A pharmacokinetic and pharmacodynamic study, in healthy volunteers, of a rapidly absorbed intranasal midazolam formulation

Effect of intranasal and oral administration of levetiracetam on the temporal and spatial distributions of SV2A in the KA-induced rat model of SE

To investigate the effectiveness of nasal delivery of levetiracetam (LEV) on the distributions of synaptic vesicle protein 2 isoform A (SV2A) in epileptic rats with injection of kainic acid (KA) into amygdala. A total of 138 rats were randomly divided into four groups, including the Sham surgery group, the epilepsy group (EP), and the LEV oral administration (LPO) and nasal delivery (LND) groups. The rat intra-amygdala KA model of epilepsy was constructed. Pathological changes of rat brain tissue after status epilepticus (SE) were detected using haematoxylin and eosin staining. Expression of SV2A in rat hippocampus after SE was evaluated using the western blotting analysis. Expression and distribution of SV2A in rat hippocampus after SE were detected based on immunofluorescence staining. The EP group showed evident cell loss and tissue necrosis in the CA3 area of hippocampus, whereas the tissue damage in both LPO and LND groups was significantly reduced. Western blotting analysis showed that the expressions of SV2A in the hippocampus of both EP and LND groups were significantly decreased 1 week after SE, increased to the similar levels of the Sham group in 2 weeks, and continuously increased 4 weeks after SE to the level significantly higher than that of the Sham group. Results of immunofluorescence revealed largely the same expression patterns of SV2A in the CA3 area of hippocampus as those in the entire hippocampus. Our study revealed the same antiepileptic and neuronal protective effects by the nasal and oral administrations of LEV, without changing the expression level of SV2A.

Safety, Pharmacokinetics, and Pharmacodynamics of Midazolam Gel After Rectal Administration in Healthy Chinese Subjects

BACKGROUND AND OBJECTIVES

Midazolam rectal gel is a novel rectal formulation that may be a promising and potential alternative to oral administration for pediatric sedation. The objective of this study was to evaluate the safety, pharmacokinetics, pharmacodynamics, and absolute bioavailability of midazolam rectal gel in healthy Chinese subjects.

METHODS

An open-label, single-dose, randomized, two-period, two-treatment, crossover clinical study was conducted in 22 healthy subjects (16 males and six females), each receiving 2.5 mg intravenous midazolam in one period and 5 mg midazolam rectal gel in another period (the dosages here were calculated as active midazolam). Safety, pharmacokinetic, and pharmacodynamic assessments were conducted throughout the study.

RESULTS

All of the subjects completed both treatment periods. The formulation of rectal gel was well tolerated, with no serious adverse events occurring. After a single rectal dose of 5 mg midazolam rectal gel, it was absorbed rapidly with a median value of time to peak concentration (T_max) of 1.00 h, and mean values of the peak concentration (C_max) and area under the concentration-time curve (AUC_0-t) of 37.2 ng/mL and 137 h·ng/mL, respectively. The absolute bioavailability of rectal gel was 59.7%. The rectal gel exhibited a relatively delayed onset but a more stable sedative effect and a longer duration when compared with intravenous midazolam.

CONCLUSION

Midazolam rectal gel may be a feasible alternative with a high level of acceptance in pediatric sedation and enhanced bioavailability compared to an oral formulation. The modeling results may help to disclose out the exposure-response relationship of midazolam rectal gel and support the design of an escalating-doses study and pediatric extrapolation study.

CLINICAL TRIAL REGISTRATION

The study was registered at http://www.chinadrugtrials.org.cn (No. CTR20192350).

What's New in Intravenous Anaesthesia? New Hypnotics, New Models and New Applications

New anaesthetic drugs and new methods to administer anaesthetic drugs are continually becoming available, and the development of new PK-PD models furthers the possibilities of using arget controlled infusion (TCI) for anaesthesia. Additionally, new applications of existing anaesthetic drugs are being investigated. This review describes the current situation of anaesthetic drug development and methods of administration, and what can be expected in the near future.

Benzodiazepines in the Management of Seizures and Status Epilepticus: A Review of Routes of Delivery, Pharmacokinetics, Efficacy, and Tolerability

Status epilepticus (SE) is an acute, life-threatening medical condition that requires immediate, effective therapy. Therefore, the acute care of prolonged seizures and SE is a constant challenge for healthcare professionals, in both the pre-hospital and the in-hospital settings. Benzodiazepines (BZDs) are the first-line treatment for SE worldwide due to their efficacy, tolerability, and rapid onset of action. Although all BZDs act as allosteric modulators at the inhibitory gamma-aminobutyric acid (GABA)_A receptor, the individual agents have different efficacy profiles and pharmacokinetic and pharmacodynamic properties, some of which differ significantly. The conventional BZDs clonazepam, diazepam, lorazepam and midazolam differ mainly in their durations of action and available routes of administration. In addition to the common intravenous, intramuscular and rectal administrations that have long been established in the acute treatment of SE, other administration routes for BZDs-such as intranasal administration-have been developed in recent years, with some preparations already commercially available. Most recently, the intrapulmonary administration of BZDs via an inhaler has been investigated. This narrative review provides an overview of the current knowledge on the efficacy and tolerability of different BZDs, with a focus on different routes of administration and therapeutic specificities for different patient groups, and offers an outlook on potential future drug developments for the treatment of prolonged seizures and SE.

