782 Musculoskeletal drugs
Reactions may be
common
, uncommon,
life-threatening
, or
commonandlife-threatening.
Children:
Initially, 0.5 mg/kg PO b.i.d.,
increasedtot.i.d.,thenq.i.d.Dosageincreased,
p.r.n., by 0.5 mg/kg daily to 3 mg/kg b.i.d. to
q.i.d. Maximumdosage is 100 mg q.i.d.
➤
Management of malignant hyperthermia
crisis—
Adults and children:
1 mg/kg IV initially;
dose repeated, p.r.n., up to cumulative
dosage of 10 mg/kg.
➤
Prevention or attenuation of malignant
hyperthermia crisis in susceptible individuals
who require surgery—
Adults:
4–8 mg/kg PO daily in three to
four divided doses for 1–2 days before
procedure. Final dose administered 3–4
hours before procedure.
➤
Prevention of recurrence of malignant
hyperthermia crisis—
Adults:
4–8 mg/kg daily PO in four divided
doses for up to 3 days after hyperthermic
crisis.
IV administration
• Give as soon as malignant hyperthermia
reaction is recognised.
• Reconstitute each vial by adding 60 mL
of sterile water for injection and shaking
vial until clear. Do not use a diluent that
contains a bacteriostatic agent.
• Watch for irritation and infiltration;
extravasation can cause tissue damage and
necrosis.
• Protect contents from light and usewithin
6 hours.
Action
Acts directly on skeletal muscle to interfere
with intracellular calcium movement by
decreasing excitation and contraction
coupling and reducing muscle strength.
Route Onset
Peak
Duration
PO Unknown 5 hrs
Unknown
IV
Unknown Unknown Unknown
Adverse reactions
CNS:
drowsiness, dizziness,
fever, light-
headedness,
malaise, fatigue,
headache,
confusion, nervousness, insomnia,
seizures.
CV:
tachycardia, erratic blood pressure.
ENT:
speech disturbance.
Eye:
excessive lacrimation, diplopia, visual
disturbances.
GI:
anorexia, constipation, cramping, dys
phagia, metallic taste, severe diarrhoea, GI
bleeding.
GU:
urinary frequency, haematuria, incontin
ence, nocturia, dysuria, crystalluria, difficult
erection, urine retention, increased urea
level.
Hepatic:
hepatitis
, increased ALT, AST,
alkaline phosphatase, LDH and total serum
bilirubin levels.
Musculoskeletal:
myalgia, back pain,
muscle weakness
.
Respiratory:
pleuraleffusionwithpericarditis.
Skin:
eczematouseruption,pruritus,urticaria,
abnormal hair growth, sweating.
Other:
chills.
Interactions
Drug-drug.
CNSdepressants:
Increased CNS
depression. Avoid use together.
Oestrogens:
Possible increased risk of
hepatotoxicity. Use together cautiously.
Verapamil:
Possible CV collapse with IV
verapamil. Stop verapamil before administ
ering IV dantrolene.
Drug-lifestyle.
Alcohol use:
Increased CNS
depression. Caution person to avoid alcohol
use.
Sunexposure:
Photosensitivity and increased
risk of sunburn. Advise person to take
precautions and to avoid excessive sunlight.
Contraindications
Contraindicated in individuals when
spasticity is used tomaintainmotor function
orforspasms inrheumaticdisorders; inthose
with uppermotor neuron disorders or active
hepatic disease; and in women who are
breastfeeding.
care considerations
• Use cautiously in individuals with severely
impaired cardiac or pulmonary function or
pre-existing hepatic disease, inwomen and
in individuals older than 35 years.
