TOUGHENED SILVER NITRATE CAUSTICS IN MEDICINE
WARTS - VERRUCAE - CAUTERY - GRANULOMA
Traditional is often best! This is certainly true of silver nitrate as a medicinal product. Toughened Silver Nitrate is licensed by the Medicines Control Agency for use in the topical treatment of WARTS and VERRUCAE, for removing GRANULATION TISSUE, in CAUTERY, and as a general CAUSTIC. It offers several distinct advantages over other methods of treatment. Details are as follows.
General Information
Toughened Silver Nitrate - Silver Nitrate BP fused with Potassium Nitrate BP as a diluent - is well-established and proven as a general caustic, and competes very favourably with other modes of treament. For the destruction of warts and verrucae, application of Toughened Silver Nitrate caustic is almost completely painless, far more convenient than surgery or cryotherapy, and less hazardous than use of either more corrosive or systemically toxic chemicals such as nitric or chi oro acetic acid, salicylic acid, podophyllin or 5-fluorouracil. Furthermore silver nitrate is so effective that only very few applications are usually needed, in contrast to most of these other agents. Toughened Silver Nitrate proffers similar advantages with other caustic uses too. Being water-soluble, silver nitrate is easy to apply and to target to the desired area. Solutions soak into wart/verruca and granular tissue to some extent, and so are able to carry out their caustic action in situ, whereas healthy skin is hardly penetrated and so is left largely intact with only superficial staining. Silver nitrate is caustic due to its strong oxidising power.
Bray Health & Leisure supplies silver nitrate caustic in two easy-to-use presentations. Caustic Pencils consist of a handy colour-coded plastic case with a fused caustic point, complete with a removable cover, and are for single-patient use for the treatment of warts and verrucae. Many clinicians find Caustic Pencils useful also for some larger scale cautery applications such as umbilical 'stumps', however. Caustic Applicators have a small tip of Toughened Silver Nitrate fused onto one end of a 15-cm wooden handle, and are intended for clinical once-only use (and are not for sale to the general public). The latter are particularly useful for ear, nose and throat warts and delicate cautery operations. Both Caustic Pencils and Applicators are available in two strengths, the choice of which depends on the severity of treatment required.
Silver nitrate products must not be used for the treatment of genital warts. These are highly contagious and potentially malignant Reference should be made to the appropriate literature.
Method of Use
The following four-step process should be followed when using Caustic Pencils and Applicators:
Confine the area to be treated by encircling with petroleum jelly, ringed plaster or equivalent.
Slightly moisten the caustic tip by dipping (tip only) in (preferably distilled or deionised) water.
Apply the moistened tip to the tissue; two minutes' contact time is typically sufficient for a wart or verruca (NB The degree of caustic action depends on the actual quantity ofsilver nitrate applied, which in turn is governed by the length of time the moistened tip is left in contact with the tissue),
4. Cover the treated area well with a plaster or similar.
Excess silver nitrate can be neutralised with 0.9% or stronger saline, and washed away with water.
Contraindications, Warnings and Side-Effects
Since silver nitrate is a corrosive substance, it should be applied only to tissue to be treated, and care must be exercised both in confining it to the desired area by a suitable barrier such as petroleum jelly or ringed plaster, and in preventing any excess from wandering by covering as necessary afterwards. This is especially important during, for example, the treatment of infants' umbilical granulomas. Silver nitrate presents a particular hazard to the eyes, mouth and other sensitive areas.
Contact with silver nitrate with treated tissue and with healthy skin usually gives rise to distinctive black or brown stains. These are of deposited free metallic silver and as such are harmless once formed. Such stains are shed from skin by desquamation usually within a short time. Stain remover (q.v.) can be used on skin if really necessary, though this is recommended only for urgent cosmetic reasons. Silver nitrate similarly stains clothes and other inanimate surfaces with which it makes contact, and appropriate precautions should be taken to protect these from travelling caustic material.
Argyria, the accumulation of metallic silver in connective tissues, shows as a bluish-black discoloration of the skin, but whose early signs are often in the gums or eyes. Argyria arises from the application of excessive amounts of silver nitrate repeatedly for long periods, especially to mucous membranes and open wounds. Though not directly treatable it is regarded as a harmless cosmetic effect only. It may disappear with time.
