The pharmacokinetics of intravenous, intramuscular, and subcutaneous nalbuphine in healthy subjects

A Continuous Intestinal Absorption Model to Predict Drug Enterohepatic Recirculation in Healthy Humans: Nalbuphine as a Model Substrate

Nalbuphine (NAL) is a κ-agonist/μ-antagonist opioid being developed as an oral extended formulation (ER) for the treatment of chronic cough in idiopathic pulmonary fibrosis and itch in prurigo nodularis. NAL is extensively glucuronidated and likely undergoes enterohepatic recirculation (EHR). The purpose of this work is to develop pharmacokinetic models for NAL absorption and enterohepatic recirculation (EHR). Clinical pharmacokinetic (PK) data sets in healthy subjects from three trials that included IV, oral solution, and ER tablets in fed and fasted state and two published trials were used to parametrize a novel partial differential equation (PDE)-based model, termed "PDE-EHR" model. Experimental inputs included in vitro dissolution and permeability data. The model incorporates a continuous intestinal absorption framework, explicit liver and gall bladder compartments, and compartments for systemic drug disposition. The model was fully PDE-based with well-stirred compartments achieved by rapid diffusion. The PDE-EHR model accurately reproduces NAL concentration-time profiles for all clinical data sets. NAL disposition simulations required inclusion of both parent and glucuronide recirculation. Inclusion of intestinal P-glycoprotein efflux in the simulations suggests that NAL is not expected to be a victim or perpetrator of P-glycoprotein-mediated drug interactions. The PDE-EHR model is a novel tool to predict EHR and food/formulation effects on drug PK. The results strongly suggest that even intravenous dosing studies be conducted in fasted subjects when EHR is suspected. The modeling effort is expected to aid in improved prediction of dosing regimens and drug disposition in patient populations.

Comparative pharmacokinetics of nalbuphine nasal spray and solution for injection in healthy volunteers

AIMS

Nalbuphine is a synthetic opioid with comparable analgesic activity to morphine but with a better safety profile. Nalbuphine is only available in injectable form due to low oral bioavailability. Nasal nalbuphine spray provides advantages in drug safety, avoids hepatic first-pass metabolism, is non-invasive and is convenient for patient-controlled analgesia by self-administration. This study aimed to evaluate the safety and pharmacokinetics (PK) of the newly developed nalbuphine nasal spray in comparison with a solution for injections.

METHODS

Twenty-four healthy Caucasian volunteers were enrolled in this randomized, open-label, cross-over study. Subjects were administered one of the drugs: nasal spray 7.0 mg/dose, nalbuphine hydrochloride solution for injection 10 mg/dose intravenously (IV) or intramuscularly (IM). High-performance liquid chromatography-tandem mass spectrometry was used to determine nalbuphine concentrations.

RESULTS

A comparison of PK profiles for IV, IM and intranasal (IN) routes of nalbuphine administration revealed a close similarity of absorption phases for nasal spray and IM injection. Differences between the mean Tmax and dose-adjusted Cmax values for nasal spray and IM injection were statistically insignificant. The median values of the elimination rate constants and the terminal elimination half-life following IV, IM and IN nalbuphine administration were similar. The mean absolute bioavailability of the nasal spray equalled 65.04%.

CONCLUSIONS

The similarity of PK parameters of IM-injected nalbuphine solution and the nasal spray allows us to assume the latter is a feasible alternative to intramuscular nalbuphine injections appropriate for self-administration and field environments for managing moderate and severe pain of various aetiologies.

What Parenteral Opioids to Use in Face of Shortages of Morphine, Hydromorphone, and Fentanyl

Parenteral potent opioid availability is becoming an issue in acute pain management. Two opioids, nalbuphine and buprenorphine, are available which can be substituted for hydromorphone, fentanyl, and morphine. There are advantages and disadvantages in using these 2 opioids which are discussed, and potential dosing strategies are outlined.

