Sublingual absorption of selected opioid analgesics

Early emergency department experience with 7-day extended-release injectable buprenorphine for opioid use disorder

As the opioid overdose epidemic escalates, there is an urgent need for treatment innovations to address both patient and clinician barriers when initiating buprenorphine in the emergency department (ED). These include insurance status, logistical challenges such as the ability to fill a prescription and transportation, concerns regarding diversion, and availability of urgent referral sites. Extended-release buprenorphine (XR-BUP) preparations such as a new 7-day injectable could potentially solve some of these issues. We describe the pharmacokinetics of a new 7-day XR-BUP formulation and the feasibility of its use in the ED setting. We report our early experiences with this medication (investigational drug CAM2038), in the context of an ongoing clinical trial entitled Emergency Department-Initiated BUP VAlidaTION (ED INNOVATION), to inform emergency clinicians as they consider incorporating this medication into their practice. The medication was approved by the European Medicines Agency in 2018 and the U.S. Food and Drug Administration in 2023 for those 18 years or older for the treatment of moderate to severe opioid use disorder (OUD). We report our experience with approximately 800 ED patients with OUD who received the 7-day XR-BUP preparation in the ED between June 2020 and July 2023.

Improving the Emergency Department Management of Sickle Cell Vaso-Occlusive Pain Crisis: The Role and Options of Sublingual and Intranasally Administered Analgesia

Vaso-occlusive crisis (VOC), characterized by periods of excruciating pain is the most common clinical manifestation of sickle cell disease (SCD), often resulting in emergency room presentation. These patients often experience long wait times in the emergency department before receiving their first dose of analgesia. This delay results from the complexities of the emergency care system. Using the intranasal or sublingual approach to administering analgesia to SCD patients with VOC offers a fast, safe, noninvasive, atraumatic, and easily accessible route of administration which could reduce the time to first dose of analgesia. With the evolving advances in the development and delivery of analgesic medications, providers should be conversant with the nuances of intranasal and sublingual analgesia in the management of acute vaso-occlusive pain crisis. This review explores the pharmacokinetic profiles, dosages, and administration of intranasal and sublingual analgesics with relevance to the SCD population.

Pharmacokinetic considerations for community-based dosing of nasal naloxone in opioid overdose in adults

INTRODUCTION

The administration of the opioid antagonist naloxone in the community is a measure to prevent death from opioid overdose. Approved nasal naloxone sprays deliver initial doses of 0.9 to 8 mg. The level of the initial community dose is controversial, as the scientific base is weak.In this review knowledge of the pharmacokinetics of nasal, both approved and improvised nasal sprays, and intramuscular naloxone will be utilized to evaluate dose-effect relationships in previous studies of opioid overdose outcomes.

AREAS COVERED

The aim was to present scientifically based considerations on the initial nasal naloxone doses currently available, which reasonably balances the effect and adverse outcomes, given that at least two doses are at hand. Also included in these considerations is the challenge by illicitly manufactured fentanyl and analogs.This paper is based on both peer-reviewed and grey literature identified by several searches, of such as naloxone pharmacokinetics/formulations/outcomes/emergency medical services, in PubMed and Embase.

EXPERT OPINION

There is little scientific evidence that supports the use of initial systemic dosing that exceeds 0.8 mg in the community. Higher doses increase the risk of withdrawal symptoms feared in people who use opioids. Many obstacles may reduce the potential of community-administered naloxone.

Sublingual Versus Swallowed Morphine: A Comparison

BACKGROUND

The optimal route for immediate-release morphine administration is controversial. The known physical characteristics of morphine that allow absorption are counter to the unproven belief that sublingual morphine is absorbed more quickly.

OBJECTIVE

The aim of this study was to compare swallowed and sublingual morphine for effects on plasma morphine concentrations (PMCs), pain relief, and taste.

METHODS

Ten participants with cancer (mean age, 50 ± 12 years) received a 10-mg morphine tablet in a randomized crossover design with repeated premeasure and postmeasure for 60 minutes. Measures included PMC and visual analog scale (100 mm) scores for pain relief and taste.

RESULTS

Interindividual variability in maximum PMC was 25-fold (2.2-55 ng/mL). At 60 minutes, sublingual and swallowed routes were not significantly different for mean area under the curve for PMC (swallowed, 329 ± 314 ng/mL; sublingual, 314 ± 299 ng/mL) or for mean pain relief scores (swallowed, 81 ± 32; sublingual, 78 ± 31). Taste scores at 5 (P < .05), 10 (P < .04), 15 (P < .02), and 20 (P < .04) minutes after swallowed doses were significantly less unpleasant than after sublingual doses.

CONCLUSION

In this crossover design, between-group PMCs were similar for sublingual and swallowed morphine and resulted in a similar level of pain relief. Given the 25-fold across-participant differences in PMC after the same dose, additional research is warranted to identify the sources of this tremendous variability in PMC.

IMPLICATIONS FOR PRACTICE

Because of unpleasant taste, which could influence adherence and subsequent analgesia, clinicians should encourage patients to swallow their morphine doses and restrict use of sublingual morphine to individuals who are unable to swallow.

