C H A P T E R 2 2
Psychotherapeutic agents
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severe hyponatraemia may occur.
(Hyponatraemia
leads to lithium retention and toxicity.) Pregnancy and
breastfeeding are also contraindications
because of the
potential for adverse effects on the fetus or neonate;
breastfeeding should be discontinued while using lithium
and women of childbearing age should be advised to use
birth control while taking this drug. Caution should be
used in any condition
that could alter sodium levels
,
such as protracted diarrhoea or excessive sweating; with
suicidal or impulsive individuals; and in people who
have infection with fever,
which could be exacerbated
by the toxic effects of the drug.
Adverse effects
The adverse effects associated with lithium are directly
related to serum levels of the drug.
•
Serum levels of less than 1.5 mEq/L
: CNS problems,
including lethargy, slurred speech, muscle weakness
and fine tremor; polyuria, which relates to renal
toxicity; and beginning of gastric toxicity, with
nausea, vomiting and diarrhoea.
•
Serum levels of 1.5 to 2 mEq/L
: Intensification of all
of the foregoing reactions, with ECG changes.
•
Serum levels of 2 to 2.5 mEq/L
: Possible progression
of CNS effects to ataxia, clonic movements,
hyperreflexia and seizures; possible CV effects such
as severe ECG changes and hypotension; large output
of dilute urine secondary to renal toxicity; fatalities
secondary to pulmonary toxicity.
•
Serum levels greater than 2.5 mEq/L
: Complex
multiorgan toxicity, with a significant risk of death.
Clinically important drug–drug interactions
Some drug–drug combinations should be avoided. A
lithium–haloperidol combination may result in an enceph-
alopathic syndrome, consisting of weakness, lethargy,
confusion, tremors, extrapyramidal symptoms, leucocy-
tosis and irreversible brain damage (see Box 22.6).
If lithium is given with carbamazepine, increased
CNS toxicity may occur and a lithium–iodide salt com-
bination results in an increased risk of hypothyroidism.
People who receive either of these combinations should
be monitored carefully. In addition, a thiazide diuretic–
lithium combination increases the risk of lithium toxicity
because of the loss of sodium and increased retention of
lithium. If this combination is used, the dose of lithium
should be decreased and the person should be monitored
closely.
In the following instances, the serum lithium level
should be monitored closely and appropriate dose
adjustments made. With the combination of lithium and
some urine-alkalinising drugs, including antacids, there
is a possibility of decreased effectiveness of lithium. If
lithium is combined with indomethacin or with some
nonsteroidal anti-inflammatory drugs, higher plasma
TABLE 22.2
DRUGS IN FOCUS Antimanic drugs
Drug name
Dosage/route
Usual indications
aripiprazole (Abilify)
30 mg/day PO
Treatment of acute manic and mixed
episodes of bipolar disorders
lamotrigine (Lamictal)
25 mg/day PO up to 200 mg/day
Long-term maintenance of people with
bipolar disorders; decreases occurrence
of acute mood episodes
lithium salts (Lithicarb,
Quilonum SR)
500–1000 mg/day based on serum lithium
levels
Treatment of manic episodes of manic-
depressive or bipolar illness; maintenance
therapy to prevent or diminish the
frequency and intensity of future manic
episodes; currently being studied for
improvement of neutrophil counts in
people with cancer chemotherapy-
induced neutropenia and as prophylaxis
of cluster headaches and migraine
headaches; not recommended for
children <12 years
olanzapine (Zyprexa,
Zyprexa Zydis)
10 mg/day PO; range 5–20 mg/day
Management of acute manic episodes
associated with bipolar disorder, in
combination with lithium or valproate,
or as monotherapy
quetiapine (Seroquel)
50 mg PO b.d., titrate to a maximum
800 mg/day
Adjunct or monotherapy for the treatment
of manic episodes associated with
bipolar disorder
ziprasidone (Zeldox)
40 mg PO b.d. with food; maximum 80 mg b.d.
Treatment of acute manic and mixed
episodes of bipolar disorders