Sebacoyl Dinalbuphine Ester Extended-release Injection for Long-acting Analgesia: A Multicenter, Randomized, Double-Blind, And Placebo-controlled Study in Hemorrhoidectomy Patients

OBJECTIVES

This study was conducted to evaluate the safety and efficacy of single sebacoyl dinalbuphine ester (SDE) injection (150 mg/2 mL) when administered intramuscularly to patients who underwent hemorrhoidectomy for postoperative long-acting analgesia.

METHODS

A total of 221 patients scheduled for hemorrhoidectomy from 6 centers in Taiwan were randomly divided into SDE group and placebo group, and received the treatment, vehicle or SDE, 1 day before the surgery. Visual analogue scale (VAS) was recorded up to 7 to 10 days. Pain intensity using VAS AUC through 48 hours after surgery was calculated as the primary efficacy endpoint.

RESULTS

Area under the curve of VAS pain intensity scores (VAS AUC) through 48 hours after hemorrhoidectomy was significantly less in SDE group than those in placebo group (209.93 vs. 253.53). VAS AUC from the end of surgical procedure to day 7 was also significantly different between SDE and placebo group (630.79 vs. 749.94). SDE group consumed significantly less amount of other analgesics, such as PCA ketorolac and oral ketorolac. Median time from the end of surgery to the first use of pain relief medication was also shortened in the placebo group than in the SDE group. Most adverse events were assessed as mild and tolerable in both groups.

DISCUSSION

SDE injection demonstrated an extended analgesia effect, with a statistically significant reduction in pain intensity through 48 hours and 7 days after hemorrhoidectomy.

Pharmacokinetics and effect of intravenous nalbuphine in weaned Holstein calves after surgical castration

The objective of this study was to investigate the pharmacokinetics and effect of nalbuphine administered intravenously to calves immediately prior to surgical castration. Ten healthy calves were randomly assigned to two treatments (n = 5): (i) 0.9% sodium chloride (CONT) placebo, (ii) nalbuphine hydrochloride (NAL) (0.4 mg/kg). Blood samples collected over 10 h postcastration were analyzed for nalbuphine and cortisol concentrations. Additionally, heart rate, respiratory rate, rectal temperature, and step count was compared between groups using a random-effects mixed model. Changes in behavior and attitude were assessed using a six-point ordinal scoring system and compared using chi-square analysis. Plasma NAL concentrations were only detectable for 3 h postadministration (T½ = 0.68 h; Range: 0.53-0.79 h). There was no effect of NAL treatment prior to castration on cortisol concentrations (P = 0.99), heart rate (P = 0.73), respiratory rate (P = 0.59), rectal temperature (P = 0.22), and step count (P = 0.08) but fewer calves showed signs of head shaking, kicking, and tail flicking in the NAL group compared with the CONT group (P = 0.036). Therefore, we conclude that a single intravenous injection of nalbuphine at 0.4 mg/kg reduced some pain-related behaviors but did not significantly eliminate the physiological signs of distress in calves after surgical castration.

Practice efficiency and economics: the case for rapid recovery sedation agents for colonoscopy in a screening population

GOAL

To determine rapidly acting agents' impact on practice efficiency and cost for outpatient colonoscopy in a screening population.

BACKGROUND

Propofol-mediated endoscopic sedation is popular due to rapid sedation onset and superior recovery profile compared with sedation with an opioid and benzodiazepine. There are few data on the impact of this type of sedation on the economics and efficiency of an endoscopy unit.

STUDY

A provider-perspective economic model assessed the ability of propofol and fospropofol disodium (Aquavan, GPI 15715, MGI Pharma) to increase practice efficiency and determined break-even costs based on current colonoscopy reimbursement levels. Reimbursement inputs by practice setting, costs, and recovery profiles-taken from published literature examining time to discharge-were used to populate the model. To measure robustness of model results to changes in base case inputs, sensitivity analyses were performed. Using a Monte Carlo simulation, inputs were varied simultaneously and randomly for 1000 iterations to determine 95% confidence intervals (CI) for break-even costs.