Physiologically based pharmacokinetic/pharmacodynamic modeling to evaluate the absorption of midazolam rectal gel

OBJECTIVE

We aimed to 1) develop physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) models of a novel midazolam rectal gel in healthy adults, 2) assess the contribution of different physiologically relevant factors in rectal absorption, and 3) to provide supports for future clinical studies of midazolam rectal gel.

METHODS

We developed the rectal PBPK model after built the intravenous and the oral PBPK model. Then, the physiological progress of rectal route was described in terms of the drug release, the rectal absorption and the particle first-pass elimination. Next, the validated PBPK model was combined with the sigmoid E_max PD model. This PBPK/PD model was used to identify the dose range and the critical parameters to ensure safety sedation.

RESULTS

Based on the simulations, the recommended maximum dose for adults' sedation was 15 mg. And the retention time of midazolam rectal gel should be longer than 3 h to reach over 80% pharmacokinetics and pharmacodynamics effects.

CONCLUSION

We successfully developed a PBPK/PD model for the midazolam rectal gel, which accurately described the PK/PD behavior in healthy adults and indicated the transit time of rectum was the most sensitive parameter for absorption. This PBPK/PD model would be expected to support the future clinical studies and pediatric application.

Intranasal Allopregnanolone Confers Rapid Seizure Protection: Evidence for Direct Nose-to-Brain Delivery

Allopregnanolone, a positive modulator of GABAA receptors with antiseizure activity, has potential in the treatment of seizure emergencies. Instillation of allopregnanolone in 40% sulfobutylether-β-cyclodextrin into the nose in mice rapidly elevated the seizure threshold in the timed intravenous pentylenetetrazol (ED50, 5.6 mg/kg), picrotoxin (ED50, 5.9 mg/kg), and bicuculline seizure tests. The effect peaked at 15 min, decayed over 1 h, and was still evident in some experiments at 6 h. Intranasal allopregnanolone also delayed the onset of seizures in the maximal PTZ test. At an allopregnanolone dose (16 mg/kg) that conferred comparable effects on seizure threshold as the benzodiazepines midazolam and diazepam (both at doses of 1 mg/kg), allopregnanolone caused minimal sedation or motor toxicity in the horizontal screen test whereas both benzodiazepines produced marked behavioral impairment. In addition, intranasal allopregnanolone failed to cause loss-of-righting reflex in most animals, but when the same dose was administered intramuscularly, all animals became impaired. Intranasal allopregnanolone (10 mg/kg) caused a rapid increase in brain allopregnanolone with a Tmax of ~5 min after initiation of the intranasal delivery. High levels of allopregnanolone were recovered in the olfactory bulb (Cmax, 16,000 ng/mg) whereas much lower levels (Cmax, 670 ng/mg) were present in the remainder of the brain. We conclude that the unique ability of intranasal allopregnanolone to protect against seizures without inducing behavioral adverse effects is due in part to direct nose-to-brain delivery, with preferential transport to brain regions relevant to seizures. Benzodiazepines are commonly administered intranasally for acute seizure therapy, including for the treatment of acute repetitive seizures, but are not transported from nose-to-brain. Intranasal allopregnanolone acts with greater speed, has less propensity for adverse effects, and has the ability to overcome benzodiazepine refractoriness. This is the first study demonstrating rapid functional central nervous system activity of a nose-to-brain-delivered steroid. Intranasal delivery circumvents the poor oral bioavailability of allopregnanolone providing a route of administration permitting its evaluation as a treatment for diverse neuropsychiatric indications.

Principles of Pharmacotherapy of Seizures and Status Epilepticus

Status epilepticus is a neurological emergency with an outcome that is highly associated with the initial pharmacotherapy management that must be administered in a timely fashion. Beyond first-line therapy of status epilepticus, treatment is not guided by robust evidence. Optimal pharmacotherapy selection for individual patients is essential in the management of seizures and status epilepticus with careful evaluation of pharmacokinetic and pharmacodynamic factors. With the addition of newer antiseizure agents to the market, understanding their role in the management of status epilepticus is critical. Etiology-guided therapy should be considered in certain patients with drug-induced seizures, alcohol withdrawal, or autoimmune encephalitis. Some patient populations warrant special consideration, such as pediatric, pregnant, elderly, and the critically ill. Seizure prophylaxis is indicated in select patients with acute neurological injury and should be limited to the acute postinjury period.

Pharmacokinetics and pharmacodynamics of intranasal remimazolam-a randomized controlled clinical trial

PURPOSE

Remimazolam is a novel and ultra-short-acting sedative currently developed for intravenous use in procedural sedation, general anesthesia, and ICU sedation. However, intravenous administration is not always appropriate, depending on the patient or setting. This study evaluated intranasal administration as a potential alternative route.

