Chemical formula: C₁₃H₁₆N₂ Molecular mass: 200.28 g/mol PubChem compound: 5311068
Dexmedetomidine interacts in the following cases:
Care should be taken in severe hepatic impairment as excessive dosing may increase the risk of adverse reactions, over-sedation or prolonged effect as a result of reduced dexmedetomidine clearance.
Inhibition of CYP enzymes including CYP2B6 by dexmedetomidine has been studied in human liver microsome incubations. In vitro study suggests that interaction potential in vivo exists between dexmedetomidine and substrates with dominant CYP2B6 metabolism.
Co-administration of dexmedetomidine with anaesthetics, sedatives, hypnotics, and opioids is likely to lead to an enhancement of effects, including sedative, anaesthetic and cardiorespiratory effects. Specific studies have confirmed enhanced effects with isoflurane, propofol, alfentanil, and midazolam.
No pharmacokinetic interactions between dexmedetomidine and isoflurane, propofol, alfentanil and midazolam have been demonstrated. However, due to possible pharmacodynamic interactions, when co-administered with dexmedetomidine, a reduction in dosage of dexmedetomidine or the concomitant anaesthetic, sedative, hypnotic or opioid may be required.
There are no or limited amount of data from the use of dexmedetomidine in pregnant women.
Studies in animals have shown reproductive toxicity. Dexmedetomidine should not be used during pregnancy unless the clinical condition of the woman requires treatment with dexmedetomidine.
Dexmedetomidine is excreted in human milk, however levels will be below the limit of detection by 24 hours following treatment discontinuation. A risk to infants cannot be excluded. A decision must be made whether to discontinue breastfeeding or to discontinue dexmedetomidine therapy taking into account the benefit of breastfeeding for the child and the benefit of therapy for the woman.
In the rat fertility study, dexmedetomidine had no effect on male or female fertility. No human data on fertility are available.
Patients should be advised to refrain from driving or other hazardous tasks for a suitable period of time after receiving dexmedetomidine for procedural sedation.
The most frequently reported adverse reactions with dexmedetomidine in ICU setting are hypotension, hypertension and bradycardia, occurring in approximately 25%, 15% and 13% of patients respectively. Hypotension and bradycardia were also the most frequent dexmedetomidine-related serious adverse reactions occurring in 1.7% and 0.9% of randomised Intensive Care Unit (ICU) patients respectively.
The most frequently reported adverse reactions with dexmedetomidine in procedural sedation are listed below (the protocols of phase III studies contained pre-defined thresholds for reporting changes in blood pressure, respiratory rate and heart rate as AEs).
The adverse reactions listed below have been accumulated from pooled data of clinical trials in intensive care.
Adverse reactions are ranked under headings of frequency, the most frequent first, using the following convention: Very common (≥1/10); common (≥1/100 to <1/10); uncommon (≥1/1,000 to <1/100); rare (≥1/10,000 to <1/1,000), very rare (<1/10,000).
Adverse reactions:
Common: Hyperglycaemia, hypoglycaemia
Uncommon: Metabolic acidosis, hypoalbuminaemia
Common: Agitation
Uncommon: Hallucination
Very common: Bradycardia1,2
Common: Myocardial ischaemia or infarction, tachycardia
Uncommon: Atrioventricular block first degree, cardiac output decreased
Very common: Hypotension1,2, hypertension1,2
Very common: Respiratory depression2,3
Uncommon: Dyspnoea, apnoea
Common: Nausea2, vomiting, dry mouth2
Uncommon: Abdominal distension
Not known: Polyuria
Common: Withdrawal syndrome, hyperthermia
Uncommon: Drug ineffective, thirst
1 See section on Description of selected adverse reactions
2 Adverse reaction observed also in procedural sedation studies
3 Incidence ‘common’ in ICU sedation studies
In relatively healthy non-ICU subjects treated with dexmedetomidine, bradycardia has occasionally led to sinus arrest or pause. The symptoms responded to leg raising and anticholinergics such as atropine or glycopyrrolate. In isolated cases bradycardia has progressed to periods of asystole in patients with pre-existing bradycardia.
Hypertension has been associated with the use of a loading dose and this reaction can be reduced by avoiding such a loading dose or reducing the infusion rate or size of the loading dose.
Children >1 month post-natal, predominantly post-operative, have been evaluated for treatment up to 24 hours in the ICU and demonstrated a similar safety profile as in adults. Data in new-born infants (28–44 weeks gestation) is very limited and restricted to maintenance doses ≤0.2 mcg/kg/h. A single case of hypothermic bradycardia in a neonate has been reported in the literature.
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