Monograph: |
Phenylmercuric Nitrate
A mixture of phenylmercuric nitrate and phenylmercuric hy-
droxide. A white or pale yellow, crystalline powder. Slightly
or very slightly soluble in water and in alcohol: slightly solu-
ble in hot water and in glycerol: more soluble in the presence
of nitric acid or alkali hydroxides; dissolves in fatty oils. A
saturated solution in water is acid to litmus. Store in airtight
containers. Protect from light.
Incompatibilities. The activity of phenylmercuric salts may
be reduced by interaction with compounds such as kaolin.
magnesium trisilicate, starch, and talc. Disodium edetate
and sodium thiosulphate can also produce inactivation. Sodi-
um metabisulphite can lead to precipitation, or chemical de-
stnlction, but it can also produce increased activity. Other
incompatibilities include bromides, iodides (chlorides to a
lesser extent), metals, and ammonia and its salts. There can
be adsorption onto rubber and some plastics although sorp-
tion by low density polyethylene can be inhibited by phos-
phate ions. Some filters, though not membrane filters, used
for sterilisation removed considerable amounts of phenylmer-
curic nitrate from solution. The pH may also affect activity.
Adverse Effects and Precautions
While the adverse effects of inorganic mercury
should be taken into account when consid-
ering the adverse effects of phenylmercuric com-
pounds. there is little evidence of systemic toxicity
arising from their use. They are irritant to the skin
and may give rise to erythema and blistering. Hyper-
sensitivity reactions have been reported. Topical ap-
plication to eyes has been associated with
mercurialentis and atypical band keratopathy; pro-
longed use of eye drops containing phenylmercuric
preservatives is not recommended.
Effects on the eyes. References to primary atypical band
keratopathy and pigmentation of the anterior capsule of the
lens (mercurialentis) associated with the prolonged use of eye
drops containing phenylmercuric preservative.
Uses
Phenylmercuric salts have antibacterial and antifun-
gal properties. They are primarily bacteriostatic
compounds although they also have a slow bacteri-
cidal action. Their activity has been reported to be
pH dependent.
Phenylmercuric compounds are used as preserva-
tives in cosmetic, ophthalmic, or pharmaceutical
preparations and as antiseptics. They have also been
used as spermicides.
When employed as a preservative in eye drops, a
concentration of 0.002% is usually used; in injection
solutions the concentration is 0.001%.
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