METHODS

The study used a randomized, double-blind, 9 period cross-over design to compare the pharmacokinetics, pharmacodynamics, and safety of single intranasal doses of 10, 20, and 40 mg remimazolam (as powder or solution) with intranasal placebo and 4 mg intravenous remimazolam.

RESULTS

Intranasal remimazolam powder had a consistent absolute bioavailability of approximately 50%; T_max was 10 min; AUC and C_max were dose-proportional. The higher doses of intranasal solution, however, resulted in decreasing bioavailability and loss of dose-proportionality in AUC and C_max despite complete drug absorption due to partial swallowing of dose and the resulting first-pass effect. Pharmacodynamics were generally consistent with PK. Peak effects (drowsiness, relaxation, any, memory, response time) were in similar ranges after intranasal (10 to 40 mg) as intravenous (4 mg) dosing and were partially, but not consistently, dose-related. Safety results were generally consistent with other benzodiazepines; however, intranasal remimazolam (but not placebo) caused nasal discomfort/pain, in some cases even severe.

CONCLUSIONS

Intranasal administration of remimazolam was safe and caused sedative effects. However, the severe pain and discomfort caused by intranasal remimazolam prohibit its use by this route of administration, at least with the currently available intravenous formulation.

In vitro-in vivo extrapolation of metabolic clearance using human liver microsomes: factors showing variability and their normalization

In vitro-in vivo extrapolation (IVIVE) using human liver microsomes has been widely used to predict metabolic clearance, but some of the factors used in the process of prediction show variability for the same compound: notably, microsomal intrinsic clearance values corrected by the unbound fraction (CL_{int, u}), physiological parameters used for scale-up, and the source of in vivo clearance data.The purpose of this study was to assess the correlation between in vitro and in vivo CL_int with a focus on factors showing variability using four cytochrome P450 (CYP)3A substrates.We surveyed in vivo clearance values in literature and also determined the microsomal CL_{int, u} values. A scaling factor (SF_direct) was defined as in vivo CL_int divided by the microsomal CL_{int, u}, which ranged from 1190 to 2310 (mg protein per kg body weight). The application of a mean SF_direct of 1600 (mg protein per kg body weight) and further normalization by the microsomal CL_{int, u} values of midazolam, the most commonly used substrate, resulted in improved prediction accuracy for CL_{int, u} values from various microsomal batches.The results suggest the normalization of variability might be useful for predicting the in vivo CL_int.

omparative Evaluation of the Intranasal Spray Formulation of Midazolam and Dexmedetomidine in Patients Undergoing Surgical Removal of Impacted Mandibular Third Molars: A Split Mouth Prospective Study

Purpose

The purpose of this prospective randomized single blinded split mouth study was to conduct a comparative evaluation of the efficacy of intranasal atomised spray formulation of Dexmedetomidine with Midazolam in patients undergoing surgical removal of bilaterally impacted mandibular third molars.

Methods

This prospective study was conducted in twenty volunteers. Each volunteer underwent the surgical removal of an impacted mandibular third molar at two separate appointments at an interval of two weeks. The first third molar surgery was conducted using either intranasal Midazolam (Group M) or intranasal Dexmedetomidine (Group D). At the second appointment the surgical procedure was performed using the sedative agent not used at the first appointment. The primary testing outcome variables were Plasma oxygen saturation (SpO2), pulse and blood pressure and Modified Observer's Assessment of Alertness/Sedation (OAA/S) scale. These were recorded at predetermined intervals starting 10 min before the administration of local anaesthesia and continued up to 10 min after completion of the procedure. In addition surgeon's opinion regarding the patient cooperation, event amnesia, post operative nausea & vomiting were obtained.

Results

The sample composed of twenty patients (M = 9 and F = 11). There was statistically no significant difference between Group M and Group D with respect to mean SpO2. Minor differences were however noted at 20 and 30 min after sedation. There was no significant difference between the groups with respect to mean pulse rate, blood pressure, OAA/S, event amnesia, post operative nausea and vomiting and patient cooperation.

Conclusion

We conclude that Midazolam and Dexmedetomidine are equivalent and can be used in minor oral surgery with minimal complications. These drugs can be used intranasally using nasal atomization device in routine outpatient basis in otherwise normal healthy but anxious patients. All procedures must however be performed in the presence of an anaesthesiologist and with ready availability of emergency drugs and equipment.

Evaluating Clinical Effectiveness and Pharmacokinetic Profile of Atomized Intranasal Midazolam in Children Undergoing Laceration Repair

BACKGROUND

Atomized intranasal midazolam is a common adjunct in pediatrics for procedural anxiolysis. There are no previous studies of validated anxiety scores with pharmacokinetic data to support optimal procedure timing.

OBJECTIVES

We describe the clinical and pharmacokinetic profile of atomized intranasal midazolam in children presenting for laceration repair.

