Pharmacokinetics of oral triazolam in children

Expanded studies of the pharmacokinetics and clinical effects of multidose sublingual triazolam in healthy volunteers

Previous work described the pharmacokinetics and clinical effects of multidose sublingual triazolam (Halcion; Pharmacia & Upjohn Co, Kalamazoo, Mich). This laboratory study evaluated the hypothesis that incremental dosing of triazolam produces dose-dependent central nervous system depression that is profound and long lasting. Forty-nine healthy adults between the ages of 21 and 39 years, not receiving dental treatment, were randomly assigned to placebo (n = 12) or 1 of 3 triazolam groups (0.25-mg single dose, n = 12; 0.5 mg divided between 2 equal doses for 60 minutes, n = 12; or 0.75 mg divided among 3 doses for 90 minutes, n = 13). Plasma triazolam concentrations were determined. Bispectral index (BIS) and the Observer Assessment of Alertness/Sedation scale were used to assess sedation. Plasma triazolam concentrations increased with time in all subjects, with Tmax and Cmax both increasing dose dependently. Compared with placebo, all dosing paradigms produced dose-dependent BIS suppression and sedation. The single dose of 0.25 mg reached its peak BIS suppression at 90 (81 +/- 7) minutes and sedation at 120 (3.6 +/- 0.5) minutes and returned to baseline before 360 minutes. In contrast, incremental dosing of 0.5 and 0.75 mg produced profound and long-lasting BIS suppression and sedation that did not plateau until either 180 or 210 minutes as measured by the BIS index (67 +/- 14 and 60 +/- 16 at 0.5 and 0.75 mg, respectively) and 150 minutes as measured by the Observer Assessment of Alertness/Sedation scale (3.2 +/- 1.0 and 2.7 +/- 0.4 at 0.5 and 0.75 mg, respectively). These data more fully characterize the effects of incremental dosing with sublingual triazolam and provide additional insight for discharge safety recommendations.

Pharmacokinetics and clinical effects of multidose sublingual triazolam in healthy volunteers

Triazolam is increasing in popularity as a premedication prescribed by dentists to help their fearful and anxious patients tolerate the potentially aversive nature of some dental procedures. Recent anecdotal reports suggest that incremental sublingual dosing of triazolam may be an effective technique for producing conscious sedation in the dental setting. Although promising, no laboratory or clinical data have been available to evaluate the efficacy or safety of this approach. This study was designed to determine the pharmacokinetics and sedative effects of incremental sublingual dosing of triazolam (total, 1.0 mg) in healthy adults. Ten healthy adult volunteers received sublingual triazolam (0.25 mg) followed by additional doses after 60 (0.50 mg) and 90 (0.25 mg) minutes. Plasma triazolam concentrations, clinical effects (Observer's Assessment of Alertness/Sedation score), and processed electroencephalogram (bispectral index score) were measured intermittently for 3 hours. Plasma triazolam concentrations (mean +/- SD, 5.1 +/- 1.1 ng/mL) and drug effects (Observer's Assessment of Alertness/Sedation score, 2 +/- 1; and the bispectral index score, 62 +/- 16) were greatest in all subjects at the end of the 3-hour evaluation period. Eight of the subjects had Observer's Assessment of Alertness/Sedation scores consistent with the definition of deep sedation or general anesthesia (Observer's Assessment of Alertness/Sedation score, <3) at some of the later time points in the 180 minutes of data collection. In comparison, 4 of the subjects had bispectral index scores less than 60 during these later time points of data collection. Given the considerable intersubject variability in triazolam concentrations and effects, additional research is needed to assess this multidosing strategy before it can be endorsed as a useful and safe sedation technique for managing fearful and anxious patients in dental practice.

Human variability in CYP3A4 metabolism and CYP3A4-related uncertainty factors for risk assessment

CYP3A4 constitutes the major liver cytochrome P450 isoenzyme and is responsible for the oxidation of more than 50% of all known drugs. Human variability in kinetics for this pathway has been quantified using a database of 15 compounds metabolised extensively (>60%) by this CYP isoform in order to develop CYP3A4-related uncertainty factors for the risk assessment of environmental contaminants handled via this route. Data were analysed from published pharmacokinetic studies (after oral and intravenous dosing) in healthy adults and other subgroups using parameters relating primarily to chronic exposure [metabolic and total clearances, area under the plasma concentration-time curve (AUC)] and acute exposure (Cmax). Interindividual variability in kinetics was greater for the oral route (46%, 12 compounds) than for the intravenous route (32%, 14 compounds). The physiological and molecular basis for the difference between these two routes of exposure is discussed. In relation to the uncertainty factors used for risk assessment, the default kinetic factor of 3.16 would be adequate for adults, whereas a CYP3A4-related factor of 12 would be required to cover up to 99% of neonates, which have lower CYP3A4 activity.

Pharmacokinetics and clinical effects of sublingual triazolam in pediatric dental patients

The purpose of this investigation was to describe the pharmacokinetics of sublingual triazolam in children. Nine healthy children (64-98 months old) received 0.25 or 0.375 mg of sublingual triazolam before dental treatment. Plasma triazolam concentrations were measured by gas chromatography/mass spectrometry and analyzed by noncompartmental methods. The peak concentration was 4.9 +/- 2.0 ng/mL (mean +/- SD), time to peak was 75 +/- 32 minutes, the elimination half-life was 91 +/- 32 minutes, and apparent clearance was 17.6 +/- 8.8 mL x kg(-1) x min(-1). Children were tested for gait ataxia, amnesia, and diplopia during a screening session and again after triazolam. Ninety minutes after drug administration, seven of nine children demonstrated ataxia, and three of nine demonstrated amnesia. Peak triazolam concentrations were similar in children with or without ataxia, but they were significantly higher in children with amnesia compared with those without amnesia. Six children demonstrated diplopia 30 and 120 minutes after triazolam; however, peak triazolam concentrations were similar in both groups. Sublingual administration was an acceptable alternative route of triazolam delivery in children.

A randomized clinical trial of triazolam in 3- to 5-year-olds

Triazolam has shown promise as a sedative agent for use in pediatric dentistry. However, the efficacy of triazolam has not been previously examined in a placebo-controlled study. The present clinical trial used a two-group, randomized, double-blind study design to compare the efficacy of oral triazolam with that of a placebo. The primary hypothesis tested was that triazolam would reduce negative behaviors of pediatric dental patients compared with a placebo. A secondary hypothesis was that triazolam would increase the efficiency of dental treatment by reducing the need for time-consuming behavior management by the pediatric dentist. The subjects were 54 3- to 5-year-old children, randomly assigned to the drug and placebo groups. The active drug, 0.03 mg/kg triazolam (Halcion), or lactose placebo was given orally 30 min before dental treatment. Behavior management techniques commonly used in pediatric dentistry were used during dental treatment. A single pediatric dentist provided all of the dental treatment. The procedure included an inferior block anesthesia and careful attention to anesthesia effectiveness. All sessions were video-taped and the tapes coded for child and dentist behaviors by an independent observer. There were no statistically significant differences between the groups with respect to completion of dental treatment. There were no significant differences found in either the total time or the percent of time that the subjects exhibited disruptive movements, verbal or non-verbal distress. The total use of time in the dental chair was slightly higher in the placebo than in the drug group due to more time spent preparing the child. Contrary to preliminary reports in the literature, this investigation found little or no improvement in child behavior when triazolam was used as a sedative compared with a placebo. However, triazolam did shorten the length of dental treatment, primarily by reducing dentist time in preparing the child for the dental procedure (e.g., establishing rapport and shaping behavior).