Matching study design to prescribing intention: The prevalent new-user design for studying abuse-deterrent formulations of opioids.

PURPOSE: In drug studies, research designs requiring no prior exposure to certain drug classes may restrict important populations. Since abuse-deterrent formulations (ADF) of opioids are routinely prescribed after other opioids, choice of study design, identification of appropriate comparators, and addressing confounding by "indication" are important considerations in ADF post-marketing studies. METHODS: In a retrospective cohort study using claims data (2006-2018) from a North Carolina private insurer [NC claims] and Merative MarketScan [MarketScan], we identified patients (18-64 years old) initiating ADF or non-ADF extended-release/long-acting (ER/LA) opioids. We compared patient characteristics and described opioid treatment history between treatment groups, classifying patients as traditional (no opioid claims during prior six-month washout period) or prevalent new users. RESULTS: We identified 8415 (NC claims) and 147 978 (MarketScan) ADF, and 10 114 (NC claims) and 232 028 (MarketScan) non-ADF ER/LA opioid initiators. Most had prior opioid exposure (ranging 64%-74%), and key clinical differences included higher prevalence of recent acute or chronic pain and surgery among patients initiating ADFs compared to non-ADF ER/LA initiators. Concurrent immediate-release opioid prescriptions at initiation were more common in prevalent new users than traditional new users. CONCLUSIONS: Careful consideration of the study design, comparator choice, and confounding by "indication" is crucial when examining ADF opioid use-related outcomes.

Assessing Abuse-Deterrent formulations utilizing Ion-Exchange resin complexation processed via Twin-Screw granulation for improved safety and effectiveness.

Opioid misuse is a public health crisis in the United States. In response, the FDA has approved drug products with abuse-deterrent features to reduce the risk of prescription opioid abuse. Abuse-deterrent formulations (ADFs) typically employ physical or chemical barriers or incorporate agonist-antagonist combinations as mechanisms to deter misuse. This study aims to assess the impact of abuse-deterrent properties, specifically ion-exchange resin complexation as a chemical barrier, on a model drug, promethazine hydrochloride (PMZ) tablets. Various formulations were developed through twin-screw wet granulation (TSWG) followed by twin-screw melt granulation (TSMG). In the TSWG process, the drug interacts with the resin through an exchange reaction, forming a drug-resin complex. Additionally, the study explored factors influencing the complex formation between the drug and resin, using the drug loading status as an indicator. DSC and ATR studies were carried out to confirm the formation of the drug-resin complex. Subsequently, hot melt granulation was employed to create a matrix tablet incorporating Kollidon® SR and Kollicoat® MAE 100P, thereby enabling sustained release properties. The drug-resin complex embedded in the matrix effectively deters abuse through methods like smoking, snorting, or parenteral injection, unless the drug can be extracted. In order to assess this, solvent extraction studies were conducted using an FDA-recommended solvents, determining the potential for abuse. Further investigations involved dissolution tests in change-over media, confirming the extended-release properties of the formulation. Results from dissolution studies comparing the ground and intact tablets provided positive evidence of the formulation's effectiveness in deterring abuse. Finally, alcohol-induced dose-dumping studies were conducted in compliance with FDA guidelines, concluding that the formulation successfully mitigates dose dumping in the presence of alcohol.

Asymmetrical Flow Field Flow Fractionation for Molar Mass Characterization of Polyethylene Oxide in Abuse-Deterrent Formulations.

High molar mass polyethylene oxide (HM-PEO) is commonly used to enhance the mechanical strength of solid oral opioid drug products to deter abuse. Because the properties of PEO depend on molar mass distribution, accurately determining the molar mass distribution is a necessary part of understanding PEO's role in abuse-deterrent formulations (ADF). In this study, an asymmetrical flow field-flow fractionation (AF4) analytical procedure was developed to characterize PEO polymers with nominal molar masses of 1, 4 or 7 MDa as well as those from in-house prepared placebo ADF. The placebo ADF were manufactured using direct compress or hot-melt-extrusion methods, and subjected to physical manipulation, such as heating and grinding before measurement by AF4 were performed. The molar mass distribution characterized by AF4 revealed that PEO was sensitive to thermal stress, exhibiting decreased molar mass with increased heat exposure. The optimized AF4 method was deemed suitable for characterizing HM-PEO, offering adequate dynamic separation range for PEO with molar mass from 100 kDa to approximately 10 MDa.