Poisoning by ingestion is unlikely with the small quantities involved, but symptoms that do arise are due to the corrosive nature of silver nitrate, and may include pain in the mouth, sialorroea, diarrhoea, vomiting, convulsions and coma. Tissues and vomit will be stained black. See below for details.
Absorption of silver nitrate, mainly from burns or open wounds, in the presence of nitrate-reducing bacteria may result in methaemoglobinaemia.
Presentations
All are for single-patient use only
(Percentages are for Silver Nitrate BP content. Bray order codes are in parentheses)
(680) Caustic Pencils 95%
individually packed with accessories as the Avoca Complete Wart and Verruca Treatment Kit
(75) Caustic Pencils 40% packed in units of 12
(90) Caustic Applicators 75%
with larger fused caustic tip and broader handle than above, packed in units of 50
These products are made in the Bray Health & Leisure factory in Faringdon under licence nos. 4286/0004, 4286/0005 and 4286/0006. Bray also supply Silver Nitrate BP Crystals in jars of 25 grammes (code 452) and 250 grammes (code 451).
Storage
All silver nitrate caustic products must be stored well-sealed in a cool dry place away from light.
Stain Remover
NB: Neither Bray Health & Leisure nor any of its associate companies or bodies can accept any responsibility for any loss or damage to persons, animals or inanimate articles or surfaces resulting from the use of any of these stain remover formulations, whether that loss or damage be a result either of accident or use as intended and recommended.
Formulation 1
2% Hydrogen peroxide and 5% acetic acid in water, preferably adjusted to pH 3.5 to 3.7.
This Stain Remover may be used on the skin and on some robust surfaces such as ceramics, sinks, etc. (Always 'spot-test' an unimportant area first to establish that the method does not damage the surface). It should not be used on or even allowed to splash onto clothes and other acid- or peroxide-sensitive surfaces. Make up and use with extreme caution, since hydrogen peroxide is an oxidising agent. Keep well away from the face, and avoid contact with the eyes in particular. Accidental splashes and spillages must be mopped up and rinsed away immediately with copious amounts of tap water. If this mixture or hydrogen peroxide itself enters the eye rinse well with water. If swallowed drink lots of water. Seek medical advice as necessary. Make up as follows:
1. (By a pharmacist) Take 22 grammes of hydrogen peroxide '30 volume' (9%) and S grammes of glacial acetic acid and make up to about 80 millilitres with water. Using strong sodium hydroxide solution adjust the pH to about 3.6. Make up to a total volume of 100 millilitres and mix thoroughly. Supply in a dark poison bottle and label correctly. It should be used within one month. (Note: Strengths of hydrogen peroxide other than 9% may be used as masters for dilutions provided appropriate adjustments are made to the quantities taken, and that the strength of hydrogen peroxide in the final product is 2%).
2. (By the customer, with extreme care;) Obtain hydrogen peroxide - '30 volume' (9%) from your local pharmacist. Ensure that it is of the correct strength - '30 volume' (9%). Using a standard kitchen measuring jug dilute one part of this 30 volume hydrogen peroxide with four parts of household vinegar (e.g. 50 mls with 200 mls) and mix well. Use immediately.
Taking care to confine the solution just to the area to be treated, rub gently onto the skin for up to two minutes, then rinse immediately with lots of tap water. Robust inanimate surfaces may be soaked for
longer if required, then rinsed. Dispose of unused solution down the sink, rinsing away with copious amounts of water.
Formulation 2
8% Citric acid and 8% thiourea in water, freshly made up and used immediately.
Formulation 2 should not be used on the human body. It may be effective on a wider range than above of inanimate surfaces and objects including clothes, though all materials should be carefully spot-tested' first. Protective gloves and goggles should be used as appropriate. Avoid breathing fumes and ventilate the area well. Other precautions and first aid measures should be as above with formulation 1.
Treatment for Silver Nitrate Poisoning by Ingestion
Begin without delay. Give 1 % sodium chloride solution as stomach lavage then empty stomach by aspiration, repeatedly. After lavage give a purgative such as 30 grammes sodium sulphate in 250 ml of water. Demulcents like egg-white, milk or liquid paraffin may be administered, with pethidine or morphine if necessary. Pay close attention to renal function and fluid balance.
Revised August 1997
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