page148
Monomax
c
(Chiesi)
Monomax
c
SR, capsules,
m/r,
isosorbide mono-
nitrate 40 mg,
net price 28-cap pack = £6.52;
60 mg,
28-cap pack = £8.86.
Label:
25
Dose
prophylaxis of angina,
40–60 mg daily in the morning,
increased if necessary to 120 mg daily
Note
Also available as
Angeze SR
c
Monomax
c
XL tablets,
m/r,
isosorbide mononitrate
60 mg,
net price 28-tab pack = £5.25.
Label:
25
Dose
prophylaxis of angina, 1 tablet in the morning (half a tablet
for first 2–4 days to minimise possibility of headache), increased if
necessary to 2 tablets
Monomil XL
c
(TEVA UK) A
Tablets
, m/r, isosorbide mononitrate 60 mg, net price
28-tab pack = £3.98.
Label:
25
Dose
prophylaxis of angina, 1 tablet daily in the morning (half a
tablet daily for first 2–4 days to minimise possibility of headache),
increased if necessary to 2 tablets once daily
Monosorb XL 60
c
(Dexcel) A
Tablets
,
m/r,
f/c,
isosorbide mononitrate 60 mg,
net
price 28-tab pack = £16.66.
Label:
25
Dose
prophylaxis of angina, 1 tablet daily in the morning (half a
tablet for first 2–4 days to minimise possibility of headache),
increased if necessary to 2 tablets
Zemon
c
(Neolab)
Zemon 40XL tablets
,
m/r,
ivory,
isosorbide mono-
nitrate 40 mg,
net price 28-tab pack = £14.25.
Label:
25
Zemon 60XL tablets
,
scored,
m/r,
ivory,
isosorbide
mononitrate 60 mg,
net price 28-tab pack = £11.14.
Label:
25
Dose
prophylaxis of angina, 40–60 mg daily in the morning (half
a 60-mg tablet may be given for 2–4 days to minimise possibility
of headache),
increased if necessary to 80–120 mg once daily
2.6.2
Calcium-channel blockers
Calcium-channel
blockers
(less
correctly called ‘cal-
cium-antagonists’)
interfere with the inward displace-
ment
of
calcium ions
through the slow channels
of
active cell
membranes.
They influence the myocardial
cells, the cells within the specialised conducting system
of
the heart,
and the cells of
vascular smooth muscle.
Thus,
myocardial
contractility may be reduced,
the
formation and propagation of electrical impulses within
the heart may be depressed,
and coronary or systemic
vascular tone may be diminished.
Calcium-channel blockers differ in their predilection for
the various possible sites of action and,
therefore,
their
therapeutic effects
are disparate,
with much greater
variation than those of beta-blockers.
There are impor-
tant differences between verapamil,
diltiazem,
and the
dihydropyridine calcium-channel
blockers (amlodipine,
felodipine,
isradipine,
lacidipine,
lercanidipine,
nicar-
dipine, nifedipine, and nimodipine). Verapamil and dilti-
azem should usually be avoided in heart failure because
they may further depress cardiac function and cause
clinically significant deterioration.
Verapamil is used for the treatment of angina (section
2.10.1),
hypertension (section 2.5),
and arrhythmias
(section 2.3.2). It is a highly negatively inotropic calcium
channel-blocker and it reduces cardiac output, slows the
heart rate,
and may impair atrioventricular conduction.
It may precipitate heart failure,
exacerbate conduction
disorders,
and cause hypotension at
high doses and
should not
be used with beta-blockers
(see p.
133).
Constipation is the most common side-effect.
Nifedipine relaxes vascular smooth muscle and dilates
coronary and peripheral arteries. It has more influence
on vessels and less on the myocardium than does verap-
amil, and unlike verapamil has no anti-arrhythmic activ-
ity. It rarely precipitates heart failure because any nega-
tive inotropic effect
is
offset
by a reduction in left
ventricular work. Short-acting formulations of nifedipine
are not recommended for angina or long-term manage-
ment of hypertension; their use may be associated with
large variations
in blood pressure and reflex tachy-
cardia. Nicardipine has similar effects to those of nife-
dipine and may produce less reduction of
myocardial
contractility. Amlodipine and felodipine also resemble
nifedipine and nicardipine in their effects and do not
reduce myocardial contractility and they do not produce
clinical deterioration in heart failure. They have a longer
duration of
action and can be given once daily.
Nife-
dipine, nicardipine, amlodipine, and felodipine are used
for the treatment
of
angina (section 2.10.1)
or hyper-
tension.
All
are valuable in forms of angina associated
with coronary vasospasm.
Side-effects associated with
vasodilatation such as flushing and headache (which
become less
obtrusive after
a few days),
and ankle
swelling (which may respond only partially to diuretics)
are common.
Isradipine,
lacidipine,
and lercanidipine have similar
effects to those of
nifedipine and nicardipine;
they are
indicated for hypertension only.
Nimodipine is related to nifedipine but
the smooth
muscle relaxant
effect
preferentially acts on cerebral
arteries. Its use is confined to prevention and treatment
of
vascular spasm following aneurysmal
subarachnoid
haemorrhage.
Diltiazem is effective in most forms of angina (section
2.10.1);
the longer-acting formulation is also used for
hypertension. It may be used in patients for whom beta-
blockers are contra-indicated or ineffective. It has a less
negative inotropic effect than verapamil and significant
myocardial
depression
occurs
rarely.
Nevertheless
because of
the risk of
bradycardia it
should be used
with caution in association with beta-blockers.
Unstable angina
Calcium-channel
blockers do not
reduce the risk of
myocardial
infarction in unstable
angina.
The use of
diltiazem or
verapamil
should be
reserved for patients resistant to treatment with beta-
blockers.
Withdrawal
There is
some evidence that
sudden
withdrawal
of
calcium-channel
blockers may be asso-
ciated with an exacerbation of angina.
AMLODIPINE
Indications
hypertension,
prophylaxis of angina
Cautions
acute porphyria (but see section 9.8.2);
interactions: Appendix 1 (calcium-channel blockers)
Contra-indications
cardiogenic shock,
unstable
angina,
significant aortic stenosis
Hepatic impairment
may need dose reduction—half-
life prolonged
Pregnancy
no information available—manufacturer
advises avoid, but risk to fetus should be balanced
against risk of uncontrolled maternal
hypertension
Breast-feeding
manufacturer advises avoid—no
information available
128
2.6.2 Calcium-channel blockers
BNF 61
2
Cardiovascular system