METHYLTHIONINIUM CHLORIDE INJECTION USP 1% W/V
Active substance(s): METHYLTHIONINIUM CHLORIDE
NAME OF THE MEDICINAL PRODUCT
Methylthioninium Chloride Injection USP 1% w/v
QUALITATIVE AND QUANTITATIVE COMPOSITION
Methylthioninium Chloride USP 1% w/v
Sterile Aqueous Injection
Drug induced methaemoglobinaemia
Posology and Method of administration
Inject Methylthioninium Chloride very slowly over several minutes.
Route of administration: Intravenous Injection.
Adults and the elderly
0.1 - 0.2ml/kg body weight.
Not to be administered by intra-spinal injection or subcutaneous injection.
Glucose-6-phosphate dehydrogenase deficiency and sodium nitrite induced
Special Warnings and Special Precautions for Use
Methylthioninium Chloride must be injected very slowly over a period of
several minutes to prevent high local concentrations of the compound from
producing additional methaemoglobin. Do not exceed the recommended
dosage. Severe renal impairment and aniline-induced methaemaglobinaemia
as his may precipitate Heinz body formation and haemolytic anaemia.
Interaction with other medicinal products and other forms of interaction
Adverse CNS effects including confusion, disorientation, agitation, expressive
aphasia, altered muscle tone in limbs, hypoxia, ocular symptoms, and depressed level
of consciousness have been reported following intravenous infusion of
methylthioninium chloride for parathyroid surgery.The use of methylthioninium for
localisation in parathyroid surgery falls outside the approved indications (see section
4.1). Toxicity has occurred with doses of 3 mg/kg and in one case adverse CNS
effects were reported after a dose of 1.75 mg/kg in a woman weighing 115 kg. The
affected patients had been treated with serotonergic drugs. Methylthioninium should
preferably be avoided in patients receiving drugs that enhance serotonergic
transmission including SSRIs, bupropion, buspirone, clomipramine, mirtazapine, and
venlafaxine. If the intravenous use of methylthioninium cannot be avoided in patients
treated with serotonergic drugs, the lowest possible dose should be chosen and the
patient observed closely for CNS effects for up to 4 hours after administration.
Pregnancy and Lactation
As with all drugs during Pregnancy, care should be taken in assessing the risk
to benefit ratio.
Effects on Ability to Drive and Use Machines
Large intravenous doses of Methylthioninium Chloride produce nausea,
abdominal and precordial pain, dizziness, headache, profuse sweating, mental
confusion and the formation of methaemoglobin, also hypertension.
The symptoms of overdose are as above. The patient should be maintained
under observation and appropriate supportive measures taken as necessary.
In-vivo, in low concentration, Methylthioninium Chloride speeds up the
conversion of methaemoglobin to haemoglobin.
After i.v. administration Methylthioninium Chloride is rapidly taken up by the
tissues. It is also well absorbed by the oral route. The majority of the dose is
excreted in the urine, usually in the form of leuco Methylthioninium Chloride.
Preclinical Safety Data
There are no additional pre-clinical data of relevance to the prescriber.
List of excipients
Water for Injections BP to 100%
Unopened ampoules: 5 years (60 Months).
Special Precautions for Storage
Store below 25°C
Nature and Contents of Container
Clear colourless neutral glass ampoules containing 10ml of product. Packs of
10 ampoules in suitable cartons are available.
Instructions for Use/Handling
Use immediately on opening. Inject very slowly over several minutes.
Administer through a sterile 0.45 micron Filter.
MARKETING AUTHORISATION HOLDER
Martindale Pharmaceuticals Limited.
MARKETING AUTHORISATION NUMBER(S)
Methylthioninium Chloride Injection USP 1%w/v
DATE OF FIRST AUTHORISATION/RENEWAL OF THE
DATE OF REVISION OF THE TEXT
Source: Medicines and Healthcare Products Regulatory Agency
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