A Cross-Sectional Study of Tampering in Xtampza ER, an Abuse-Deterrent Formulation of an Extended-Release Opioid, in a Treatment Center Population.

BACKGROUND AND OBJECTIVE: While the current landscape of opioid use disorder (OUD) is complicated by the increase in use of non-prescription opioids, prescription opioids continue to be frequently used in non-medical ways. In response to this abuse, pharmaceutical companies have developed abuse deterrent formulations (ADFs) for extended-release (ER) opioids. To test the effectiveness of Xtampza ER ADF (oxycodone myristate) at reducing tampering, its rate of tampering in a treatment-center population was compared to immediate release (IR) single entity (SE) oxycodone, other ER oxycodone opioids, and ER oxymorphone. METHODS: Data were collected between the third quarter of 2018 and the third quarter of 2021 from individuals entering nationally distributed opioid treatment programs. To determine odds of tampering with Xtampza ER compared to each comparator, a logistic model was fit with a random intercept allowing for multiple drugs in each subject. Within-subject correlation was assumed to have a compound symmetric relationship. RESULTS: Overlap among the categories of drug tampering was high. Logistic regression analyses found that oxycodone myristate had lower odds of tampering when compared to both IR SE oxycodone (OR = 0.23 [95% CI 0.11, 0.50], p = 0.0002) and ER oxymorphone (OR = 0.30 [95% CI 0.14, 0.67], p = 0.0038). Oxycodone myristate was not significantly different from other ER oxycodone opioids (OR = 0.5 [95% CI 0.24, 1.03], p = 0.0612). These findings did not change when the estimates were adjusted for age and sex. CONCLUSIONS: Drugs employing ADF technology may reduce the likelihood of tampering when compared to non-ADF formulations in a treatment-center population, which represents an opportunity for intervention in OUD among those still requiring pain management.

Stability of Abuse-deterrent properties of PEO-based Abuse-deterrent formulation.

Abuse of opioid drug products is a national health crisis in the US. To deter abuse, a number of drug products with abuse-deterrent (AD) properties have been approved by the US Food and Drug Administration (FDA). For abuse deterrence, it is critical to maintain the AD properties during the product shelf life. However, no information on the stability of AD properties during product shelf life is publicly available. In this study, stability of AD properties of surrogate AD formulation (ADF) of opioid active pharmaceutical ingredients (APIs) were studied. Surrogate extended release (ER) AD tablets were prepared by direct compression using Diltiazem HCl (model drug), polyethylene oxide (PEO WSR 301) polymer and magnesium stearate followed by curing at 70 °C for 30 mins. The stability studies were conducted at 25 °C/60 % RH and 40 °C/75 % RH storage conditions for 12 months (M) and 6 months (M), respectively. In vitro characterization and evaluation of AD properties of tablets were performed. As anticipated, the curing process increased the crushing strength of the tablets. However, the tablets could still be manipulated and compromised leading to an enhancement in the amount of drug extracted in solvents (e.g., water, alcohol), regardless of extraction temperature as well as tablet storage condition and time. Furthermore, the granule particle size as well as viscosity in water of manipulated samples were found to be lower for tablets stored at 25 °C/60 % RH or 40 °C/75 % RH for 12 M or 3 M/6M, respectively. The changes in AD properties eased the syringeability of hydrated samples and ultimately led to the withdrawal of higher amounts of drug into the syringe, thereby, impacting the abuse deterrence potential of the formulation by an IV route. These data demonstrated that the stability of AD properties (i.e., granule particle size, viscosity and syringeability-injectability) of PEO-based tablets was dependent on the storage condition. In conclusion, the design of AD formulation and setting of product quality profile should take into consideration the stability of AD properties during the product shelf life.

An evaluation method for developing abuse-deterrent opioid formulations with agonist and antagonist combinations using conditioned place preference.