METHODS

Children 11 months to 7 years of age and weighing <26 kg received 0.4 mg/kg of atomized intranasal midazolam for simple laceration repair. Blood samples were obtained at 3 time points in each patient, and the data were fit with a 1-compartment model. Patient anxiety was rated with the Observational Scale of Behavioral Distress. Secondary outcomes included use of adjunctive medications, successful completion of procedure, and adverse events.

RESULTS

Sixty-two subjects were enrolled, with a mean age of 3.3 years. The median time to peak midazolam concentration was 10.1 min (interquartile range 9.7-10.8 min), and the median time to the procedure was 26 min (interquartile range 21-34 min). There was a trend in higher Observational Scale of Behavioral Distress scores during the procedure. We observed a total of 2 adverse events, 1 episode of vomiting (1.6%) and 1 paradoxical reaction (1.6%). Procedural completion was successful in 97% of patients.

CONCLUSIONS

Atomized intranasal midazolam is a safe and effective anxiolytic to facilitate laceration repair. The plasma concentration was >90% of the maximum from 5 to 17 min, suggesting this as an ideal procedural timeframe after intranasal midazolam administration.

Development and validation of a sensitive assay for analysis of midazolam, free and conjugated 1-hydroxymidazolam and 4-hydroxymidazolam in pediatric plasma: Application to Pediatric Pharmacokinetic Study

Pharmacokinetic, pharmacodynamic and pharmacogenomic studies of midazolam are currently being performed in critically ill children to find suitable dose regimens. Sensitive assays using small volumes of plasma are necessary to determine the concentrations of midazolam and its respective metabolites in pediatric studies. Midazolam is metabolized to hydroxylated midazolam isomers, which are present as free as well as the corresponding glucuronide conjugates. A high-performance liquid chromatographic method with tandem mass spectrometry has been developed and validated for the quantification of midazolam, and free and total 1-hydroxymidazolam and 4-hydroxymidazolam metabolites in small volumes of plasma. Cleanup consisted of 96-well μ-elution solid phase extraction (SPE). The analytes were separated by gradient elution using a C₁₈ analytical column with a total run time of 5min. Multiple reaction monitoring was employed using precursor to product ion transitions of m/z 326.2→291.3 for midazolam, m/z 342.1→203.0 for 1-hydroxymidazolam, m/z 342.1→325.1 for 4-hydroxymidazolam and m/z 330.2→295.3 for ²H₄-midazolam (internal standard). Since authentic hydroxymidazolamglucuronide standards are not available, samples were hydrolyzed with β-glucuronidase under optimized conditions. Assay conditions were modified and optimized to provide appropriate recovery and stability because 4-hydroxymidazolam was very acid sensitive. Standard curves were linear from 0.5 to 1000ng/mL for all three analytes. Intra- and inter day accuracy and precision for quality control samples (2, 20, 200 and 800ng/mL) were within 85-115% and 15% (coefficient of variation), respectively. Stability in plasma and extracts were sufficient under assay conditions. Plasma samples were processed and analyzed for midazolam, and free 1-hydroxymidazolam and 4-hydroxymidazolam metabolites. Plasma samples that were hydrolyzed with β-glucuronidase were processed and analyzed for midazolam, and total 1-hydroxymidazolam and 4-hydroxymidazolam metabolites under the same assay conditions. The difference in concentration between the total and free hydroxymidazolam metabolites provided an estimate of conjugated hydroxymidazolam metabolites. The combination of 96-well μ-elution SPE and LC-MS/MS allows reliable quantification of midazolam and its metabolites in small volumes of plasma for pediatric patients. This assay is currently being successfully utilized for analysis of samples from ongoing clinical trials.

A randomised, double-blind controlled trial of intranasal midazolam for the palliation of dyspnoea in patients with life-limiting disease

PURPOSE

Anxiety is a major component of breathlessness and is often palliated with benzodiazepines. Midazolam is a short-acting water-soluble benzodiazepine with a rapid onset of action and short half-life. Intranasal midazolam had been shown to be of marked clinical benefit in an uncontrolled pilot study for the control of dyspnoea. A blinded randomised controlled study was therefore undertaken across four Australasian palliative care services.

METHODS

All participants received six numbered study nasal spray (SNS) bottles, three of which contained midazolam and three placebo. They were instructed to use one SNS bottle on each day they were breathless, for 6 days within 2 weeks. Dyspnoea scores were recorded before and at set time intervals following the first use of each SNS bottle.

RESULTS

Across all SNS bottles, the maximum change of 2.1 on an 11-point numerical rating scale was seen at 60 min. There was no difference in dyspnoea score between the two arms. Approximately 50 % of participants in each arm had a positive response (i.e. ≥2 point change in dyspnoea score from baseline). Anxiety scores at baseline were low. The most common adverse event was local nasal reactions.

