Dantrolene Sodium; Uses, Dosage, Side Effects, Interactions

Mechanism of Action of Dantrolene Sodium

Dantrolene depresses excitation-contraction coupling in skeletal muscle by binding to the ryanodine receptor and decreasing intracellular calcium concentration. Ryanodine receptors mediate the release of calcium from the sarcoplasmic reticulum, an essential step in muscle contraction. Dantrolene is classified as a direct-acting skeletal muscle relaxant. It is currently the only specific and effective treatment for malignant hyperthermia. In isolated nerve-muscle preparation, Dantrium has been shown to produce relaxation by affecting the contractile response of the muscle at a site beyond the myoneural junction. In skeletal muscle, Dantrium dissociates excitation-contraction coupling, probably by interfering with the release of Ca²⁺ from the sarcoplasmic reticulum. In the anesthetic-induced malignant hyperthermia syndrome, evidence points to an intrinsic abnormality of skeletal muscle tissue. In selected humans, it has been postulated that “triggering agents” (e.g., general anesthetics and depolarizing neuromuscular blocking agents) produce a change within the cell which results in an elevated myoplasmic calcium. This elevated myoplasmic calcium activates acute cellular catabolic processes that cascade to the malignant hyperthermia crisis. It is hypothesized that the addition of Dantrium to the “triggered” malignant hyperthermic muscle cell reestablishes a normal level of ionized calcium in the myoplasm.

Indications of Dantrolene Sodium

• Chronic spasticity
• Malignant hyperthermia
• Spasticity
• Used to treat muscle tightness
• Cramping (spasms) caused by certain nerve disorders such as spinal cord injury,
• Stroke, 
• Cerebral palsy,
• Multiple sclerosis.
• Rigidity
• Cervical spondylosis
• Postoperative sequelae (including from a cerebrospinal tumour)
• Sequelae to trauma (e.g. spinal trauma or head injury)
• Amyotrophic lateral sclerosis
• Spinocerebellar degeneration
• Spinal vascular diseases and other encephalomyelopathies
• Cervical syndrome, periarthritis of the shoulder, and lumbago
• Skeletal muscle relaxation
• Relaxation of hypertonic skeletal muscles
• Improves intramuscular blood flow
• Suppression of spinal reflex potentials
• Reduction of muscle spindle sensitivity via motor neurons
• Vasodilatation and augmentation of blood flow
• Analgesic action and inhibition of the pain reflex in the spinal cord
• It works by relaxing the muscles. 
• Dantrolene helps reduce muscle pain and stiffness, improves your ability to move around, and lets you do more of your daily activities.
• For use, along with appropriate supportive measures, for the management of the fulminant hypermetabolism of skeletal muscle characteristic of malignant hyperthermia crises in patients of all ages. Also used preoperatively, and sometimes postoperatively, to prevent or attenuate the development of clinical and laboratory signs of malignant hyperthermia in individuals judged to be malignant hyperthermia susceptible.

Contra-Indications of Dantrolene Sodium

• people with a pre-existing liver disease
• people with compromised lung function
• people with severe cardiovascular impairment
• people with a known hypersensitivity to dantrolene
• pediatric patients under five years of age
• Severe heart disease
• Hepatitis
• Liver problems
• Chronic obstructive lung disease
• Allergy to dantrolene
• People who need good muscular balance or strength to maintain an upright position, motoric function, or proper neuromuscular balance.

The Dosage of Dantrolene Sodium

Strengths: 25 mg; 50 mg; 100 mg; 200 mg; 250 mg

Chronic Spasticity

For use in controlling the manifestations of clinical spasticity resulting from upper motor neuron disorders

• 25 mg orally once daily for 7 days, then
• 25 mg three times a day for 7 days, then
• 50 mg three times a day for 7 days, then
• 100 mg three times a day.

Pediatric Chronic Spasticity

For use in controlling the manifestations of clinical spasticity resulting from upper motor neuron disorders

• 0.5 mg/kg orally once daily for 7 days, then
• 0.5 mg/kg three times a day for 7 days, then
• 1 mg/kg three times a day for 7 days, then
• 2 mg/kg three times a day.

Side Effects of Dantrolene Sodium

The most common

• Abdominal or stomach cramps or discomfort
• abnormal hair growth
• chest pain
• a headache
• joint painPain
• dizziness
• nausea and vomiting
• Severe stomach ache
• epigastric pain,
• diarrhoea,
• anorexia,
• flatulence,
• a headache,
• dizziness,
• fainting, fast or pounding heartbeats.

More common

• Fast or irregular heartbeat
• fever
• Back pain
• dizziness
• a headache
• increased cough
• Acid or sour stomach
• decreased appetite
• Agitation
• chest congestion
• chest pain
• cold sweats
• confusion
• decreased sexual ability or desire
• diarrhea or loose stools
• heartburn
• sleepiness or unusual drowsiness
• stomach or abdominal cramps, gas, or pain
• trouble sleeping

Less common

• Abdominal or stomach cramps or discomfort
• abnormal hair growth
• acne-like rash
• blurred or double vision or any change in vision
• change in taste
• chills and fever
• disturbed color perception
• excessive tearing
• halos around lights
• a headache
• itching skin
• loss of appetite
• night blindness
• the overbright appearance of lights
• redness of skin
• seeing double
• skin rash, encrusted, scaly and oozing
• sleeplessness

Drug Interactions of Dantrolene Sodium

Dantrolene may interact with following drugs, suppliments & may decrease the efficacy of the drug

• antihistamines (e.g,. cetirizine, doxylamine, diphenhydramine, hydroxyzine,loratadine)
• antipsychotic medications (e.g., chlorpromazine, haloperidol, olanzapine, quetiapine, risperidone)

• Calcium channel blockers of the diltiazem/verapamil type: Intravenous treatment with dantrolene and concomitant calcium channel blocker treatment may lead to severe cardiovascular collapse, abnormal heart rhythms, myocardial depressions, and high blood potassium.
• CNS depressants: Sedative action is potentiated. Benzodiazepines may also cause additive muscle weakness.
• Combined oral contraceptives and hormone replacement therapy with estrogens may enhance the liver toxicity of dantrolene, particularly in women over 35 years of age.
• barbiturates (e.g., butalbital, pentobarbital, phenobarbital)
• benzodiazepines (e.g. alprazolam, diazepam, lorazepam)
• beta-blockers (e.g.,carvedilol, metoprolol, propranolol)

Pregnancy & Lactation of Dantrolene Sodium

Pregnancy

This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding

This medication passes into breast milk. This medication should not be used by women who are breast-feeding.

References

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