Although opioids are useful narcotic analgesics in clinical settings, their misuse and addiction in the United States of America and other countries are rapidly increasing. Therefore, the development of abuse-deterrent formulations is an urgent issue. We herein investigated how to select the ratio of an opioid and the opioid receptor antagonist, naloxone in abuse-deterrent formulations for mice. The conditioned place preference (CPP) test was used to evaluate the rewarding effects of abused drugs. The opioids morphine (30 µmol/kg), oxycodone (3 µmol/kg), fentanyl (0.4 µmol/kg), and buprenorphine (0.5 µmol/kg) significantly induced place preference in mice. We also examined the optimal ratio of naloxone and opioids to inhibit the rewarding effects of the latter. Naloxone (3-5 µmol/kg) effectively inhibited place preference induced by the opioids tested. We calculated theoretical drug doses that exerted the same pharmacodynamic effects based on two parameters: µ-opioid receptor binding affinity and blood-brain barrier (BBB) permeability. Theoretical doses were very close to the drug doses at which mice showed place preference. Therefore, the CPP test is useful as a behavioral method for evaluating abuse-deterrent formulations of opioids mixed with an antagonist. The ratio of naloxone with opioids, at which mice did not show place preference, may be an effective index for developing abuse-deterrent formulations. Ratios may be calculated for other opioids based on µ-opioid receptor binding affinity and BBB permeability.

PLA-PCL microsphere formulation to deter abuse of prescription opioids by smoking.

Opioids are commonly prescribed across the United States (US) for pain relief, despite their highly addictive nature that often leads to abuse and overdose deaths. Abuse deterrent formulations (ADFs) for prescription opioids make the non-therapeutic use of these drugs more difficult and less satisfying. Although approximately one-third of surveyed abusers in the US reported smoking opioids, to our knowledge, no commercialized ADF effectively prevents opioid smoking. Here, we report a novel approach to deter smoking of a model prescription opioid drug, thebaine (THB), by using polymer blend microspheres (MS) comprising polylactic acid (PLA) and polycaprolactone (PCL). We utilized high-performance liquid chromatography (HPLC) and thermogravimetric analysis (TGA) to test the ability of PLA-PCL MS to limit the escape of vaporized THB. Additionally, we compared the abuse-deterrent potential of PLA-PCL MS to that of activated carbon (AC) and mesoporous silica (MPS), two materials with excellent drug-adsorbing properties. Our MS formulation was effective in reducing the amount of both active drug and thermal degradation products in the vapor generated upon heating of THB. These results support that PLA-PCL microspheres can be co-formulated in a tablet with common prescription opioids to deter their abuse via the smoking route.

Aversion liquid-filled drug releasing capsule (3D-RECAL): A novel technology for the development of immediate release abuse deterrent formulations using a fused deposition modelling (FDM) 3D printer.

COVID19 has caused a significant socioeconomic burden worldwide. Opioid crisis was further intensified with the increasing number of opioid overdose/misuse related deaths in last two years. Abusers have adopted newer/efficient methods for manipulating and abusing commercial opioid formulations. Food and Drug Administration (FDA) has been strategizing tirelessly to prevent misuse/abuse of prescription opioids. One of the strategies is to develop an abuse deterrent formulation (ADF). The current study aims to develop a novel 3D printed drug-releasing capsule shell filled with an aversion liquid (3D-RECAL). Primarily, metformin hydrochloride (MT, model drug) loaded printable filaments of polyvinyl alcohol was prepared using hot melt extrusion. Following extrusion, a 3D printed capsule shell was designed and fabricated using a single nozzle fuse deposition modelling 3D printer. An aversion liquid to be filled in 3D-RECAL capsules was prepared by combining sudan black and sodium polyacrylamide starch in oil base. Mechanical analysis of extruded filaments suggested that the filaments with 20%w/w MT had a higher mechanical strength compared to other drug loadings. Instantaneous gelling and large black non-snortable particles were formed during solvent extraction and physical manipulation studies, respectively. Due to the drug being embedded in the capsule shell, MT release was immediately started with >85% of MT release within 45 mins in 0.1 N HCl. Due to the everlasting need for the newer efficient ADF technologies, 3D-RECAL can be a step in the right direction towards saving lives, providing safe and effective measures to deterring abusers.

