Dexmedetomidine
Mechanism :
It is a new generation highly selective alpha 2 adrenergic receptor agonist that has sedative and pain relieving effects. Sympatholytic properties without significant ventilatory effects.
Indication :
- For ICU sedation
- For procedural sedation
Contraindications :
Hypersensitivity to the drug or it’s components
Avoid abrupt withdrawal or its prolonged use
Caution in geriatric population, low blood pressure, low heart rate, 2nd/3rd degree AV block, severe ventricular dysfunction, hypovolemia, liver dysfunction, sick sinus syndrome, diabetes mellitus.
Dosing :
Available as an injection.
For ICU sedation:
0.2-1 mcg/kg/hour via intravenous route
Initiate a dose of 0.25-2 mcg/kg/dose intravenously x1. Maximum dose: 2 mcg/kg/hour, titrate the dose to effect
In kids <1 year, a higher infusion rate may be necessary, taper the dose gradually to D/C if there is prolonged use
For procedural sedation:
Via intravenous route: 0.3-2 mcg/kg/hour intravenous, Start: 0.5-3 mcg/kg/dose IV x1
Via intramuscular route: 1- 4.5 mcg/kg/dose IM x1, can repeat with a lower dose x1 after 10 minutes
Via intranasal route:1-2 mcg/kg/dose intranasally x1, can use injectable form with a mucosal atomization device, divide dose and give as 1 spray in each nostril x1
Adverse Effect :
>10%: Nausea, low blood pressure, high blood pressure
1-10%: Fever, chills, rigors, reduced pulse rate, atrial fibrillation, dry mouth, emesis, increased pulse rate, elevated blood sugars, anaemia, agitation, hypoxia, hypovolemia, atelectasis, post-procedural bleeding, hyperthermia, reduced urine output, pain, polydipsia, acidosis, pleural effusion, reduced calcium levels, pulmonary edema, elevated heart rate.
<1%: Ventricular tachycardia, wheeze, swelling of lower limbs.
According to post- marketing reports:
Hematologic disorders: Anaemia
Cardiovascular disorders: Rhythm derangements, atrial fibrillation, AV block, low heart rate, elevated heart rate, extrasystoles, SVT, ventricular arrhythmia, cardiac arrest, ventricular tachycardia and myocardial infarction.
Ophthalmic disorders: Photopsia, vision loss
GIT disorders: Abdominal ache, loose stools, nausea, emesis
Others: Chills, hyperthermia, pain, fever, polydipsia
Deranged laboratory values: Elevated liver function panel, elevated urea, GGT, prolonged QT interval or EKG T wave inversion.
Metabolic disorders: Acidosis, elevated sodium level, elevated potassium level, low blood glucose, low blood volume.
CNS disorders: Seizures, dizziness, headache, nerve pain, neuritis, derange speech or speech disorder.
Psychiatric disorders: Agitation, confusion, delirium, hallucinations, illusions
Urinary disorders: Oliguria, polyuria
RS disorders: Bronchospasm, breathlessnes, hypoventilation, hypoxia, pulmonary congestion, apnea, respiratory acidosis and hypercapnia.
Skin, subcutaneous tissue disorders: Hyperhidrosis, itching, rash, urticaria
Surgical, medical procedures: Light anaesthesia
Vascular disorders: Blood pressure derangements such as elevated BP or low BP, bleeding
Interaction :
Aceclofenac, abacavir, albendazole, alprazolam, allopurinol, amiodarone, benzocaine, bisoprolol, bosentan, bupropion, canagliflozin, carboplatin, cefazolin, cefotaxime, cetirizine are some drugs that can interact with this drug.
Lactation :
There is no available human data to measure risk of hazard to the infant or its effects on milk production or its excretion in milk. In animal reproduction studies, it was observed that radio-labeled dexmedetomidine when injected subcutaneously to lactating female rats was excreted in their milk. Hence, maintain caution when giving it to lactating women and consider weighing pros and cons of the drug and the benefits of breastfeeding.
Hepatic Dose :
Consider administering a lower dose in hepatic disease
Pregnanacy :
There is limited human data to measure risk of hazards to the growing fetus when the drug is used in pregnancy. Caution must be exercised as there is a higher risk of neonatal hypotension and low heart rate, however, there is low risk of teratogenicity.
In an in-vitro human placental study, there was placental transfer of dexmedetomidine. Hence, use in pregnancy only if potential benefits justify potential fetal risk.
In animal reproduction studies, there was found to be a higher risk of low fetal weight and embryo-fetal morbidity and a potential risk of increased uterine contractions based on dexmedetomidine’s mechanism of action.