Clinical pharmacology and dosing regimen optimization of neonatal opioid withdrawal syndrome treatments

In this paper, we review the management of neonatal opioid withdrawal syndrome (NOWS) and clinical pharmacology of primary treatment agents in NOWS, including morphine, methadone, buprenorphine, clonidine, and phenobarbital. Pharmacologic treatment strategies in NOWS have been mostly empirical, and heterogeneity in dosing regimens adds to the difficulty of extrapolating study results to broader patient populations. As population pharmacokinetics (PKs) of pharmacologic agents in NOWS become more well‐defined and knowledge of patient‐specific factors affecting treatment outcomes continue to accumulate, PK/pharmacodynamic modeling and simulation will be powerful tools to aid the design of optimal dosing regimens at the patient level. Although there is an increasing number of clinical trials on the comparative efficacy of treatment agents in NOWS, here, we also draw attention to the importance of optimizing the dosing regimen, which can be arguably equally important at identifying the optimal treatment agent.

Buccal Hydromorphone Syrup for Managing Dyspnea in Idiopathic Pulmonary Fibrosis

Context:

Dyspnea is a highly distressing symptom that characterizes idiopathic pulmonary fibrosis (IPF), a common idiopathic interstitial lung disease (ILD) with a high symptom burden, poor quality of life, and early mortality. Though opioids are mentioned in guidelines for dyspnea management, guidance on how and when to initiate opioids is lacking. Different pharmacologic strategies are needed to address different types of dyspnea (baseline, incident, and crisis). Due to a longer onset of action, the oral route (swallowed) may be less effective for prevention of incident dyspnea or for rapid relief of crisis dyspnea, prompting the use of alternative drug delivery strategies for self-management. We inadvertently discovered the efficacy of buccal administration of low dose, low volume hydromorphone oral syrup for dyspnea management in ILD, which has not been previously reported in the literature.

Case Series:

We describe our approach to dyspnea assessment and management in IPF, including use of the Multidimensional Dyspnea Scale (MDDS), a novel instrument yet to be validated that we developed to better identify and categorize dyspnea into the types experienced by a patient with IPF over the course of a day. We then describe how buccal hydromorphone oral syrup is initiated and titrated for dyspnea management in 3 patients at different points in their disease trajectory.

Conclusion:

Buccal hydromorphone oral syrup is effective for dyspnea management across the spectrum of IPF. When integrated into a patient-centered algorithm for symptom assessment and management, it allows for rapid and easy self-management of dyspnea by patients and their caregivers.

Pharmacotherapy of neonatal opioid withdrawal syndrome: a review of pharmacokinetics and pharmacodynamics

INTRODUCTION

Neonatal opioid withdrawal syndrome (NOWS) often arises in infants born to mothers who used opioids during pregnancy. Morphine, methadone, and buprenorphine are the most common first-line treatments, whereas clonidine and phenobarbital are generally reserved for adjunctive therapy. These drugs exhibit substantial pharmacokinetic (PK) and pharmacodynamic (PD) variability. Current pharmacological treatments for NOWS are based on institutional protocols and largely rely on empirical treatment of patient symptoms.

AREAS COVERED

This article reviews the PK/PD of NOWS pharmacotherapies with a focus on the implication of physiological development and maturation. Body size-standardized clearance is consistently low in neonates, except for methadone. This can be ascribed to underdeveloped metabolic and elimination pathways. The effects of pharmacogenetics have been clarified especially for morphine. The PK/PD relationship of medications used in the treatment of NOWS is generally understudied.

EXPERT OPINION

Providing an appropriate opioid dose in neonates is challenging. Advancements in quantitative pharmacology and PK/PD modeling approaches facilitate identification of key factors driving PK/PD variability and characterization of exposure-response relationships. PK/PD model-informed simulations have been widely employed to define age-appropriate pediatric dosing regimens. The model-informed approach holds promise to aid more rational use of medications in the treatment of NOWS.

Sexual dysfunction in men on buprenorphine - naloxone-based substitution therapy

BACKGROUND

The literature on sexual dysfunction in patients on buprenorphine-naloxone (BNX) substitution is limited.

MATERIALS AND METHODS

This research aimed to study the prevalence and correlates of sexual dysfunction in men on BNX substitution therapy. We recruited consecutive forty men from BNX clinic, who had received BNX for at least 6 months, who were free from any recent illicit drug use (confirmed by urine chromatographic immune assay), and who were either married or had a stable sexual partner. Men with other psychiatric and substance use disorders (except tobacco) were excluded from the study. Data for the control group were obtained from a published study (with similar selection criteria) from our center. We assessed sexual dysfunction with two cross-culturally validated instruments: Arizona Sexual Experience Scale (ASEX) and International Index of Erectile Function.

RESULTS

The sample had a mean age of 31.6 (±8) years; the mean duration of BNX treatment was 9 (±4.2) months and the mean BNX dose was 4.5 (±1.6) mg. ASEX showed the prevalence of sexual dysfunction to be 40%. The IIEF demonstrated intercourse dissatisfaction (95%) and hypoactive sexual desire (92.5%) as almost universal, while 77.5% of the participants reported erectile dysfunction. In comparison to the published data, these figures were significantly more than among the controls. We found no correlation of sexual dysfunction with marital status, age, duration or dose of BNX, duration of illicit opioid use, the severity of opioid dependence, and tobacco dependence.

