Monograph: |
Phenolphthalein
A white or yellowish-white, odourless or almost odourless.
crystalline or amorphous powder.
Practically insoluble in water; soluble I in 15 of alcohol and
I in 100 of ether; dissolves in dilute solutions of alkali hy-
droxides. and in hot solutions of alkali carbonates, forming a
red solution.
Adverse Effects
Hypersensitivity reactions, usually as skin rashes or erup-
tions. have occurred with phenolphthalein. Abdominal dis-
comfort such as cramps or colic may occasionally occur.
Prolonged use or overdosage can result in diarrhoea with ex-
cessive loss of water and electrolytes, particularly potassium:
there is also the possibility of developing an atonic non-func-
tioning colon.
Phenolphthalein may cause pink discoloration of alkaline
urine.
Tumours have occurred in rats and mice given very high dos-
es of phenolphthalein: there docs not appear to be evidence of
carcinogenicity in humans, but phenolphthalein-containing
products have been withdrawn in a number of countries be-
cause of concerns about long-term safety.
Effects on the skin. Reports of skin reactions associated
with phenolphthalein include fixed drug eruptions. ery-
thema multiforme reactions and toxic epidermal necrolysis.
Overdosage. The most likely consequence bf phenol-
phthalein overdosage is excessive purgation, which may re-
quire fluid and electrolyte replacement. However, a possible
association with acute pancreatitis occurred in a 34-year-old
man who inadvertently ingested phenolphthalein 2 g. There
was complete recovery with no sequelae from the pancreati-
tis. Widespread organ failure with disseminated intravascu-
lar coagulation, massive liver damage, pulmonary oedema,
renal failure, and myocardial damage in a second patient
were attributed to self-poisoning with an unknown quantity of
phenolphthalein-containing laxative, although the diagnosis
was problematic. The patient died despite intensive support.
Precautions
As for Bisacodyl.
Pharmacokinetics
Up to 15% of phenolphthalein given by mouth is subsequent-
ly excreted in the urine. Enterohepatic circulation occurs and
the glucuronide is excreted in the bile. Elimination may take
several days.
UMS and Administration
Phenolphthalein is a diphenylmethane stimulant laxative
which has been used for the treatment of constipation
and for bowel evacuation before investigational pro-
cedures or surgery. It usually has an effect within 4 to 8 hours
following administration by mouth.
It is usually administered in pills or tablets, and is also avail
able as an emulsion with liquid paraffin. It is usually given in
a dose of 30 to 200 mg taken at bedtime; doses of 270 mg
daily should not be exceeded. A dose of 260 mg has been
used in regimens for bowel evacuation.
Yellow phenolphthalein. an impure form. is used similarly.
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