Abuse of immediate-release opioids and current approaches to reduce misuse, abuse and diversion.

Deaths from opioid overdoses have increased dramatically over the past few years. Given that immediate-release (IR) opioids account for most of the U.S. market share, and that abusers generally prefer IR opioids over extended-release (ER) opioids, it is not surprising that rates of abuse are higher for IR than ER opioids. IR opioids are widely prescribed, often without consideration for risks of abuse, misuse, and diversion. Prescription opioid abuse and misuse often begins through oral administration and progresses into non-oral routes (e.g. snorting, injecting) as abusers gain more experience; non-oral routes carry heightened safety concerns. Current approaches used for reducing opioid abuse include U.S. Food and Drug Administration regulations, state legislation, insurance company policies, the use of multimodal analgesic therapy, patient risk assessment and monitoring, limiting access to opioids by reducing IR opioid prescription quantity and length, prescription drug monitoring programs, patient education on proper disposal of unused medication and risks of diversion, as well as abuse-deterrent formulations. Albeit, most abuse-deterrent formulations have focused on ways to prevent the circumvention of ER characteristics rather than placing obstacles to abuse of IR opioid formulations. Reducing opioid abuse requires the combined efforts of multiple stakeholders, including prescribing clinicians, patients, pharmacists, nurses, insurance companies, government agencies, and pharmaceutical companies.

Abuse-Deterrent Formulations in Constraining the Abuse Potential of Prescription Medicines: A Myth or Truth.

BACKGROUND: Diverse pain killers used for the management of varied categories of pain are being misused in order to have extreme pleasant effects by a large number of populations. To overcome the misuse of prescription drugs, regulatory bodies have given stress on the development of abuse resistance. METHODS: We studied numerous literatures: (1) Research and review papers including the guidelines for pain management, abuse, and abuse deterrence; (2) Description and categorization of pain along with the management approaches; (3) Advantages and disadvantages of the abuse-deterrent formulations. RESULTS: Abuse-deterrent formulations are the contemporary remedial treatment for pain with reduced prospects of being abused. But these comprise huge expense in contrast to the generic drugs as well as the non-deterrent branded equivalents. CONCLUSION: Many challenges are faced throughout the development of abuse-deterrent formulations. These formulations displayed a substantial drop in abuse incidences but it may lead to other modes of abuse, which may prove more harmful for the users.

Emerging Trends in Abuse-Deterrent Formulations: Technological Insights and Regulatory Considerations.

BACKGROUND: Opioid medications are an integral part of the management of acute and chronic severe pain. However, non-medical practice of these prescription drug products is emerging as a serious public health problem. To control this opioid epidemic, USFDA is encouraging pharmaceutical companies to develop Abuse Deterrent Formulations (ADFs). ADF's are much more difficult to manipulate and abuse when compared to their conventional formulations. This feature of ADFs is due to their ability to incumber extraction of active ingredients, to prevent administration through alternative routes, making abuse of altered product less rewarding. OBJECTIVE: The main objective of this review is to abridge different ADFs and various laboratory- based in vitro manipulation and extraction studies, demonstrating that these approved ADFs have the capabilities to deter abuse. METHODS: The method includes the collection of data from different search engines like PubMed, FDA guidance documents, ScienceDirect, Google Patents to get coverage of literature in order to get appropriate information regarding ADFs. RESULTS: Various in vitro studies demonstrate that ADFs are effective in minimizing opioid drug abuse, including opioid overdose. However, real impact of these ADFs on reducing the drug abuse can be concluded only after receiving the post marketing data. CONCLUSION: ADFs are embracing fundamentally different paradigms in the management of severe pain. We believe that the development of abuse deterrent technologies would shift the architype, deterring multipill abuse and can prove as a breakthrough strategy in controlling this opioid epidemic menace.

Preferential Oxycodone Loss of Physically Manipulated Abuse Deterrent Oxycodone HCl Extended Release Tablets Prepared for Nasal Insufflation Studies.