CONCLUSION

All men on BNX maintenance therapy must be screened for sexual dysfunction. With the rapid scaling up of office-based BNX substitution, assessment and management of sexual dysfunction ought to be incorporated in the training curriculum.

Oral morphine drops for prompt relief of breathlessness in patients with advanced cancer-a randomized, double blinded, crossover trial of morphine sulfate oral drops vs. morphine hydrochloride drops with ethanol (red morphine drops)

PURPOSE

Episodic breathlessness is frequent in palliative cancer patients. Opioids are the only pharmacological agents with sufficient evidence in treatment. In Denmark, the main recommendation is red morphine drops (RMD), an off-label solution of morphine, ethanol, and red color (cochenille) described since 1893 (Pharmacopoea Danica). In 2015, the Danish Medicines Agency increased focus on off-label medicines and recommended registered morphine drops without ethanol instead. However, our palliative patients told us that RMD was better. For that reason, we conducted a clinical trial to clarify any perceived difference between the two types of drops.

METHODS

We conducted a randomized, double blinded, crossover trial. Patients were asked to perform standardized activity (2-min walk) aiming to provoke breathlessness. Primary endpoint (breathlessness NRS) and secondary endpoints (saturation, pulse, respiratory frequency) were measured before (t = 0) and after test medicine at t = 1, t = 3, t = 5, t = 10, and t = 20 min. After 2-4 days (washout period), the patients repeated the test, receiving the alternative drops in a blinded setup (crossover).

RESULTS

In the first 3 min, the relative drop in breathlessness for morphine drops with ethanol (RMD) was significant more than for morphine drops without ethanol. We found no significant difference in secondary endpoints.

CONCLUSIONS

A conclusion could be that ethanol might facilitate morphine absorption in the mouth. Our results needs further research of opioid absorption in the mouth as well as trials, testing morphine vs. more lipophilic opioids. The RMD drops are cheap, easy to use, and noninvasive and keep the patient independent of health care professionals.

Characterization of the Pharmacokinetics of Samidorphan in Healthy Volunteers: Absolute Bioavailability and the Effect of Food and Age

BACKGROUND AND OBJECTIVES

Samidorphan (SAM) is a novel μ-opioid receptor antagonist. We report clinical pharmacokinetic (PK) properties of SAM following different routes of administration, and the effects of food and age on the PK of SAM following oral administration in healthy volunteers.

METHODS

An open-label, fixed-sequence study (study 1, N = 10) examined the PK parameters following intravenous, sublingual, and oral exposure to SAM to determine absolute bioavailability. A double-blind, placebo-controlled study (study 2, N = 45) compared the PK in participants aged 18-40 years (cohort 1, n = 30) and ≥ 65 years (cohort 2, n = 15) who received a single oral dose of SAM 10 mg under fed (cohort 1 only) or fasted conditions.

RESULTS

In study 1, intravenous SAM had a plasma clearance of 33.7 L/h, volume of distribution of 341 L, and elimination half-life of 7-8 h. SAM was well-absorbed following sublingual or oral administration and reached peak concentrations (C_max) within 2 h, with absolute bioavailability of 71% (sublingual) and 69% (oral). In study 2, concentration-time profiles were similar under fed and fasted conditions (cohort 1) and for young and elderly participants from both cohorts; 90% confidence intervals for the geometric least squares mean ratios for C_max and area under the concentration-time curve from time zero extrapolated to infinity indicated equivalence.

CONCLUSIONS

SAM has high bioavailability that is comparable following sublingual and oral administration and is not subject to extensive first-pass metabolism. The PK of orally administered SAM are not affected by food or age.

Safe and Appropriate Use of Methadone in Hospice and Palliative Care: Expert Consensus White Paper

Methadone has several unique characteristics that make it an attractive option for pain relief in serious illness, but the safety of methadone has been called into question after reports of a disproportionate increase in opioid-induced deaths in recent years. The American Pain Society, College on Problems of Drug Dependence, and the Heart Rhythm Society collaborated to issue guidelines on best practices to maximize methadone safety and efficacy, but guidelines for the end-of-life scenario have not yet been developed. A panel of 15 interprofessional hospice and palliative care experts from the U.S. and Canada convened in February 2015 to evaluate the American Pain Society methadone recommendations for applicability in the hospice and palliative care setting. The goal was to develop guidelines for safe and effective management of methadone therapy in hospice and palliative care. This article represents the consensus opinion of the hospice and palliative care experts for methadone use at end of life, including guidance on appropriate candidates for methadone, detail in dosing, titration, and monitoring of patients' response to methadone therapy.

Naloxone formulation for overdose reversal preference among patients receiving opioids for pain management

BACKGROUND

Opioid-related overdose has increased 137% in the past decade. Training nonmedical bystanders to administer naloxone (Narcan™) is a widely-researched intervention that has been associated with decreases in overdose rates in the communities in which it has been implemented. A recent review advocated for noninjectable formulations of naloxone, however patient preference for naloxone formulations has not yet been examined (Strang et al., 2016).

METHODS

Two cohorts of respondents (N₁ = 501, N₂ = 172) who reported currently being prescribed an opioid for pain management were recruited through the crowd-sourcing program Amazon Mechanical Turk (MTurk) to assess their preference for naloxone formulations. All respondents were provided a description of different formulations and asked to indicate all formulations they would be willing to administer for overdose reversal and to then rank formulations in order of preference.

