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PENTHROX is a brand name for Methoxyflurane. The medicine, its uses, side effects and dosage are the same regardless of brand.
Used for: Emergency relief of moderate to severe pain in conscious adult patients with trauma and associated pain.
Verbatim from this product's MHRA label. Tap a section to expand.
PENTHROX should be self-administered under supervision of a person trained in its administration, using the hand held PENTHROX Inhaler. It is inhaled through the PENTHROX inhaler. The intended purpose of the Penthrox inhaler is to administer the analgesic drug Penthrox (methoxyflurane).
Penthrox is poured into the device and as a patient breathes in through the device the patient inhales the Penthrox vapour. 2). Posology Adults One bottle of 3 ml PENTHROX as a single dose, administered using the device provided. A second bottle should only be used where needed.
4). The following administration schedule is recommended: no more than 6 ml in a single day, administration on consecutive days is not recommended, and the total dose to a patient in a week should not exceed 15 ml. Onset of pain relief is rapid and occurs after 6–10 inhalations.
Patients should be instructed to inhale intermittently to achieve adequate analgesia. Patients are able to assess their own level of pain and titrate the amount of PENTHROX inhaled for adequate pain control. Continuous inhalation of a bottle containing 3 ml provides analgesic relief for up to 25-30 minutes.
Intermittent inhalation may provide longer analgesic relief. 4). Renal impairment Methoxyflurane may cause renal failure if the recommended dose is exceeded. 4). 4). Paediatric population PENTHROX should not be used in children and adolescents under 18 years.
Method of Administration For inhalation use. Instructions on the preparation of the PENTHROX Inhaler and correct administration are provided in the Figures below. Before use, check for foreign objects, broken or deteriorated parts. Do not use this device if any are identified.
1 Ensure the Activated Carbon (AC) Chamber is inserted into the dilutor hole on the top of the PENTHROX Inhaler. 2 Remove the cap of the bottle by hand. Alternatively, use the base of the PENTHROX Inhaler to loosen the cap with a ½ turn.
Separate the Inhaler from the bottle and remove the cap by hand. 3 Tilt the PENTHROX Inhaler to a 45° angle and pour the total contents of one PENTHROX bottle into the base of the Inhaler whilst rotating. 4 Place wrist loop over patient’s wrist.
Patient inhales and exhales PENTHROX through the mouthpiece to obtain analgesia. First few breaths should be gentle and then breathe normally through Inhaler. 5 Patient exhales into the PENTHROX Inhaler. The exhaled vapour passes through the AC Chamber to adsorb any exhaled methoxyflurane.
Summary of safety profile The common non-serious reactions are CNS type reactions such as dizziness, and somnolence, and are generally easily reversible. Tabulated list of adverse reactions ‘Serious dose-related nephrotoxicity has only been associated with methoxyflurane when used in large doses over prolonged periods during general anaesthesia.
Methoxyflurane is therefore no longer used for anaesthesia. 4 under renal disease. ’ The following table consists of adverse drug reactions: - Observed in PENTHROX clinical studies in analgesia - Observed with analgesic use of methoxyflurane following post-marketing experience - Adverse reactions linked to methoxyflurane use in analgesic found in post marketing experience and in scientific literature The following frequencies are the basis for assessing undesirable effects: Very common (≥1/10) Common (≥1/100 to <1/10); Uncommon (≥1/1,000 to <1/100); Rare (≥1/10,000 to <1/1000); Very rare (<1/10,000); and Not known (cannot be estimated from the available data).
MedDRA System Organ Class Very common ≥1/10 Common ≥1/100 to <1/10 Uncommon ≥1/1,000 to <1/100 Not known Immune system disorders Hypersensitivity^ Metabolism and nutrition disorders Increased appetite Psychiatric disorders Euphoric mood Anxiety Depression Disturbance in attention Inappropriate affect Verbigeration Affect lability^, Agitation^, Confusional state^, Dissociation^, Restlessness^.
Nervous system disorders Dizziness Headache Somnolence Dysgeusia Amnesia Dysarthria Paraesthesia Peripheral sensory neuropathy Altered state of consciousness^, Nystagmus^ Eye disorders Vision impairment Vascular disorders Flushing Hypertension Hypotension Respiratory, thoracic and mediastinal disorders Cough Choking^, Hypoxia^.
Respiratory depression^. Gastrointestinal disorders Nausea Dry mouth Oral discomfort Oral pruritus Salivary hypersecretion Vomiting Hepatobiliary disorders Hepatic failure*, Hepatitis*, Jaundice^, Liver injury^. Skin and subcutaneous tissue disorders Hyperhidrosis Renal and urinary disorders Renal failure^ General disorders and administration site conditions Feeling drunk Fatigue Feeling abnormal Chills Feeling of relaxation Investigations Hepatic enzyme increased^, Blood urea increased Blood uric acid increased^, Blood creatinine increased^.
Renal disease To ensure the safe use of PENTHROX as an analgesic the following precautions should be observed. - Use the lowest effective dose to control pain - Use with caution in the elderly or other patients with known risk factors for renal disease.