A method to reproducibly mill abuse deterrent oxycodone hydrochloride (HCl) extended release (ER) tablets was developed for a nasal insufflation pharmacokinetic (PK) study. Several comminution methods were explored before determining that a conical mill resulted in controlled milling of tablets to a size range equal to or below 1000 µm. However, milling resulted in significant loss of oxycodone from abuse deterrent oxycodone HCl ER tablets compared to minimal oxycodone loss from oxycodone HCl immediate release (IR) tablets. Characterization of milled tablet powder showed that loss of oxycodone was not attributed to analytical procedures or oxycodone phase change during high intensity milling processes. The content uniformity of oxycodone in the milled tablet powder varied when ER and IR tablets were milled to a particle size distribution equal to or below 500 µm but did not vary when particles were sized above 500 µm to equal to or below 1000 µm. In addition, the initial excipient weight to drug substance weight ratio impacted the amount of oxycodone lost from the respective formulation. However, dissolution demonstrated that when oxycodone HCl ER tablets are milled, differences in excipient weight to drug substance weight ratio and particle size distribution of milled tablets did not result in significantly different release of oxycodone.

Particle size affects pharmacokinetics of milled oxycodone hydrochloride tablet products following nasal insufflation in nondependent, recreational opioid users.

This study assessed the impact of product particle sizes (fine: 106-500 µm; coarse: 500-1000 µm) on oxycodone pharmacokinetics (PK) following nasal insufflation of milled oxycodone extended-release (ER) abuse-deterrent (AD) tablets using immediate-release (IR) non-AD product as reference. Additionally, this study assessed the effects of different excipient to drug ratio (EDR) by comparing two products with fine particle size but different EDRs, again using IR non-AD as the control. Thirty milligrams of oxycodone were administered in each treatment. Coarsely milled 30 mg ER tablets demonstrated significantly lower maximum plasma concentration (Cmax ) and partial areas under the concentration-time curve (AUCs) than those of the finely milled IR tablets. Finely milled ER tablets demonstrated similar Cmax and partial AUCs but higher total systemic exposures than those of finely milled IR tablets. Finely milled 80 mg ER tablets were bioequivalent to IR tablet on all parameters. The finely milled 30 mg ER tablet was not bioequivalent to the coarsely milled 30 mg ER tablet and had higher values for all parameters. The finely milled 30 mg ER tablets (EDR 6.9) showed no PK differences with finely milled 80 mg ER tablets (EDR 4.9). No serious adverse events were reported. The study demonstrated a significant effect of particle sizes (106-1000 µm) on PK of milled and insufflated oxycodone ER AD tablets. EDR difference did not have any significant effects on the PK of finely milled oxycodone ER AD tablets. Particle size distribution should be considered when nasal AD properties of opioid drug products are investigated during drug development.

Evaluation of tableting performance of Poly (ethylene oxide) in abuse-deterrent formulations using compaction simulation studies.

Poly (ethylene oxide) (PEO) has been widely used in abuse-deterrent formulations (ADFs) to increase tablet hardness. Previous studies have shown that formulation variables such as processing conditions and particle size of PEO can affect ADF performance in drug extraction efficiency. This work aims to understand the effect of PEO grades and sources on the compaction characteristics of model ADFs. PEOs from Dow Chemical and Sumitomo Chemical with different molecular weights were examined using a Styl'One compaction simulator at slow, medium, and fast tableting speeds. Particle-size distribution, thermal behavior, tabletability, compressibility using the Heckel model, compactibility, and elastic recovery were determined and compared between the neat PEOs and model ADFs. Multivariate linear regression was performed to understand the effect of compression conditions and PEO grades and sources. Our results show that neat PEOs with high molecular weight exhibit high tabletability. The source of neat PEOs contributes to the difference in tabletability, out-die compressibility, compactibility, and elastic recovery. However, the influence of the PEO source on tabletability and compactibility decreases after adding the model drug. In our model ADFs, tablets using PEOs with high molecular weight have high crushing strength, and tablets using PEOs from Dow Chemical display low elastic recovery.

Use of Partial Area Under the Curve in Bioavailability or Bioequivalence Assessments: A Regulatory Perspective.