RESULTS

Results were remarkably similar across both cohorts. Specifically, respondents preferred noninjectable formulations (intranasal, sublingual, buccal) over injectable (intravenous, intramuscular) formulations. A small percent (8.9%-9.8%) said they would never be willing to administer naloxone. An identical percent of respondents in both cohorts (44.9%) rated intranasal as their most preferred formulation.

CONCLUSIONS

Two independent cohorts of respondents who were receiving opioid medications for pain management reported a preference for noninjectable over injectable formulations of naloxone to reverse an opioid overdose. Though initial preference is only one of many factors that impacts ultimate public acceptance and uptake of a new product, these results support the additional research and development of noninjectable naloxone formulations.

Pharmacological Treatment of Cancer Pain: Alternative Routes of Opioid Administration

Cancer-related pain is present in 51% of patients at various stages of the disease, and the incidence increases up to 74% in advanced and terminal stages. The World Health Organization proposed and issued very simple guidelines for the pharmacologic treatment of cancer-related pain. According to the guidelines, opioid analgesics are the mainstay of analgesic therapy, and the first choice for drug administration is considered to be the oral route. However, in some clinical situations, the oral route is not feasible, and analgesic drugs consequently have to be administered via an alternative route. For example, this is the case when the patient presents vomiting, bowel obstruction, severe dysphagia, mental confusion and when the opioid dose has to be increased drastically in order to achieve adequate pain control. This review of the literature is aimed at describing the indications, the limits and the main aspects of the pharmacokinetics and pharmacodynamics relative to the alternative routes of administration of opioids most commonly used in clinical practice. Sublingual, rectal, subcutaneous, intravenous, transdermal and spinal administration routes are examined.

Practical Pharmacology of Methadone: A Long-acting Opioid

Methadone is a naturally long-acting analgesic with unique pharmacodynamic and pharmacokinetic properties compared to other opioids, available now in India, to treat severe pain. It has the potential to dramatically relieve suffering among patients with serious illness who are living with persistent physical pain. However, clinicians must appreciate its unique pharmacologic properties and its use in clinical practice safely and effectively. The available formulation in India is a racemic mixture of the S- and R-enantiomers, and as such, it will have a propensity for drug-drug and drug-genetic interactions that can increase the risk of Torsades de Point and respiratory depression. Appropriate patient selection, careful dosing and thorough monitoring of methadone will mitigate these risks.

Buprenorphine in Neonatal Abstinence Syndrome

Infants exposed in utero to opioids will demonstrate a withdrawal syndrome known as neonatal abstinence syndrome (NAS). Buprenorphine is a long-acting opioid with therapeutic use in medication-assisted treatment of opioid dependency in adults and adolescents. Emerging data from clinical trials and treatment cohorts demonstrate the efficacy and safety of sublingual buprenorphine for those infants with NAS who require pharmacologic treatment. Pharmacometric modeling will assist in defining the exposure-response relationships and facilitate dose optimization.

When to Use Methadone for pain: A Case-Based Approach

The case studies are written in this article to illustrate how methadone might be used for pain in the Indian context. These cases might be used for discussion in a multidisciplinary team, or for individual study. It is important to understand that pain requires a multidisciplinary approach as opioids will assist only with physical, i.e. neuropathic and nociceptive pain, but not emotional, spiritual, or relational pain or the pain of immobility. The social determinants of pain were included to demonstrate how emotional, relational, and psychological dimensions of pain amplify the physical aspects of pain. The case studies follow a practical step-wise approach to pain while undergoing cancer treatment, pain toward the end-of-life and needing longer acting opioid. Methadone in children, and methadone in conditions of opioid toxicity or where there is a need for absorption in the proximal intestine cases are included.

Efficacy of Oral Transmucosal Fentanyl Citrate for Premedication in Patients for Surgery under General Anesthesia

Background

Oral transmucosal fentanyl citrate (OTFC), a water soluble salt when mixed in saliva is 80% nonionized; making it the only opioid suitable for transmucosal absorption. OTFC has rapid onset of action (3-5 min) with peak effect at 20-40 min and total duration of activity is 2-3 h.

Aims

This study aims to determine the efficacy of OTFC as premedicant in patients scheduled for surgery under general anesthesia (GA) and to assess the effects of OTFC on anxiety, sedation.

Settings and Design

A prospective randomized study.

Subjects and Methods

Patients between 21 and 60 years of age in American Society of Anesthesiologists physical status Classes I and II scheduled for elective surgery under GA were randomly assigned to three groups of 30 each: OTFC, placebo, and control. Mean arterial blood pressure (MAP), heart rate (HR), respiratory rate (RR), and oxygen saturation (SpO₂) along with anxiety and sedation scores were recorded as baseline and upon entering the operation theater. Adverse effects were also recorded.

Statistical Analysis Used

Statistical analysis was done using Statistical Package for Social Sciences Version 15.0 Statistical Analysis Software.

Results

No significant differences were found in MAP, HR, RR, or SpO₂ among the groups. OTFC group demonstrated significantly higher levels of anxiolysis than the control group (P < 0.05). No significant difference in sedation score was found. No remarkable adverse effects were observed.