CONCLUSION

Intranasal midazolam had no clinical benefit over intranasal placebo for the control of dyspnoea. The low level of anxiety at baseline and dose of active drug delivered may have been important factors. Many participants found the SNS bottles to be a challenging mode of drug delivery. This study confirms the importance of placebo-controlled trials for defining best clinical practise.

Pharmacokinetics, pharmacodynamics, and safety of USL261, a midazolam formulation optimized for intranasal delivery, in a randomized study with healthy volunteers

OBJECTIVE

To compare the pharmacokinetics, pharmacodynamics, and tolerability of USL261, a midazolam formulation optimized for intranasal delivery, versus midazolam intravenous (IV) solution administered intranasally (MDZ-inj IN) or intravenously (MDZ-inj IV) in healthy adults.

METHODS

In this phase 1, five-way crossover, open-label study, 25 healthy adults (aged 18-42 years) were randomly assigned to receive 2.5, 5.0, and 7.5 mg USL261; 2.5 mg MDZ-inj IV; and 5.0 mg MDZ-inj IN. Blood samples were collected for 12 h post dose to determine pharmacokinetic profiles. Pharmacodynamic assessments of sedation and psychomotor impairment also were conducted. Adverse events, oxygen saturation, and vital signs were recorded.

RESULTS

Increasing USL261 dose corresponded with increases in midazolam area under the concentration time curve (AUC) and maximum observed plasma concentration (Cmax ), with all doses demonstrating rapid median time to Cmax (Tmax ; 10-12 min). USL261 also demonstrated increased absorption, with a 134% relative bioavailability, compared with the same MDZ-inj IN dose. USL261 was associated with dose-dependent increases in sedation and psychomotor impairment (p < 0.05); however, these effects lasted <4 h and generally did not differ from MDZ-inj IN or MDZ-inj IV at comparable doses. No serious adverse events (SAEs) or deaths were reported, and no treatment-emergent adverse events (TEAEs) led to study discontinuation.

SIGNIFICANCE

Compared with intranasal delivery of a midazolam formulation intended for IV delivery, USL261, optimized for intranasal administration demonstrated improved bioavailability with similar pharmacodynamic effects. Therefore, USL261 may be a preferable alternative to the currently approved rectal diazepam treatment for intermittent bouts of increased seizure activity.

Seizures induced by recreational abuse of bupropion tablets via nasal insufflation

Bupropion is a newer generation antidepressant that is commonly used for treatment of depression and for smoking cessation. Seizures are a frequently reported adverse effect of bupropion in therapeutic oral doses; however, there are limited data about the consequences of nasal insufflation of bupropion. We report the case of a patient who presented to the emergency department (ED) with a recent history of generalized tonic–clonic seizures whose etiology was initially a diagnostic mystery. After an initial visit to another ED, the patient presented to our ED later that day with a recurrence of the seizures after crushing and nasally insufflating oral bupropion tablets. We review important implications of this case to emergency medicine, including the potential for abuse of bupropion, the difference between intranasal and oral administration, the changing trends in the etiology of drug-related seizures and the importance of examining the nares in patients with unexplained seizure and delirium.

Comparative pharmacokinetics and bioavailability of intranasal and rectal midazolam formulations relative to buccal administration in rabbits

The rectal and intranasal formulations under current development demonstrated comparative potential for administering midazolam in treating seizures in a medical emergency service.

Outpatient pharmacotherapy and modes of administration for acute repetitive and prolonged seizures

Acute repetitive seizures (ARS) are a serious epilepsy phenomenon, generally described as closely grouped seizures over minutes to 2 days, representing an increase in seizure frequency compared with baseline. In some instances, ARS may not stop without treatment, and evolution into status epilepticus is a significant concern. Additionally, neuronal injury may occur after even brief repeated seizures. Given the substantial risks that may be involved with ARS, it is crucial to develop appropriate protocols for identification and management of this seizure phenomenon. This article focuses on pharmacotherapy and, in particular, different modes of administering medication for ARS in the outpatient setting. Our aim was to present a review of data from non-randomized and randomized, controlled trials to evaluate the efficacy, safety and tolerability of out-of-hospital ARS treatments. Several of the studies included patients with ARS, as well as patients with prolonged seizures. Prolonged seizures, or seizures lasting greater than 5 min, have similar risks and treatment options to those of ARS; therefore, this discussion also includes treatment trials and recommendations for prolonged seizures. All trials used benzodiazepines, a class of drugs that are ideal for the ARS and prolonged seizure populations because of their rapid onset of action and minimal adverse effects. Rectal diazepam is currently the only formulation approved by the US Food and Drug Administration (FDA) for out-of-hospital treatment. Oral benzodiazepines are appropriate only for mild ARS. Intramuscular diazepam autoinjection has shown success against ARS in clinical trials. Intranasal midazolam and diazepam are in testing. Other treatments have also been explored--specifically, buccal midazolam (approved in the European Union), sublingual lorazepam and intranasal lorazepam.

