DIGOXIN
Digoxintoxicity is common in the elderly because of decreased
renal elimination and reduced apparent volume of distribution.
Confusion, nausea and vomiting, altered vision and an acute
abdominal syndrome resembling mesenteric artery obstruction
are all more common features of digoxintoxicity in the elderly
than in the young. Hypokalaemia due to decreased potassium
intake (potassium-rich foods are often expensive), faulty homeo-
static mechanisms resulting in increased renal loss and the con-
comitant use of diuretics is more common in the elderly, and is
a contributory factor in some patients. Digoxinis sometimes
prescribed when there is no indication for it (e.g. for an irregu-
lar pulse which is due to multiple ectopic beats rather than
atrial fibrillation). At other times, the indications for initiation of
treatment are correct but the situation is never reviewed. In one
series of geriatric patients on digoxin, the drug was withdrawn
in 78% of cases without detrimental effects.
DIURETICS
Diuretics are more likely to cause adverse effects (e.g. postural
hypotension, glucose intolerance and electrolyte disturbances)
in elderly patients. Too vigorous a diuresis may result in urin-
ary retention in an old man with an enlarged prostate, and
necessitate bladder catheterization with its attendant risks.
Brisk diuresis in patients with mental impairment or reduced
mobility can result in incontinence. For many patients, a thia-
zide diuretic, such as bendroflumethiazide, is adequate. Loop
diuretics, such as furosemide, should be used in acute heart
failure or in the lowest effective dose for maintenance treatment
of chronic heart failure. Clinically important hypokalaemia is
uncommon with low doses of diuretics, but plasma potassium
should be checked after starting treatment. If clinically important
hypokalaemia develops, a thiazide plus potassium-retaining
diuretic (amilorideortriamterene) can be considered, but there
is a risk of hyperkalaemia due to renal impairment, especially
if an ACE inhibitor and/or angiotensin receptor antagonist
and aldosterone antagonist are given together with the diuretic
for hypertension or heart failure. Thiazide-induced gout and
glucose intolerance are important side effects.
ISCHAEMIC HEART DISEASE
This is covered in Chapter 29.
ANGIOTENSIN CONVERTING ENZYME INHIBITORS
(ACEI) AND ANGIOTENSIN RECEPTOR BLOCKERS (ARB)
These drugs plays an important part in the treatment of chronic
heart failure, as well as hypertension (see Chapters 28 and 31),
and are effective and usually well tolerated in the elderly.
However, hypotension, hyperkalaemia and renal failure are
more common in this age group. The possibility of atheroma-
tous renal artery stenosis should be borne in mind and serum
creatinine levels checked before and after starting treatment.
Potassium-retaining diuretics should be co-administered only
with extreme caution, because of the reduced GFR and plasma
potassium levels monitored. Despite differences in their phar-
macology, ACEI and ARB appear similar in efficacy, but ARB
do not cause the dry cough that is common with ACEI. The
EFFECT OFDRUGS ONSOMEMAJORORGANSYSTEMS INTHEELDERLY 59question of whether co-administration of ACEI with ARB has
much to add remains controversial; in elderly patients with
reduced GFR, the safety of such combined therapy is an impor-
tant consideration.ORAL HYPOGLYCAEMIC AGENTSDiabetes is common in the elderly and many patients are
treated with oral hypoglycaemic drugs (see Chapter 37). It is
best for elderly patients to be managed with diet if at all possi-
ble. In obese elderly diabetics who remain symptomatic on
diet,metforminshould be considered, but coexisting renal,
heart or lung disease may preclude its use. Short-acting
sulphonylureas (e.g. gliclazide) are preferred to longer-acting
drugs because of the risk of hypoglycaemia: chlorpropamide
(half-life 36 hours) can cause prolonged hypoglycaemia and is
specifically contraindicated in this age group, glibenclamide
should also be avoided. Insulinmay be needed, but impaired
visual and cognitive skills must be considered on an individual
basis, and the potential need for dose reduction with advanc-
ing age and progressive renal impairment taken into account.ANTIBIOTICSThe decline in renal function must be borne in mind when an
antibiotic that is renally excreted is prescribed, especially if it is
nephrotoxic (e.g. an aminoglycoside or tetracycline). Appendix 3
of the British National Formulary is an invaluable practical guide.
Over-prescription of antibiotics is a threat to all age groups,
but especially in the elderly. Broad-spectrum drugs including
cephalosporins and other beta-lactams, and fluoroquinones are
common precursors of Clostridium difficileinfection which has a
high mortality rate in the elderly. Amoxicillinis the most com-
mon cause of drug rash in the elderly. Flucloxacillin induced
cholestatic jaundice and hepatitis is more common in the elderly.Case history
An 80-year-old retired publican was referred with ‘congest-
ive cardiac failure and acute retention of urine’. His wife
said his symptoms of ankle swelling and breathlessness had
gradually increased over a period of six months despite the
GP doubling the water tablet (co-amilozide) which he was
taking for high blood pressure. Over the previous week he
had become mildly confused and restless at night, for
which the GP had prescribed chlorpromazine. His other
medication included ketoprofen for osteoarthritis and fre-
quent magnesium trisilicate mixture for indigestion. He
had been getting up nearly ten times most nights for a year
to pass urine. During the day, he frequently passed small
amounts of urine. Over the previous 24 hours, he had been
unable to pass urine. His wife thought most of his problems
were due to the fact that he drank two pints of beer each
day since his retirement seven years previously.
On physical examination he was clinically anaemic, but
not cyanosed. Findings were consistent with congestive
cardiac failure. His bladder was palpable up to his umbili-
cus. Rectal examination revealed an enlarged, symmetrical
prostate and black tarry faeces. Fundoscopy revealed a
grade II hypertensive retinopathy.