Conclusions

OTFC is an effective anxiolytic in adult with minimal risks and side effects. It is readily acceptable by the patients in its given form.

Promoting Excellence in Symptom Management Case Series: Case Study: A New Intervention for Rapid End-of-Life Symptom Control in the Home Setting

The oral route is compromised for nearly all patients at the end of life (EOL). This article reviews the benefits and burdens of the usual alternative routes of medication delivery when the oral route fails and presents a case study on the use of a new innovation for the rectal delivery of medication to control EOL symptoms. A 62-year-old male hospice patient with end-stage metastatic prostate cancer presented with severe symptoms (Face, Legs, Activity, Cry and Consolability scale score, 9/10) that were uncontrollable with medications given via oral or sublingual routes. The patient goals were to remain at home with optimal symptom management. Rapid relief of symptoms was accomplished by the administration of medications already present in the home delivered with a new rectal catheter that provides discreet access for ongoing medication administration. Significant relief was noted within 20 minutes of dosing. The patient died peacefully 18 hours later, meeting his EOL goals, and the family was empowered to provide effective care for the patient at home. The family found the intervention easy to use. This case demonstrates how this new innovation can be used to ensure rapid symptom management and decreased burden of care by facilitating immediate and easy use of medications already present in the home.

Opioid Equivalency: A Review

Opioid analgesics are often used for the treatment of both acute and chronic pain. These agents can differ in regard to opioid receptor interactions, pharmacological actions, and side effect profiles. Furthermore, an agent can be differentiated by its relative potency and duration of action. This paper highlights the major differences between the opioid analgesics and presents a comparative table which includes equianalgesic doses for available opioid formulations. Also, guidelines for making rational prescribing decisions are discussed.

Rifampicin decreases exposure to sublingual buprenorphine in healthy subjects

Buprenorphine is mainly metabolized by the cytochrome P450 (CYP) 3A4 enzyme. The aim of this study was to evaluate the role of first‐pass metabolism in the interaction of rifampicin and analgesic doses of buprenorphine. A four‐session paired cross‐over study design was used. Twelve subjects ingested either 600 mg oral rifampicin or placebo once daily in a randomized order for 7 days. In the first part of the study, subjects were given 0.6‐mg (placebo phase) or 0.8‐mg (rifampicin phase) buprenorphine sublingually on day 7. In the second part of the study, subjects received 0.4‐mg buprenorphine intravenously. Plasma concentrations of buprenorphine and urine concentrations of buprenorphine and its primary metabolite norbuprenorphine were measured over 18 h. Adverse effects were recorded. Rifampicin decreased the mean area under the dose‐corrected plasma concentration–time curve (AUC_0–18) of sublingual buprenorphine by 25% (geometric mean ratio (GMR): 0.75; 90% confidence interval (CI) of GMR: 0.60, 0.93) and tended to decrease the bioavailability of sublingual buprenorphine, from 22% to 16% (P = 0.31). Plasma concentrations of intravenously administered buprenorphine were not influenced by rifampicin. The amount of norbuprenorphine excreted in the urine was decreased by 65% (P < 0.001) and 52% (P < 0.001) after sublingual and intravenous administration, respectively, by rifampicin. Adverse effects were frequent. Rifampicin decreases the exposure to sublingual but not intravenous buprenorphine. This can be mainly explained by an enhancement of CYP3A‐mediated first‐pass metabolism, which sublingual buprenorphine only partially bypasses. Concomitant use of rifampicin and low‐dose sublingual buprenorphine may compromise the analgesic effect of buprenorphine.

Antinociceptive effects of voluntarily ingested buprenorphine in the hot-plate test in laboratory rats

Researchers performing experiments on animals should always strive towards the refinement of experiments, minimization of stress and provision of better animal welfare. An adequate analgesic strategy is important to improve post-operative recovery and welfare in laboratory rats and mice. In addition, it is desirable to provide post-operative analgesia using methods that are minimally invasive and stressful. This study investigated the antinociceptive effects of orally administered buprenorphine ingested in Nutella® in comparison with subcutaneous buprenorphine administration. By exposing the animal to a thermal stimulus using a hot plate, significant antinociceptive effects of voluntarily ingested buprenorphine administered in Nutella® were demonstrated. This was evident at doses of 1.0 mg/kg 60 and 120 min post administration ( P < 0.01), although antinociceptive effects were not as marked as with subcutaneous administration, and had a later onset. It is advised to administer the oral formulation of buprenorphine in Nutella® in a 10-fold higher dose, as well as approximately 60 min earlier, than with the more commonly employed subcutaneous route of administration.

