Approved by the FDA on April 5, 2022, dexmedetomidine sublingual film (Igalmi, manufactured and distributed by BioXcel Therapeutics, Inc., New Haven, CT USA) is indicated in adults for the acute treatment of agitation associated with schizophrenia or bipolar I or II disorder (Table).1,2 It is administered sublingually or buccally under the supervision of a health care provider. After administration, patients should have their vital signs and alertness assessed but there is no FDA Risk Evaluation and Mitigation Strategy (REMS) required for use. A limitation of use is that the safety and effectiveness of dexmedetomidine sublingual film has not been established beyond 24 hours from the first dose.2 There are no contraindications for use.2
Dexmedetomidine is a well-known efficacious alpha-2 adrenergic receptor agonist available since 1999 in an IV formulation indicated for sedation of initially intubated and mechanically ventilated patients in an ICU setting, and sedation of nonintubated patients prior to and/or during surgical and other procedures.3,4 The reformulation of dexmedetomidine as a sublingual film allows the broader use of this agent in psychiatric settings when managing agitation in patients with schizophrenia or bipolar disorder, and thus potentially avoiding the use of IM administration of antipsychotics and/or benzodiazepines. Noninvasive formulations, although requiring cooperation from patients, have the potential to improve overall patient experience, thereby improving future cooperation between patients and health care professionals.5
Dosing
Dexmedetomidine sublingual film is distributed commercially in the following strengths: 180 mcg and 120 mcg. It consists of a lightly mint-flavored, rectangular film containing 2 microdeposits of dexmedetomidine hydrochloride. Dosage strengths of 90 mcg and 60 mcg are available by cutting the 180 mcg or 120 mcg film in half between the 2 visible darker blue dots. The recommended dose depends on the severity of agitation, age, and the presence of hepatic impairment.2 For severe agitation, the recommended dose is 180 mcg. For mild or moderate agitation, the recommended dose is 120 mcg. Dosage is reduced in patients with mild/moderate hepatic impairment (120 mcg for severe agitation and 90 mcg for mild or moderate agitation) or severe hepatic impairment (90 mcg and 60 mcg, for severe and mild/moderate agitation, respectively). The dose recommended for geriatric patients (defined as age ≥65 years) is 120 mcg for either mild, moderate, or severe agitation. Patients are advised not to eat or drink for at least 15 minutes after sublingual administration, or at least 1 hour after buccal administration (defined as placement in the mouth directly behind the lower lip).
If agitation persists after the initial dose, up to 2 additional doses (90 mcg if the initial dose was 180 mcg, otherwise 60 mcg if the initial dose was 120, 90, or 60 mcg) may be given at least 2 hours apart. Assessment of vital signs, including orthostatic measurements, is required prior to the administration of any subsequent doses. Due to risk of hypotension, additional doses are not recommended in patients with systolic blood pressure <90 mm Hg, diastolic blood pressure <60 mm Hg, heart rate <60 beats per minute, or postural decrease in systolic blood pressure ≥20 mm Hg or in diastolic blood pressure ≥10 mm Hg.
Mechanism of action and pharmacodynamics
Dexmedetomidine is an alpha-2 adrenergic receptor agonist and the mechanism of action in the acute treatment of agitation is thought to be due to activation of presynaptic alpha-2 adrenergic receptors.2 Binding affinities (Ki values) are 4 to 6 nM at the alpha-2 adrenergic receptor subtypes.2
Dexmedetomidine exhibits concentration-dependent QT prolongation, with mean QTc increases from baseline from 6 msec (120 mcg single dose) to 11 msec (180 mcg plus 2 additional doses of 90 mcg 2 hours apart for a total of 3 doses).2 Placing the observation about QTc prolongation into clinical context, studies of IM administration of ziprasidone 20 mg and 30 mg and haloperidol 7.5 mg and 10 mg resulted in changes of the QTc interval of 4.6 msec and 6.0 msec, respectively, after 1 dose.6 After a second injection, these values were 12.8 msec and 14.7 msec, respectively.6
Clinical pharmacokinetics
The sublingual film formulation is absorbed orally, bypassing first-pass metabolism, and achieving higher dexmedetomidine bioavailability than ingested formulations.7 Exposure is dose-dependent, with dexmedetomidine being quantifiable in plasma after 5 to 20 minutes post dosing, and with a plasma half-life of 2 to 3 hours.2,8 Mean time for the film to dissolve in the mouth was approximately 6 to 8 minutes following sublingual administration, and 18 minutes following buccal administration.2 Absolute bioavailability was approximately 72% and 82% following sublingual and buccal administration, respectively.2 Mean maximal plasma concentrations of dexmedetomidine were reached approximately 2 hours after sublingual or buccal administration.2 Compared to drinking water at 2 hours post administration, early water intake (as early as 15 minutes post-dose) had minimal effects on the rate or extent of sublingual absorption but was not assessed after buccal administration.2 The average protein binding was 94% and was constant across the different plasma concentrations evaluated and similar in males and females, but significantly decreased in participants with hepatic impairment compared to healthy individuals.2 In contrast, the pharmacokinetic profile of dexmedetomidine is not significantly different in patients with creatinine clearance <30 mL/minute compared to those with normal renal function.2 Dexmedetomidine undergoes almost complete biotransformation to inactive metabolites via direct glucuronidation as well as cytochrome P450 (CYP) (primarily CYP2A6)–mediated metabolism.2 There is no evidence of any CYP–mediated drug interactions that are likely to be of clinical relevance.2
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