Development of benzodiazepines for out-of-hospital management of seizure emergencies

Management of seizure emergencies substantially changed after the introduction of rectal diazepam in Europe in the 1970s and in the United States in the 1990s. Although safe and effective, social objections and legal concerns have limited use of rectal diazepam products in out-of-hospital treatment of seizure emergencies. Shortly after the introduction of Diastat (diazepam rectal gel), commercial development of innovative formulations began involving several benzodiazepines and routes of administration, including buccal, IM, nasal, and subcutaneous. All benzodiazepines have the same mechanism of action; however, there are major differences in physicochemical properties and pharmacokinetic characteristics, which affect the choice of drug and route. This article highlights some of those differences and their effect on selection of therapies for treating seizure emergencies. We also present results from key clinical studies of these drugs and provide an update on current status of new products under development.

Seizure protection by intrapulmonary delivery of midazolam in mice

The lung provides a portal of entry that could be used to rapidly deliver anticonvulsant substances to the brain to treat seizures. In the present study, we demonstrate that midazolam, a water-soluble anticonvulsant benzodiazepine, confers potent seizure protection when administered via the intrapulmonary route. High dose (100 mg/kg) intraperitoneal midazolam induced loss-of-righting reflex in mice. Lower doses of midazolam (100-1000 μg/kg) when administered intraperitoneally did not induce loss-of-righting reflex but protected animals against pentylenetetrazol (PTZ)-induced seizures. Intrapulmonary administration of midazolam via a tracheal cannula protected against intraperitoneal PTZ seizures at lower doses. The minimal intraperitoneal and intravenous doses of midazolam required to elevate the threshold for seizure signs induced by intravenous PTZ were 500 and 100 μg/kg, respectively, whereas the minimal intrapulmonary midazolam dose was 12.5 μg/kg. Intratracheal midazolam caused a large increase in intravenous PTZ threshold 5 min after administration but the effect declined rapidly over 60 min and no antiseizure activity was evident at 120 min. The minimal intraperitoneal doses of midazolam required to elevate the threshold for seizure signs induced by intravenous picrotoxin and kainic acid were 100 and 2000 μg/kg, respectively; the corresponding values for intratracheal midazolam were 25 and 100 μg/kg, respectively. We conclude that midazolam is a highly effective anticonvulsant when administered by the intrapulmonary route. Midazolam is substantially more potent when delivered into the lung than when administered intraperitoneally or intravenously. Inhalation could be an alternative to other routes of administration for the delivery of midazolam to rapidly abort acute seizures.

Bioavailability of a novel midazolam gel after intranasal administration in dogs

OBJECTIVE

To compare the pharmacokinetics of a novel bioadhesive gel formulation of midazolam after intranasal (IN) administration with that of midazolam solution after IN, IV, and rectal administration to dogs.

ANIMALS

10 (5 males and 5 females) healthy adult Beagles.

PROCEDURES

Dogs were assigned to 4 treatment groups for a crossover study design. Initially, midazolam solution (5 mg/mL) was administered (0.2 mg/kg) IV to group 1, rectally to group 2, and IN to group 3; a 0.4% hydroxypropyl methylcellulose midazolam gel formulation (50 mg/mL) was administered (0.2 mg/kg, IN) to group 4. Each dog received all 4 treatments; there was a 7-day washout period between subsequent treatments. Blood samples were collected before and after midazolam administration. Plasma concentration of midazolam was determined by use of high-performance liquid chromatography.

RESULTS

The peak plasma concentration after IN administration of the gel formulation was significantly higher than that after IN and rectal administration of the solution. Mean ± SD time to peak concentration was 11.70 ± 2.63 minutes (gel IN), 17.50 ± 2.64 minutes (solution IN), and 39 ± 14.49 minutes (solution rectally). Mean bioavailability of midazolam was 70.4% (gel IN), 52.0% (solution IN), and 49.0% (solution rectally). Bioavailability after IN administration of the gel formulation was significantly higher than that after IN and rectal administration of the solution.

CONCLUSIONS AND CLINICAL RELEVANCE

IN administration of midazolam gel was superior to both IN and rectal administration of midazolam solution with respect to peak plasma concentration and bioavailability.

Current oral and non-oral routes of antiepileptic drug delivery

Antiepileptic drugs are commonly given orally for chronic treatment of epilepsy. The treatment of epilepsy requires administration of medications for both acute and chronic treatment using multiple types of formulations. Parenteral routes are used when the oral route is unavailable or a rapid clinical response is required. Lorazepam and midazolam can be administered by the buccal, sublingual or intranasal routes. Consensus documents recommend rectal diazepam, buccal midazolam or intranasal midazolam for the out-of-hospital treatment of early status epilepticus. In the United States, diazepam is the only FDA approved rectal formulation. With the lack of parenteral, buccal or intranasal formulations for many of the antiepileptic drugs, the use of the rectal route of delivery to treat acute seizures or to maintain therapeutic concentrations is suitable for many, but not all antiepileptic medications. There is a significant need for new non-oral formulations of the antiepileptic drugs when oral administration is not possible.