Perspectives on Intravenous Oxycodone for Control of Postoperative Pain

Intravenous (IV) analgesia has particular advantages in the immediate postoperative period. For example, IV administration results in a faster onset of pain relief and results in more predictable pharmacokinetics than does administration by other routes. It also allows for convenient dosing before or during surgery, permitting the initiation of effective analgesia in the early phase of the postoperative period. In addition, when patients are able to tolerate oral intake, they can be switched from IV to oral dosing based on maintaining the predictable analgesia established by the IV route. IV morphine is widely used for the control of postoperative pain, but there is a trend toward the use of oxycodone. Oxycodone (which may be mediated partly through kappa- as well as mu-opioid receptors) offers several potential advantages. Published studies comparing IV oxycodone to other IV opioids for postsurgical pain report that oxycodone is a safe and effective analgesic. Some studies show that IV oxycodone may be associated with greater pain control, fewer or less severe adverse events, and faster onset of action, although the results are not consistent across all studies. Oxycodone has been reported to be safe in the geriatric and other special populations when adequate clinical adjustments are made. Thus, the clinical reports and oxycodone's pharmacologic profile make intravenous oxycodone a potentially important "new" old drug for postoperative pain control.

Pharmacokinetics of Sublingual Buprenorphine and Naloxone in Subjects with Mild to Severe Hepatic Impairment (Child-Pugh Classes A, B, and C), in Hepatitis C Virus-Seropositive Subjects, and in Healthy Volunteers

BACKGROUND AND OBJECTIVES

Suboxone(®) is a sublingual tablet of buprenorphine/naloxone, approved for the treatment of opioid dependence. The objective of this study was to quantify the impact of hepatic impairment or hepatitis C virus infection on the pharmacokinetics of buprenorphine or naloxone and their major metabolites.

METHODS

Forty-three subjects received a single dose of a Suboxone 2.0/0.5-mg tablet. Blood samples were collected up to 168 h and pharmacokinetic parameters were calculated using non-compartmental analysis. Statistical analysis was performed using analysis of covariance.

RESULTS

Pharmacokinetic parameters were derived from 33 subjects. Compared with healthy subjects, for patients with severe hepatic impairment, total and peak exposures increased to 281.4 % [90 % confidence interval 187.1-423.3] and 171.8 % [117.9-250.2] for buprenorphine, 1401.9 % [707.6-2777.5] and 1129.8 % [577.2-2211.4] for naloxone. For moderate hepatic impaired subjects, naloxone total and peak exposure increased to 317.6 % [164.9-611.5] and 270.0  % [141.9-513.9]. For buprenorphine, only total exposure increased to 163.9 % [110.8-242.3]. Changes in maximum observed plasma concentration, area under the plasma concentration-time curve from time zero to time of the last quantifiable concentration, and area under the plasma concentration-time curve from time zero to infinity of buprenorphine or naloxone in subjects with mild hepatic impairment or with hepatitis C virus infection were within twofold of those of healthy subjects. Serious adverse events were not observed.

CONCLUSIONS

Severe and moderate hepatic impairment significantly increased exposure of naloxone and to a lesser extent of buprenorphine. Therefore, buprenorphine/naloxone combination products should generally be avoided in patients with severe hepatic impairment and may not be appropriate for patients with moderate hepatic impairment. However, buprenorphine/naloxone products may be used with caution for maintenance treatment in patients with moderate hepatic impairment who have initiated treatment on a buprenorphine product without naloxone [Registered at ClinicalTrials.gov as NCT01846455].

Canadian recommendations for the management of breakthrough cancer pain

Breakthrough cancer pain (btcp) represents an important element in the spectrum of cancer pain management. Because most btcp episodes peak in intensity within a few minutes, speed of medication onset is crucial for proper control. In Canada, several current provincial guidelines for the management of cancer pain include a brief discussion about the treatment of btcp; however, there are no uniform national recommendations for the management of btcp. That lack, accompanied by unequal access to pain medication across the country, contributes to both regional and provincial variability in the management of btcp. Currently, immediate-release oral opioids are the treatment of choice for btcp. This approach might not always offer optimal speed for onset of action and duration to match the rapid nature of an episode of btcp. Novel transmucosal fentanyl formulations might be more appropriate for some types of btcp, but limited access to such drugs hinders their use. In addition, the recognition of btcp and its proper assessment, which are crucial steps toward appropriate treatment selection, remain challenging for many health care professionals. To facilitate appropriate management of btcp, a group of prominent Canadian specialists in palliative care, oncology, and anesthesiology convened to develop a set of recommendations and suggestions to assist Canadian health care providers in the treatment of btcp and the alleviation of the suffering and discomfort experienced by adult cancer patients.

Supportive Management of Mucositis and Metabolic Derangements in Head and Neck Cancer Patients

Oral mucositis (OM) is among the most undesirable, painful, and expensive toxicities of cytotoxic cancer therapy, and is disheartening for patients and frustrating for caregivers. Accurate assessment of the incidence of OM has been elusive, but accumulating data suggests that reported OM frequency is significantly less than its actual occurrence. It has been suggested that over 90% of head and neck cancer (HNC) patients receiving radiotherapy (RT) with concurrent cisplatin experience severe OM with symptoms of extreme pain, mucosal ulceration and consequent limitations in swallowing and achieving adequate nutritional intake. This panoply of symptoms inevitably impacts a patients' quality of life and their willingness to continue treatment. In spite of all the advances made in understanding the pathophysiology of OM, there is still no prophylactic therapy with proven efficacy. Strategies to limit the extent of OM and to manage its symptomatology include basic oral care, supportive medications, nutritional support and targeting aggressive treatments to high-risk patients. This review focuses on OM recognition, preventive measurements, and symptom-management strategies.

Is levorphanol a better option than methadone?