RESULTS

In the time to complete 1 colonoscopy with midazolam/meperidine, 1.76 colonoscopies can be completed with propofol and 1.91 colonoscopies can be completed with fospropofol disodium. This efficiency benefit produced a break-even cost for rapid recovery agents of $71.53 (95% CI: $38.39, $105.67) in a hospital outpatient clinic and $61.48 (95% CI: $41.33, $108.99) in an ambulatory surgical center. One-way sensitivity analyses indicated the break-even cost of these agents was most sensitive to operating costs and time to discharge ratio.

CONCLUSIONS

Rapid recovery agents for colonoscopy can improve practice efficiency and offer economic advantages over traditional sedation.

Technical performance of colonoscopy in patients sedated with nurse-administered propofol

OBJECTIVES

Nurse-administered propofol has gained attention as a safe and effective means of sedation for patients undergoing endoscopic procedures. However, little is known about the effect of propofol on the technical performance of colonoscopy.

METHODS

Three separate studies were conducted. In the first study, we reviewed procedure notes from consecutive colonoscopies performed by a single experienced endoscopist at our hospital endoscopy unit on patients sedated with either nurse-administered propofol (n = 162) or midazolam/narcotic (n = 164). In the second study, 100 eligible colonoscopy outpatients were randomized to receive either nurse-administered propofol (n = 50) or midazolam/fentanyl (n = 50). In both studies, the measured parameters included visualization of the cecum, time required to reach the cecum, repositioning of the patient, and the application of abdominal counterpressure. In a third study, we reviewed the rate of cecal intubation and colonic perforation in the first 2357 patients in our unit receiving nurse-administered propofol.

RESULTS

In the retrospective comparative study, there was no difference in the cecal intubation rate in those receiving propofol (99.4%) compared to those receiving midazolam/narcotic (97%; p= 0.1), and three of five failed cecal intubations in the latter group resulted from obstructing masses. Patients sedated with propofol were repositioned less frequently compared to those receiving midazolam/narcotic (3.7%vs 26.2%) (p < 0.0001). Abdominal pressure was employed in 9.9% of patients sedated with propofol compared to 19.5% (p= 0.01) of those given midazolam/narcotic. The mean time to reach the cecum was lower in the propofol group than in the midazolam/narcotic group (4.6 min vs 6.0 min, p= 0.002). In the prospective randomized study, the endoscopist intubated the cecum in all 100 patients. Patients in the propofol group were repositioned less frequently than those in the midazolam/fentanyl group (2%vs 24%, respectively, p= 0.001). The number of cases requiring abdominal counterpressure was not significantly different between the propofol and midazolam/fentanyl groups (12%vs 24%, respectively, p= 0.1). The mean time to reach the cecum in the propofol group (3.2 min) was similar to that in the midazolam/fentanyl group (3.8 min, p= 0.08). Among the first 2357 patients in our unit undergoing colonoscopy with nurse-administered propofol, the rate of complete colonoscopy was 99.2% and there were no perforations.

CONCLUSION

Nurse-administered propofol sedation is safe and simplifies the technical performance of colonoscopy compared to midazolam/narcotic sedation.

Pharmacokinetics of intrarectal nalbuphine in children undergoing general anaesthesia

The pharmacokinetics of nalbuphine (0.3 mg/kg) administered by the rectal route were studied in ten children undergoing general anaesthesia for minor surgery. Blood sampling was carried out for 8 h after rectal administration and plasma drug concentrations were measured by high performance liquid chromatography using electrochemical detection after an optimized solid-phase extraction procedure. The mean time to achieve the maximum plasma concentration (Cmax = 24 +/- 15 ng/mL) was 25 +/- 11 min and the elimination half-life was 2.7 +/- 0.7 h. The coefficients of variation for Cmax and the concentration-time curve (AUC) were 62 and 68%, respectively. Although rectal absorption is considered irregular, the large intersubject variability is also explainable by a variable hepatic bypass for a drug, like nalbuphine, that undergoes extensive first-pass metabolism. No problem of analgesic efficacy or of local tolerance was reported. In conclusion, the rectal route of administration provides a rapid and reliable absorption of nalbuphine.

