page133
also reported extrapyramidal disorders, urinary fre-
quency,
and incontinence
Dose
. Hypertension, initially 25 mg twice daily, increased by
25–50 mg daily at intervals of 2 weeks; max.
daily
dose 200 mg in 2–3 divided doses
Baratol
c
(Amdipharm) A
Tablets
,
blue,
f/c,
indoramin (as hydrochloride)
25 mg,
net price 84-tab pack = £9.00.
Label:
2
Doralese
c
A
Section 7.4.1 (prostatic hyperplasia)
PRAZOSIN
Indications
hypertension (see notes above); conges-
tive heart failure (but see section 2.5.5);
Raynaud’s
syndrome (see also section 2.6.4);
benign prostatic
hyperplasia (section 7.4.1)
Cautions
first dose may cause collapse due to hypo-
tension (therefore should be taken on retiring to bed);
elderly; cataract surgery (risk of intra-operative floppy
iris syndrome);
interactions: Appendix 1 (alpha-
blockers)
Driving
May affect performance of skilled tasks e.g. driving
Contra-indications
not recommended for congestive
heart failure due to mechanical obstruction (e.g. aortic
stenosis)
Hepatic impairment
initially 500 micrograms daily;
increased with caution
Renal impairment
initially 500 micrograms daily in
moderate to severe impairment; increased with cau-
tion
Pregnancy
no evidence of teratogenicity;
manufac-
turers advise use only when potential benefit out-
weighs risk
Breast-feeding
amount probably too small to be
harmful
Side-effects
see section 7.4.1;
also dyspnoea;
ner-
vousness; urinary frequency;
less commonly
insom-
nia,
paraesthesia, sweating,
arthralgia,
eye disorders,
tinnitus,
and epistaxis;
rarely
pancreatitis,
flushing,
vasculitis,
bradycardia, hallucinations,
worsening of
narcolepsy, gynaecomastia, urinary incontinence, and
alopecia
Dose
. Hypertension (see notes above), 500 micrograms 2–3
times daily for 3–7 days, the initial dose on retiring to
bed at night (to avoid collapse,
see Cautions);
increased to 1 mg 2–3 times daily for a further 3–7
days; further increased if necessary to max.
20 mg
daily in divided doses
. Congestive heart failure (but see section 2.5.5),
500 micrograms 2–4 times daily (initial dose at bed-
time,
see above), increasing to 4 mg daily in divided
doses;
maintenance 4–20 mg daily in divided doses
(but rarely used)
. Raynaud’s syndrome (but efficacy not established, see
section 2.6.4),
initially 500 micrograms twice daily
(initial dose at bedtime,
see above) increased,
if
necessary,
after 3–7 days to usual maintenance 1–
2 mg twice daily
Prazosin
(Non-proprietary) A
Tablets
,
prazosin (as hydrochloride) 500 micrograms,
net price 56-tab pack = £2.51;
1 mg,
56-tab pack =
£3.23; 2 mg, 56-tab pack = £4.39; 5 mg, 56-tab pack =
£8.75.
Counselling,
initial dose,
driving
Hypovase
c
(Pfizer) A
Tablets
,
prazosin (as hydrochloride) 500 micrograms,
net price 60-tab pack = £2.69;
1 mg,
scored,
60-tab
pack = £3.46.
Counselling,
initial dose,
driving
TERAZOSIN
Indications
mild to moderate hypertension (see notes
above); benign prostatic hyperplasia (section 7.4.1)
Cautions
first dose may cause collapse due to hypo-
tension (within 30–90 minutes,
therefore should be
taken on retiring to bed) (may also occur with rapid
dose increase);
cataract surgery (risk of intra-opera-
tive floppy iris syndrome); interactions: Appendix 1
(alpha-blockers)
Driving
May affect performance of skilled tasks e.g. driving
Pregnancy
no evidence of teratogenicity;
manufac-
turers advise use only when potential benefit out-
weighs risk
Breast-feeding
no information available
Side-effects
see section 7.4.1;
also reported
weight
gain, dsypnoea, paraesthesia, nervousness, decreased
libido,
thrombocytopenia,
back pain, and pain in
extremities
Dose
. Hypertension,
1 mg at bedtime (compliance with
bedtime dose important, see Cautions); dose doubled
after 7 days if necessary;
usual maintenance dose 2–
10 mg once daily; more than 20 mg daily rarely
improves efficacy
Terazosin
(Non-proprietary) A
Tablets
,
terazosin (as hydrochloride) 2 mg,
net price
28-tab pack = £2.16; 5 mg, 28-tab pack = £2.58; 10 mg,
28-tab pack = £7.88. Counselling, initial dose, driving
Hytrin
c
(Amdipharm) A
Tablets
,
terazosin (as hydrochloride) 2 mg (yellow),
net price 28-tab pack = £2.29; 5 mg (tan), 28-tab pack
= £4.29;
10 mg (blue),
28-tab pack = £8.57;
starter
pack (for hypertension) of 7 1-mg tabs with 21 2-
mg tabs = £13.00.
Counselling,
initial dose,
driving
Phaeochromocytoma
Long-term
management
of
phaeochromocytoma
involves
surgery.
However,
surgery should not
take
place until
there is adequate blockade of
both alpha-
and beta-adrenoceptors;
the optimal
choice of
drug
therapy remains unclear.
Alpha-blockers are used in
the short-term management
of
hypertensive episodes
in phaeochromocytoma.
Once alpha blockade is estab-
lished,
tachycardia can be controlled by the cautious
addition of a beta-blocker (section 2.4); a cardioselective
beta-blocker is preferred.
Phenoxybenzamine, a powerful alpha-blocker, is effec-
tive in the management of
phaeochromocytoma but it
has many side-effects.
Phentolamine is a short-acting
alpha-blocker
used mainly during surgery of
phaeo-
chromocytoma;
its
use for
the diagnosis
of
phaeo-
chromocytoma has been superseded by measurement
of catecholamines in blood and urine.
Metirosine
(available
from ‘special-order’
manufac-
turers or
specialist
importing companies,
see p.
988)
inhibits the enzyme tyrosine hydroxylase,
and hence
the synthesis of
catecholamines.
It
is rarely used in
the pre-operative management of phaeochromocytoma,
and long term in patients unsuitable for
surgery;
an
BNF 61
2.5.4 Alpha-adrenoceptor blocking drugs
113
2
Cardiovascular system