BACKGROUND

Methadone has been a stalwart pharmacologic option for the management of opioid drug dependence for many years. It substitutes for opioid agonists and possesses certain pharmacokinetic properties that confer characteristics preferable to those of other opioids for this application. Methadone is likewise used as an option for the treatment of pain, particularly chronic pain. It has a spectrum of pharmacodynamic activity, including contributions from non-opioid components, that translates to its specific clinical attributes as an analgesic. Unfortunately, basic science studies and accumulated clinical experience with methadone have revealed some undesirable, and even worrisome, features, including issues of safety. The benefit/risk ratio of methadone might be acceptable if there was no better alternative, but neither its pharmacokinetic nor pharmacodynamic properties are unique to methadone.

OBJECTIVE

We review the basic and clinical pharmacology of methadone and suggest that levorphanol should receive attention as a possible alternative.

CONCLUSION

Unlike methadone, levorphanol is a more potent NMDA antagonist, possesses a higher affinity for DOR and KOR, has a shorter plasma half-life yet longer duration of action, has no CYP450 interactions or QTc prolongation risk, can be a viable option in the elderly, palliative care, and SCI patients, requires little to no need for co-administration of adjuvant analgesics, and has potentially a lower risk of drug-related Emergency Department visits compared to other opioids.

Buprenorphine maintenance and mu-opioid receptor availability in the treatment of opioid use disorder: implications for clinical use and policy

BACKGROUND

Sublingual formulations of buprenorphine (BUP) and BUP/naloxone have well-established pharmacokinetic and pharmacodynamic profiles, and are safe and effective for treating opioid use disorder. Since approvals of these formulations, their clinical use has increased. Yet, questions have arisen as to how BUP binding to mu-opioid receptors (μORs), the neurobiological target for this medication, relate to its clinical application. BUP produces dose- and time-related alterations of μOR availability but some clinicians express concern about whether doses higher than those needed to prevent opioid withdrawal symptoms are warranted, and policymakers consider limiting reimbursement for certain BUP dosing regimens.

METHODS

We review scientific data concerning BUP-induced changes in μOR availability and their relationship to clinical efficacy.

RESULTS

Withdrawal suppression appears to require ≤50% μOR availability, associated with BUP trough plasma concentrations ≥1 ng/mL; for most patients, this may require single daily BUP doses of 4 mg to defend against trough levels, or lower divided doses. Blockade of the reinforcing and subjective effects of typical doses of abused opioids require <20% μOR availability, associated with BUP trough plasma concentrations ≥3 ng/mL; for most individuals, this may require single daily BUP doses >16 mg, or lower divided doses. For individuals attempting to surmount this blockade with higher-than-usual doses of abused opioids, even larger BUP doses and <10% μOR availability would be required.

CONCLUSION

For these reasons, and given the complexities of studies on this issue and comorbid problems, we conclude that fixed, arbitrary limits on BUP doses in clinical care or limits on reimbursement for this care are unwarranted.

Alternative routes to oral opioid administration in palliative care: a review and clinical summary

OBJECTIVE

A major goal of palliative care is to provide comfort, and pain is one of the most common causes of treatable suffering in patients with advanced disease. Opioids are indispensable for pain management in palliative care and can usually be provided by the oral route, which is safe, effective, and of lowest cost in most cases. As patients near the end of life, however, the need for alternate routes of medication increases with up to 70% of patients requiring a nonoral route for opioid administration. In order to optimize patient care, it is imperative that clinicians understand existing available options of opioid administration and their respective advantages and disadvantages.

METHODS

We performed a literature review to describe the most commonly used and available routes that can substitute for oral opioid therapy and to provide a summary of factors affecting choice of opioid for use in palliative care in terms of benefits, indications, cautions, and general considerations.

RESULTS

Clinical circumstances will largely dictate appropriateness of the route selected. When the oral route is unavailable, subcutaneous, intravenous, and enteral routes are preferred in the palliative care population. The evidence supporting sublingual, buccal, rectal, and transdermal gel routes is mixed.

CONCLUSIONS

This review is not designed to be a critical appraisal of the quality of current evidence; rather, it is a summation of that evidence and of current clinical practices regarding alternate routes of opioid administration. In doing so, the overarching goal of this review is to support more informed clinical decision making.

Overview and appraisal of the current concept and technologies for improvement of sublingual drug delivery

Sublingual drug delivery is capable of achieving high bioavailability by avoiding first-pass liver extraction and enzymatic degradation in the gastrointestinal tract, as well as achieving rapid onset of effect. Thus, this route of administration can offer attractive therapeutic advantages for certain drugs as a convenient substitute for parenteral administration and has been applied successfully to a number of therapeutic conditions, especially urgent cardiovascular conditions and acute severe pain control. However, due to inherent limitations such as small sublingual mucosa area for absorption, primarily passive mechanism of transport, short residence time, and potential local irritation, a relatively small number of sublingual products have been successfully developed to date. In this Review, key concepts and technologies for potential improvement of sublingual drug delivery are reviewed. The optimal application of these concepts and technologies, together with clinical need for non-parenteral delivery, will hopefully broaden the development of sublingual drug delivery in the future.