The effect of aging on the pharmacokinetics of nalbuphine in rabbits

For the purpose of selecting an animal model for the study of the aging effect on the pharmacokinetics of nalbuphine, the pharmacokinetic properties in young and in aged rabbits were reported. Thirty-one healthy New Zealand white rabbits ranging in ages (mean) from three months to 43 months (six three months old, group I; nine eight months old, group II; nine 18 months old, group III; and seven 43 months old, group IV) were included in the study. After intravenous bolus injection of nalbuphine (10 mg kg-1) to each rabbit, plasma samples were collected and analysed for nalbuphine by a high-performance liquid chromatography method. The plasma concentration-time data regarding nalbuphine were successfully fitted to a linear two-compartment open model. The elimination half-life of nalbuphine in rabbits increased significantly with age. Consequently, clearance decreased significantly with age. The parameter AUCO-affinity, which is derived from dose/clearance, increased significantly with age. The effect of aging on the pharmacokinetics of nalbuphine in rabbits is quite similar to that in humans. From the present study, it is concluded that rabbits may be suitable for the study of aging effects on the pharmacokinetics of nalbuphine.

A dose-response study of nalbuphine for post-thoracotomy epidural analgesia

The analgesic efficacy and side-effects of epidural nalbuphine (0.075-0.3 mg.kg-1) were compared with epidural morphine 0.1 mg.kg-1 in a randomised double-blind study in post-thoracotomy patients. The drugs were administered via a lumbar epidural catheter one hour before the end of surgery. Efficacy was assessed using visual analogue pain scores and supplementary iv fentanyl requirements; respiratory function was studied with an inductive plethysmograph and arterial blood gas analysis; and plasma nalbuphine levels were measured. Pain scores and fentanyl supplementation were lowest in the morphine group (P less than 0.01). No dose-response effect was apparent in the nalbuphine dose-range studied. Respiratory depression was more common in patients receiving morphine (higher mean PaCO2P less than 0.01, more frequent apnoeas greater than 15 sec P less than 0.05, and incidence of PaCO2 greater than 50 mmHg requiring naloxone P less than 0.01). There were no differences in haemodynamic variables, sedation, or other side-effects among the groups. The pharmacokinetic profile of epidural nalbuphine was similar to that seen with rapid iv injection. The results indicate that, relative to morphine, lumbar epidural nalbuphine is an ineffective analgesic after thoracotomy. Despite the lower incidence of respiratory depression its administration by this route cannot be recommended.

Psychomotor, respiratory and neuroendocrinological effects of nalbuphine and haloperidol, alone and in combination, in healthy subjects

1. Actions and interactions on performance and respiration of single intramuscular doses of 0.15 mg kg-1 nalbuphine and oral haloperidol twice daily for 2 days were studied double-blind and cross-over in 12 healthy volunteers. 2. Objective measurements of performance (choice reaction, tracking, attention, flicker fusion, Maddox wing, digit symbol substitution) and respiratory function (minute volume, end-tidal carbon dioxide), and subjective assessments on visual analogue scales were done at baseline and 1 h, 2.5 h and 4 h after the injection of nalbuphine. Plasma concentrations of nalbuphine were estimated by radioreceptor ([3H]-dihydromorphine) assay, and those of prolactin and growth hormone by radioimmunoassay. 3. Nalbuphine affected digit substitution, reaction time, extraocular muscle balance and flicker recognition, and depressed respiration most clearly 1 and 2.5 h post injection. Motor skills were impaired only briefly. Haloperidol alone proved inert on performance but enhanced the decremental effects of nalbuphine on digit substitution and exophoria at 1 h. It did not interact with nalbuphine on the ventilatory function. 4. Plasma concentrations of nalbuphine expressed as morphine equivalents ranged from 5 to 52 ng ml-1, indicating considerable mu-opiate affinity. Treatment with haloperidol increased plasma prolactin moderately whilst nalbuphine raised it markedly 1 and 2.5 h post injection. Nalbuphine elevated plasma growth hormone at 1 h post injection only.