Peak drug concentration (Cmax ) and total exposure, such as area under the concentration-time curve (AUC) from time zero to infinity may be insufficient for assessing relative bioavailability (BA) or bioequivalence (BE) among two products in cases where rapid onset of action or controlled duration of effect is needed to ensure similar drug efficacy. Regulatory agencies have recommended the use of partial AUC (pAUC) as an additional exposure measure for relative BA or BE assessments. The pAUC metric describes pharmacokinetic profiles with the focus on quantification of exposures over specific time intervals to support the determination of relative BA or BE for these drug products in relation to respective reference products. The principles and rationales for using pAUCs are included in the US Food and Drug Administration (FDA)'s general BA or BE guidances. Specific pAUC recommendations are also reflected in product-specific guidances for generic drug development published by the FDA. Rationales for the use of pAUCs in relative BA or BE assessments are based on drug-specific and product-specific considerations. This white paper introduces the general framework, including rationales for pAUC recommendations, and provides an overview of the current status, challenges, and the FDA considerations on the use of pAUC for relative BA or BE assessments in the United States.

Variation in Abuse-Deterrent Formulation Opioid Prescribing in California, Florida, and Kentucky in 2018.

PURPOSE: Abuse-deterrent formulation (ADF) opioid analgesics have been developed as a means to address prescription opioid abuse. ADF opioid use in clinical practice is not well described in the literature. This study characterizes ADF opioid prescribing patterns in 3 diverse states. METHODS: This study used data from prescription drug monitoring programs (PDMPs) in California, Florida, and Kentucky. The sample includes all ADF opioid prescriptions for patients ≥18 years old during the study period (CY 2018). Standardized prescribing rates were calculated by age, sex, and county rurality. The ADF opioid prescribing rate was calculated per 1,000 adult recipients of opioid analgesics. FINDINGS: The rate of ADF prescribing per 1,000 adult recipients of opioid analgesics was nearly twice as high in Florida (14.57; 95% CI: 14.44-14.69) than in California (8.30; 95% CI: 8.22-8.37) or Kentucky (8.20; 95% CI: 8.01-8.39). ADF prescribing rates were highest among adults ages 55-74 years and among males. ADF opioid prescribing in rural counties represented a greater proportion of total patients using opioid analgesics than in metro counties in California (RR 1.40; CI: 1.28-1.53). Opposite and less pronounced variation was observed in Kentucky (RR 0.93; 95% CI: 0.88-0.98), and a significant difference was not observed in Florida (RR 0.68; 95% CI: 0.38-1.19). CONCLUSIONS: There were significant differences in the ADF prescribing rates among the 3 states and in rural versus metro counties within 2 states. ADF opioid prescribing by age and sex showed similar trends within states. Further research is needed to elucidate contextual factors which may lead to prescribing variation.

Application of Hot Melt Extrusion Technology in the Development of Abuse-Deterrent Formulations: An Overview.

The misuse, abuse, and illicit use of prescription opioid analgesics is a global public health concern. However, there are many viable therapeutic options for the treatment of patients with chronic pain. Both intact and manipulated opioid drug products are abused by various routes such as oral, nasal, and injection, which may lead to overdose, drug addiction, and even death. To combat the abuse of these medications, regulatory agencies and pharmaceutical companies are switching their interest towards developing Abuse Deterrent Formulations (ADFs), with the intent to deter the abuse of opioid products to a maximum extent. There are several manufacturing strategies implemented in an attempt to develop ADFs. An example includes matrix tablets of high molecular weight polymers such as polyethylene oxide. The scalable and continuous manufacturing techniques, such as Hot-Melt Extrusion (HME), is increasingly accepted by pharmaceutical companies to advance the development and manufacturing of ADFs. The application of the HME technique in the development of ADFs may overcome the challenges of opioid analgesic formulation development and provide improved protection against misuse and abuse, while also ensuring access to safe and effective use in patients with chronic pain. This review deals with a brief overview of strategies, with emphasis on HME to deter opioid abuse, in vitro characterization methods, commonly used excipients in the development of ADFs, and regulatory standards to meet the requirements of ADFs.

Reviewing the role of emerging therapies in the ADHD armamentarium.

Introduction: Attention-deficit/hyperactivity disorder (ADHD) is a common neurobehavioral disorder that can be treated with both pharmacologic and nonpharmacologic modalities. