WHAT IS THIS MEDICINE AND WHAT IS IT USED FOR?
Revonto contains dantrolene sodium in a formulation for intravenous (IV)
use. Dantrolene works by blocking the release of calcium ions from the
sarcoplasmic reticulum inside skeletal muscle cells — the step that triggers
muscle contraction. By blocking this, dantrolene prevents and reverses
abnormal, sustained muscle contraction.
Its primary and most critical use is for malignant hyperthermia (MH) — a
rare but life-threatening genetic condition triggered by exposure to certain
anaesthetic agents (particularly succinylcholine and volatile anaesthetics such
as halothane, sevoflurane, and desflurane).
During malignant hyperthermia, skeletal muscles go into a massive,
uncontrolled contraction, generating enormous amounts of heat (hence
'hyperthermia' — extreme fever), depleting oxygen, and releasing potassium and
myoglobin — which can cause kidney failure. Without immediate dantrolene
treatment, MH can be rapidly fatal. Dantrolene is also used for neuroleptic
malignant syndrome (NMS) — a similar syndrome triggered by certain psychiatric
medicines — and for other forms of severe muscle rigidity. Oral dantrolene
capsules (not in this entry) are used for long-term management of muscle
spasticity in conditions such as cerebral palsy, multiple sclerosis, and spinal
cord injury.
3. HOW TO TAKE THIS MEDICINE
For malignant hyperthermia: immediately administer 2.5mg/kg intravenously
as a rapid bolus, then continue 2.5mg/kg every 5 to 10 minutes as needed, up to
a total dose of 10mg/kg. Response is usually seen within minutes. After the
acute episode, 1mg/kg IV every 6 hours for 24 to 48 hours to prevent
recurrence.
Each 20mg vial must be reconstituted with 60mL of sterile water for
injection. Six vials provide 120mg — the first bolus in a 48kg patient
(2.5mg/kg). For larger patients, many more vials will be needed — hospitals
stockpiling dantrolene for MH emergencies should hold 36 vials (720mg) minimum.
Dosing is by body weight and managed entirely by the anaesthetic and
resuscitation team.
Dantrolene vials contain mannitol as an excipient to improve solubility.
Reconstitution requires vigorous shaking with 60mL sterile water — the solution
may be slightly yellow or orange and may not be completely clear. Do not use
bacteriostatic water for injection (which contains benzyl alcohol). Use
immediately after reconstitution. This medicine is exclusively administered in
theatre, ICU, or by resuscitation teams — never in community settings.
⚠ PATIENT TIP: Revonto is an emergency medicine
used by anaesthetists and intensive care teams. If you have been told you have
a family history of malignant hyperthermia, carry a MH alert card or medical
bracelet and inform every anaesthetist, dentist, and surgeon before any procedure
under general anaesthesia. The anaesthetic team will choose safe,
non-triggering agents and ensure dantrolene is immediately available in the
operating theatre.
4. POSSIBLE SIDE EFFECTS
|
How Common? |
Side Effects |
|
During IV
Administration |
Muscle weakness
(intended effect), drowsiness, dizziness, nausea, phlebitis (vein irritation
at injection site — the formulation is alkaline) |
|
Less Common |
Confusion, respiratory
muscle weakness (requiring ventilatory support in high doses), pulmonary
oedema (fluid on the lungs — rare but reported) |
|
Serious — Monitor
Closely |
Hepatotoxicity —
primarily a concern with long-term oral dantrolene use rather than acute IV
use, but liver function should be monitored in prolonged treatment. Severe
respiratory depression in high doses. |
5. WHO SHOULD NOT TAKE THIS MEDICINE
IV dantrolene for malignant hyperthermia has no absolute
contraindications — it is a life-saving emergency treatment and should be given
regardless of pre-existing conditions when MH is confirmed or strongly
suspected. Relative caution in severe pre-existing hepatic disease (monitor
LFTs). Mannitol content — be aware in patients with renal failure (though this
is rarely a barrier in a true MH emergency).
⚠ MALIGNANT HYPERTHERMIA IS A MEDICAL EMERGENCY:
MH is rapidly fatal without prompt dantrolene treatment. Diagnosis is clinical
— rising temperature, muscle rigidity, tachycardia, and rising CO2. Do not
delay treatment pending laboratory confirmation. The anaesthetic team will
manage this — but awareness of the diagnosis is essential for all clinical
staff involved.
⚠ PREPARE SUFFICIENT VIALS IN ADVANCE: In a
large patient, many vials may be needed. Hospitals should pre-stock a minimum
of 36 vials (720mg) — some guidelines recommend up to 60 vials. Running out of
dantrolene during an MH crisis is a preventable catastrophe.
⚠ RECONSTITUTION: Each vial must be
reconstituted with exactly 60mL of sterile water for injection. The powder
dissolves slowly — vigorous shaking for up to 30 seconds may be required.
Multiple personnel may be needed to prepare vials rapidly in an emergency.
6. MEDICINES THAT INTERACT WITH THIS TREATMENT
Calcium channel blockers (particularly verapamil): combined IV use with
dantrolene is associated with cardiovascular collapse and hyperkalaemia — avoid
concurrent IV verapamil in MH treatment. Neuromuscular blocking agents: the
combination in MH management is handled by the anaesthetic team.
Oestrogen-containing preparations: may increase hepatotoxicity risk with
long-term oral dantrolene use.
7. HOW TO STORE THIS MEDICINE
Store below 30°C. Protect from light. Keep out of reach of children.
Reconstituted solution is not stable for extended periods — use immediately
after preparation.
8. PRESCRIPTION REQUIREMENT
|
Field |
Details |
|
Status |
Prescription Only
Medicine (POM) — Hospital emergency use only; managed by anaesthetic and
intensive care teams |
9. GUIDANCE FOR PATIENTS & CAREGIVERS
Revonto is an emergency medicine that will only ever be given to you in a
hospital by an anaesthetist or intensive care team — you will never manage this
medicine yourself. If you or a family member has been told you have a
susceptibility to malignant hyperthermia (or that a family member has had a MH
reaction), always carry a medical alert card and inform every anaesthetist,
dentist providing sedation, and surgeon before any procedure. MH is triggered
by specific anaesthetic agents — knowing in advance allows the anaesthetic team
to use safe alternatives.
10. PHARMACIST & PRESCRIBER NOTES
|
Field |
Details |
|
Clinical Dispensing
Notes |
IV dantrolene for
malignant hyperthermia emergency — hospital formulary item. Ensure adequate
stock: minimum 36 vials (720mg) recommended; local protocol may specify more.
Reconstitution: 60mL sterile water for injection per vial (not bacteriostatic
water); vigorous shaking required; solution may appear slightly yellow/orange
— acceptable. IV verapamil concurrent use: avoid — cardiovascular collapse
risk. Mannitol content: relevant in renal failure but MH is a life-saving
emergency. LFTs: relevant for prolonged oral dantrolene use rather than acute
IV. Staff education: reconstitution speed and vial volume — multiple staff
needed simultaneously in large patients. Post-crisis: oral dantrolene
continued for 24–72 hours (separate oral formulation). Ensure MHAUS
(Malignant Hyperthermia Association) hotline number is known to anaesthetic
team. |
11. FREQUENTLY ASKED QUESTIONS
Q: How does dantrolene treat malignant hyperthermia?
Dantrolene blocks the release of calcium inside muscle cells — the
trigger that makes muscles contract. By blocking this, it rapidly stops the
uncontrolled muscle contractions, allows the muscles to relax, and halts the
spiral of heat generation and organ damage. Given quickly, it reverses MH and
can be life-saving.
Q: Can I have a general anaesthetic if I have MH susceptibility?
Yes — with the right precautions. A trigger-free anaesthetic can be
safely administered using intravenous agents. Many thousands of operations are
performed each year safely in MH-susceptible patients. The key is ensuring the
anaesthetic team knows about the susceptibility in advance.
Q: Is dantrolene also used for anything else?
Oral dantrolene is used for long-term management of muscle spasticity in
conditions like cerebral palsy, multiple sclerosis, and spinal cord injury. The
IV form in this entry is used for emergency treatment of MH and neuroleptic
malignant syndrome (NMS) — a similar syndrome caused by certain psychiatric
medicines.
Q: What is an MH medical alert card and where do I get one?
An MH alert card identifies you as MH-susceptible and gives emergency
contact information for specialist advice. In the UK, these are available
through the British Malignant Hyperthermia Association (BMHA). Internationally,
the Malignant Hyperthermia Association of the United States (MHAUS) provides
similar resources. Ask your neurologist, anaesthetist, or genetic counsellor
how to obtain one in your country.