alginates, added as protectants, may be
useful in gastro-oesophageal reflux disease (section 1.1
and section 1.1.2). The amount of additional ingredient
or antacid in individual
preparations varies widely,
as
does their sodium content, so that preparations may not
be freely interchangeable.
See also section 1.3 for drugs used in the treatment of
peptic ulceration.
Hepatic impairment
In patients with fluid retention,
avoid antacids
containing large amounts
of
sodium.
Avoid antacids
that
cause constipation because this
can
precipitate
coma.
Avoid
antacids
containing
magnesium salts in hepatic coma if
there is a risk of
renal failure.
Renal
impairment
In patients with fluid retention,
avoid antacids
containing large amounts
of
sodium.
There is a risk of accumulation and aluminium toxicity
with antacids containing aluminium salts. Absorption of
aluminium from aluminium salts is increased by citrates,
which are contained in many effervescent preparations
(such as effervescent
analgesics).
Antacids containing
magnesium salts should be avoided or used at a reduced
dose because there is an increased risk of toxicity.
Interactions
Antacids should preferably not be taken
at the same time as other drugs since they may impair
absorption. Antacids may also damage enteric coatings
designed to prevent dissolution in the stomach. See also
Appendix 1 (antacids,
calcium salts).
Low Na
+
The words ‘low Na
+
’ added after some preparations
indicate a sodium content of
less than 1 mmol
per
tablet or 10-mL dose.
Aluminium- and magnesium-
containing antacids
ALUMINIUM HYDROXIDE
Indications
dyspepsia;
hyperphosphataemia (section
9.5.2.2)
Cautions
see notes above; interactions: Appendix 1
(antacids)
Contra-indications
hypophosphataemia;
neonates
and infants
Hepatic impairment
see notes above
Renal impairment
see notes above
Side-effects
see notes above
Aluminium-only preparations
Alu-Cap
c
(Meda)
Capsules
,
green/red, dried aluminium hydroxide
475 mg (low Na
+
).
Net price 120-cap pack = £3.75
Dose
antacid, 1 capsule 4 times daily and at bedtime; CHILD not
recommended for antacid therapy
Co-magaldrox
Co-magaldrox is a mixture of aluminium hydroxide and
magnesium hydroxide;
the proportions are expressed in the
form
x
/
y
where
x
and
y
are the strengths in milligrams per unit
dose of magnesium hydroxide and aluminium hydroxide
respectively
Maalox
c
(Sanofi-Aventis)
Suspension
,
sugar-free,
co-magaldrox 195/220
(magnesium hydroxide 195 mg,
dried aluminium
hydroxide 220 mg/5 mL (low Na
+
)). Net price 500 mL
= £2.79
Dose
ADULT and CHILD over 14 years, 10–20 mL 20–60 minutes
after meals and at bedtime or when required
Mucogel
c
(Chemidex)
Suspension
,
sugar-free,
co-magaldrox 195/220
(magnesium hydroxide 195 mg,
dried aluminium
hydroxide 220 mg/5 mL (low Na
+
)). Net price 500 mL
= £1.71
Dose
ADULT and CHILD over 12 years, 10–20 mL 3 times daily,
20–60 minutes after meals, and at bedtime or when required
MAGNESIUM CARBONATE
Indications
dyspepsia
Cautions
see notes above; interactions: Appendix 1
(antacids)
Contra-indications
hypophosphataemia
Hepatic impairment
see notes above
Renal impairment
see notes above;
magnesium
carbonate mixture has a high sodium content
Side-effects
diarrhoea;
belching due to liberated car-
bon dioxide
Aromatic Magnesium Carbonate Mixture, BP
(Aromatic Magnesium Carbonate Oral Suspen-
sion)
Oral suspension
,
light magnesium carbonate 3%,
sodium bicarbonate 5%,
in a suitable vehicle con-
taining aromatic cardamom tincture.
Contains about
6 mmol Na
+
/10 mL.
Net price 200 mL = 66p
Dose
10 mL 3 times daily in water
For preparations also containing aluminium,
see
above and section 1.1.2.
MAGNESIUM TRISILICATE
Indications
dyspepsia
Cautions
see under Magnesium Carbonate
Contra-indications
see under Magnesium Carbonate
Hepatic impairment
see notes above
Renal impairment
see notes above;
magnesium tri-
silicate mixture has a high sodium content
Side-effects
diarrhoea,
belching due to liberated car-
bon dioxide; silica-based renal stones reported on
long-term treatment
Magnesium Trisilicate Tablets, Compound, BP
Tablets
,
magnesium trisilicate 250 mg,
dried alumin-
ium hydroxide 120 mg
Dose
1–2 tablets chewed when required
Magnesium Trisilicate Mixture, BP
(Magnesium Trisilicate Oral Suspension)
Oral suspension
,
5% each of magnesium trisilicate,
light magnesium carbonate,
and sodium bicarbonate
in a suitable vehicle with a peppermint flavour.
Con-
tains about 6 mmol Na
+
/10 mL
Dose
10–20 mL in water 3 times daily or as required; CHILD 5–12
years,
5–10 mL in water 3 times daily or as required
For preparations also containing aluminium,
see
above and section 1.1.2.
BNF 61
1.1.1 Antacids and simeticone
45
1
Gastro-intestinal system