Buprenorphine

In the crystal structure of a semi-synthetic opioid drug buprenorphine, C29H41NO4 {systematic name: (2S)-2-[(5R,6R,7R,14S)-9α-cyclo-propyl-methyl-3-hy-droxy-6-meth-oxy-4,5-ep-oxy-6,14-ethano-morphinan-7-yl]-3,3-di-methyl-butan-2-ol}, the cyclo-propyl-methyl group is disordered over two sites with an occupancy factor of 0.611 (3) for the major component. One of the hy-droxy groups is involved in intra-molecular O-H⋯O hydrogen bond. The other hy-droxy group acts as a proton donor in an inter-molecular O-H⋯O inter-action that connects mol-ecules into a zigzag chain along the b axis.

Levorphanol: revisiting an underutilized analgesic

Levorphanol (levo-3-hydroxy-N-methylmorphinan) is a step 3 opioid first developed in the 1940s as an alternative to morphine. Levorphanol belongs to the morphinan opioid series. Levorphanol has greater potency than morphine and is a potent N-methyl-d aspartate (NMDA) antagonist. Levorphanol interferes with the uptake of norepinephrine and serotonin, which makes it potentially useful for neuropathic pain. Glucuronidation changes Levorphanol to Levorphanol-3-glucuronide with excretion by the kidney. Levorphanol has a long half-life and may accumulate with repeated dosing. Levorphanol can be administered orally, intravenously, and subcutaneously. This article provides an update regarding the pharmacodynamics, pharmacology, and clinical efficacy of this often overlooked step 3 opioid.

Single-dose pharmacokinetics of fentanyl sublingual spray and oral transmucosal fentanyl citrate in healthy volunteers: a randomized crossover study

BACKGROUND

Fentanyl sublingual spray (FSS) is a novel fentanyl formulation recently developed for the treatment of breakthrough cancer pain, which is characterized by a fast onset and a relatively short duration.

OBJECTIVE

To compare rate of absorption and systemic bioavailability between FSS and oral transmucosal fentanyl citrate (OTFC) in healthy volunteers.

METHODS

This randomized 3-way crossover study involved 29 healthy volunteers (25 men and 4 women; mean age, 35 years) who received single doses of FSS (400 μg), OTFC (400 μg), and intravenous fentanyl citrate (100 μg) separated by washout periods of ≥7 days. Oral naltrexone was given to minimize potential adverse effects of fentanyl. Plasma fentanyl concentrations were measured for 36 hours after each dose for the calculation of pharmacokinetic parameters.

RESULTS

Mean Cmax values of fentanyl were higher with FSS versus OTFC (0.81 ng/mL vs 0.61 ng/mL) and were attained more quickly; the median Tmax was 1.5 hours with FSS and 2.0 hours with OTFC (P < 0.05). Furthermore, potentially effective fentanyl concentrations were achieved more quickly with FSS than with OTFC. Five and 10 minutes after administration, mean plasma concentrations were 19.0% and 53.7% of Cmax with FSS, respectively, compared with levels below the lower limit of assay quantification and 6.1%, respectively, with OTFC. Plasma concentrations of fentanyl at 10 minutes with FSS were equivalent to those with OTFC at 60 minutes. The Cmax and AUCs were approximately 33% to 36% greater with FSS than with OTFC, and the 90% CIs of the geometric mean ratios for each parameter fell outside the bioequivalence range of 80% to 125%. Systemic bioavailability was also greater with FSS than with OTFC (approximately 76% vs 51%). All 3 fentanyl treatments were well tolerated. All reported adverse events were mild and consistent with those previously reported in healthy volunteers receiving transmucosal fentanyl with naltrexone, and none occurred in >2 participants during any treatment period.

CONCLUSIONS

Absorption of fentanyl in this study was faster and bioavailability was greater with FSS than with OTFC. The pharmacokinetic profile of the sublingual spray closely matches the duration of onset to pain intensity in a breakthrough cancer pain episode. These findings suggest that FSS is appropriate for the treatment of breakthrough cancer pain. ClinicalTrials.gov identifier: NCT01780233.

Intranasal fentanyl in the palliative care of newborns and infants

CONTEXT

Perinatal palliative care is an area of increasing focus among clinicians supporting newborns and their families. Although not every newborn will survive the neonatal period, assuring their comfort and quality of life remains an imperative for their care providers. It can be challenging to administer medications such as opioids in a minimally invasive yet effective manner.

OBJECTIVES

To describe the experience using intranasal (IN) fentanyl in the management of distress in a case series of 11 dying neonates.

METHODS

A retrospective chart review was undertaken of 58 consecutive referrals of newborns and infants aged six months or younger between November 2006 and July 2010 to the Winnipeg Regional Health Authority Pediatric Palliative Care Service to determine how often IN fentanyl was used and review documented responses after the medication.

RESULTS

Of 58 referrals, IN fentanyl was used in 11 patients, in all cases for concerns regarding respiratory distress. Chart documentation indicated that fentanyl was tolerated well, with no circumstances of drug-related apnea and no occurrences of chest wall rigidity. In most cases, labored breathing and restlessness settled after medication administration. The average time from administration of the last dose of fentanyl until death was 61 minutes.

CONCLUSION

We found IN fentanyl, which can be administered in a variety of care settings, to be a minimally invasive means of palliating distress in dying newborns and infants. No adverse events related to its use were noted.