The effect of hydroxypropyl-beta-cyclodextrin and sucrose on the sublingual absorption of midazolam in rabbits

Sublingually administered midazolam is commonly used for premedication of pediatric patients. However, the irritating taste and low aqueous solubility of midazolam complicate its sublingual use. Cyclodextrin complexation can be used to improve both the taste and aqueous solubility of drugs, but based on earlier studies, the complexation efficiency of midazolam is relatively low. In the present study, the complexation of midazolam with hydroxypropyl-beta-cyclodextrin (HP-β-CD) was investigated in the presence of various excipients. The aqueous solubility of midazolam improved significantly when HP-β-CD was used together with sucrose. Sucrose alone did not increase the solubility of midazolam. In addition, sucrose increased the apparent stability constant of the midazolam/HP-β-CD complex. The pharmacokinetics of midazolam in different dosage forms was investigated in rabbits (dose 1mg/rabbit) after intravenous administration of midazolam solution and after sublingual administration of midazolam solution, midazolam/HP-β-CD/sucrose solution or midazolam/HP-β-CD/sucrose powder. Midazolam displayed rapid sublingual absorption (mean t(max) ≤30min from the liquid formulations and 60 min from the solid formulation) with high absolute bioavailability (>68%) from all evaluated formulations. Based on the results, HP-β-CD and sucrose can be utilized together to prepare more concentrated and palatable midazolam formulations for sublingual administration in pediatric patients.

Pharmacokinetics and tolerability of nasal versus intravenous midazolam in healthy Dutch volunteers: a single-dose, randomized-sequence, open-label, 2-period crossover pilot study

BACKGROUND

Intranasal (IN) midazolam is a potential alternative to rectal diazepam for the acute treatment of epileptic seizures.

OBJECTIVE

The purpose of this pilot study was to investigate the pharmacokinetics and tolerability of IN midazolam (50 mg/mL) compared with intravenous (IV) midazolam (2.5 mg) in healthy adult volunteers.

METHODS

In this single-dose, randomized-sequence, open-label, 2-period crossover pilot study subjects were randomly assigned to receive IN or IV midazolam, with a washout period of at least 5 days between treatments. The 50-mg/mL IN midazolam formulation consisted of 5 mg midazolam base per 0.1 mL (1 spray) and was administered once in 1 nostril. The IV midazolam solution (2.5 mg) was infused over 10 seconds. Blood samples were taken before and at regular intervals up to 240 minutes after dosing. Pharmacokinetic data (ie, C(max), T(max), t(½), and AUC) were analyzed using a 2-compartment model.

RESULTS

Of 9 volunteers screened and enrolled, 7 completed the study (mean age 34.1 [9.0] years; mean weight, 68.6 [10.4] kg, range 53-89 kg; 6 men, 3 women; all white). The mean C(max) of 78 (40) ng/mL was reached 44 minutes after IN administration, whereas the mean C(max) was 51 (5) ng/mL after IV administration. The mean estimated C(t=5 min) was 31.4 (28.1) ng/mL after IN administration. The elimination t(½) was 1.9 (0.41) hours for IN midazolam and 2.3 (0.19) hours for IV midazolam. The bioavailability of IN midazolam was 82%. There were few adverse events, with a local burning feeling in the nose being the most reported event (6 of 7 subjects).

CONCLUSIONS

In this select group of healthy volunteers, concentrations of midazolam >30 ng/mL were reached within 5 minutes of IN administration at a dose of 5 mg/0.1 mL. A burning feeling in the nostril was the main adverse effect. Additional research is needed to evaluate the safety profile, convenience, satisfaction, and efficacy of nasal midazolam in the treatment of adults with seizures. This trial is registered at www.isrctn.org, No. ISRCTN79059168.

Use of intranasal medications in pediatric patients

A growing body of evidence supports the intranasal administration of atomized medications for a wide variety of pediatric indications. This article describes their use applicable to orthopedic specialists in the areas of pediatric pain management, as well as pre- and intraoperative sedation. As a quick, painless alternative to more invasive routes of administration, intranasal drug delivery has shown similar time to clinical effect compared to the intravenous route, while minimizing anxiety in both patients and their parents.

Pharmacokinetics and pharmacodynamics of nasally delivered midazolam

AIMS

To investigate the pharmacokinetics and pharmacodynamics of nasal formulations containing midazolam (5-30 mg ml(-1)) complexed with cyclodextrin.

METHODS

An open-label sequential trial was conducted in eight healthy subjects receiving single doses of 1 mg and 3 mg intranasally and 1 mg midazolam intravenously. Pharmacokinetic parameters were obtained by non-compartmental and two-compartmental models. Pharmacodynamic effects of midazolam were assessed using VAS and a reaction time test.