- Use with caution in patients diagnosed with clinical conditions which may pre-dispose to renal injury. Methoxyflurane causes significant nephrotoxicity at high doses. Nephrotoxicity is thought to be associated with inorganic fluoride ions, a metabolic breakdown product.
When administered as instructed for the analgesic indication, a single dose of 3 ml methoxyflurane produces serum levels of inorganic fluoride ions below 10 micromol/l. In the past when used as an anaesthetic agent, methoxyflurane at high doses caused significant nephrotoxicity, which was determined to occur at serum levels of inorganic fluoride ions greater than 40 micromol/l.
Nephrotoxicity is also related to the rate of metabolism. 5). Liver disease Methoxyflurane is metabolised in the liver, therefore increased exposures in patients with hepatic impairment can cause toxicity. 3). 5). It has been reported that previous exposure to halogenated hydrocarbon anaesthetics (including methoxyflurane when used in the past as an anaesthetic agent), especially if the interval is less than 3 months, may increase the potential for hepatic injury.
Cautious clinical judgement should be exercised when PENTHROX is to be used more frequently than on one occasion every 3 months. Cardiovascular system depression / use in elderly Potential effects on blood pressure and heart rate are known class-effects of high dose methoxyflurane used in anaesthesia and other anaesthetics.
They do not appear to be significant at the analgesic doses. There is no particular pattern to the patients’ systolic blood pressure levels after methoxyflurane administration as an analgesic across age groups. However, as the risk may potentially be increased for older people with hypotension and bradycardia, caution should be exercised in the elderly due to possible reduction in blood pressure.
Use as an anaesthetic agent. 1. Malignant hyperthermia: patients who are known to be or genetically susceptible to malignant hyperthermia. Patients or patients with a known family history of severe adverse reactions after being administered with inhaled anaesthetics.
Patients who have a history of showing signs of liver damage after previous methoxyflurane use or halogenated hydrocarbon anaesthesia. Clinically significant renal impairment. Altered level of consciousness due to any cause including head injury, drugs, or alcohol.
Clinically evident cardiovascular instability. Clinically evident respiratory depression.
Not medical advice. Always read the patient information leaflet and follow your prescriber or pharmacist.
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6 If stronger analgesia is required, patient can cover dilutor hole on the AC chamber with finger during use. 7 If further pain relief is required, after the first bottle has been used use a second bottle if available. Alternatively use a second bottle from a new combination pack.
Use in the same way as the first bottle in step 2 and 3. No need to remove the AC Chamber. Put used bottle into the plastic bag provided. 8 Patient should be instructed to inhale intermittently to achieve adequate analgesia. Continuous inhalation will reduce duration of use.
Minimum dose to achieve analgesia should be administered. 9 Replace cap onto PENTHROX bottle. 6). The person trained in administering PENTHROX must provide and explain the Package Leaflet to the patient
* *isolated post-marketing reports that have been observed with analgesic use of methoxyflurane ^Other events linked to methoxyflurane use in analgesia found in post marketing experience and in scientific literature Reporting of suspected adverse reactions Reporting suspected adverse reactions after authorisation of the medicinal product is important.
It allows continued monitoring of the benefit/risk balance of the medicinal product. uk/yellowcard.
Central nervous system (CNS) effects Secondary pharmacodynamic effects including potential CNS effects such as sedation, euphoria, amnesia, ability to concentrate, altered sensorimotor co-ordination and change in mood are also known class-effects.
Self-administration of methoxyflurane in analgesic doses will be limited by occurrence of CNS effects, such as sedation. Whilst the possibility of CNS effects may be seen as risk factor for potential abuse, reports are very rare in post marketing use.
8). Respiration should be monitored due to the risk for respiratory depression and hypoxia. 2) and the duration of pain relief, PENTHROX is not appropriate for providing relief of break- through pain/exacerbations in chronic pain conditions.
PENTHROX is also not appropriate for relief of trauma related pain in closely repeated episodes for the same patient. Butylated hydroxytoluene PENTHROX contains the excipient, butylated hydroxytoluene (E321), a stabiliser. g. contact dermatitis), or irritation to the eyes and mucous membranes.
1. Occupational exposure Healthcare professionals who are regularly exposed to patients using PENTHROX inhalers should be aware of any relevant occupational health and safety guidelines for the use of inhalational agents. To reduce occupational exposure to methoxyflurane, the PENTHROX inhaler should always be used with the Activated Carbon (AC) Chamber which adsorbs exhaled methoxyflurane.
Multiple use of PENTHROX Inhaler without the AC Chamber creates additional risk. Elevation of liver enzymes, blood urea nitrogen and serum uric acid have been reported in exposed maternity ward staff in delivery wards when methoxyflurane was used in the past in obstetric patients at the time of labour and delivery.
There have been reports of non-serious and transient reactions such as dizziness, headache, nausea or malaise, and reports of hypersensitivity reactions to methoxyflurane or other ingredients in healthcare professionals exposed to Penthrox.
Measurements of exposure levels to methoxyflurane in hospital staff showed levels significantly lower than those associated with nephrotoxicity.