RESULTS

Mean bioavailability of midazolam after nasal administration ranged from 76 +/- 12% to 92 +/- 15%. With formulations delivering 1 mg midazolam, mean C(max) values between 28.1 +/- 9.1 and 30.1 +/- 6.6 ng ml(-1) were reached after 9.4 +/- 3.2-11.3 +/- 4.4 min. With formulations delivering 3 mg midazolam, mean C(max) values were between 68.9 +/- 19.8 and 80.6 +/- 15.2 ng ml(-1) after 7.2 +/- 0.7-13.0 +/- 4.3 min. Chitosan significantly increased C(max) and reduced t(max) of midazolam in the high-dose formulation. Mean ratios of dose-adjusted AUC after intranasal and intravenous application for 1'-hydroxymidazolam were between 0.97 +/- 0.15 and 1.06 +/- 0.24, excluding relevant gastrointestinal absorption of intranasal midazolam. The pharmacodynamic effects after the low-dose nasal formulations were comparable with those after 1 mg intravenous midazolam. The maximum increase in reaction time by the chitosan-containing formulation delivering 3 mg midazolam was greater compared with 1 mg midazolam i.v. (95 +/- 78 ms and 19 +/- 22 ms, mean difference 75.5 ms, 95% CI 15.5, 135.5, P < 0.01). Intranasal midazolam was well tolerated but caused reversible irritation of the nasal mucosa.

CONCLUSIONS

Effective midazolam serum concentrations were reached within less than 10 min after nasal application of a highly concentrated midazolam formulation containing an equimolar amount of the solubilizer RMbetaCD combined with the absorption enhancer chitosan.

A review of the clinical pharmacokinetics of opioids, benzodiazepines, and antimigraine drugs delivered intranasally

BACKGROUND

Interest in the development of drug-delivery devices that might improve treatment compliance is growing. A dosage formulation that is easy to use, such as intranasal application with transmucosal absorption, may offer advantages compared with other routes of drug delivery. The literature concerning intranasal application is diffuse, with a large number of published studies on this topic. Some cerebroactive pharmaceuticals delivered intranasally might follow the pathway from the nose to the systemic circulation to the brain. To determine the suitability of these drugs for intranasal drug delivery, a systematic review was performed.

OBJECTIVE

The aim of this review was to compare the pharmacokinetic properties of intranasal, intravenous, and oral formulations in 3 classes of cerebroactive drugs that might be suitable for intranasal delivery-opioids, benzodiazepines, and antimigraine agents.

METHODS

A search of MEDLINE, PubMed, Cumulative Index of Nursing and Allied Health Literature, EMBASE, and Cochrane Database of Systematic Reviews (dates: 1964-April 2009) was conducted for pharmacokinetic studies of drugs that might be suitable for intranasal delivery. A comparison of pharmacokinetic data was made between these 3 routes of administration.

RESULTS

A total of 45 studies were included in this review. Most of the opioids formulated as an intranasal spray reached a T(max) within 25 minutes. The bioavailability of intranasal opioids was high; in general, >50% compared with opioids administered intravenously. Intranasal benzodiazepines had an overall T(max) that varied from 10 to 25 minutes, and bioavailability was between 38% and 98%. T(max) for most intranasal antimigraine drugs varied from 25 to 90 minutes. Intranasal bioavailability varied from 5% to 40%.

CONCLUSIONS

This review found that intranasal administration of all 3 classes of drugs was suitable for indications of rapid delivery, and that the pharmacokinetic properties differed between the intranasal, oral, and intravenous formulations (intravenous > intranasal > oral).

Attenuation of kindled seizures by intranasal delivery of neuropeptide-loaded nanoparticles

Thyrotropin-releasing hormone (TRH; Protirelin), an endogenous neuropeptide, is known to have anticonvulsant effects in animal seizure models and certain intractable epileptic patients. Its duration of action, however, is limited by rapid tissue metabolism and the blood-brain barrier. Direct nose-to-brain delivery of neuropeptides in sustained-release biodegradable nanoparticles (NPs) is a promising mode of therapy for enhancing CNS neuropeptide bioavailability. To provide proof of principle for this delivery approach, we used the kindling model of temporal lobe epilepsy to show that 1) TRH-loaded copolymer microdisks implanted in a seizure focus can attenuate kindling development in terms of behavioral stage, afterdischarge duration (ADD), and clonus duration; 2) intranasal administration of an unprotected TRH analog can acutely suppress fully kindled seizures in a concentration-dependent manner in terms of ADD and seizure stage; and 3) intranasal administration of polylactide nanoparticles (PLA-NPs) containing TRH (TRH-NPs) can impede kindling development in terms of behavioral stage, ADD, and clonus duration. Additionally, we used intranasal delivery of fluorescent dye-loaded PLA-NPs in rats and application of dye-loaded or dye-attached NPs to cortical neurons in culture to demonstrate NP uptake and distribution over time in vivo and in vitro respectively. Also, a nanoparticle immunostaining method was developed as a procedure for directly visualizing the tissue level and distribution of neuropeptide-loaded nanoparticles. Collectively, the data provide proof of concept for intranasal delivery of TRH-NPs as a viable means to 1) suppress seizures and perhaps epileptogenesis and 2) become the lead compound for intranasal anticonvulsant nanoparticle therapeutics.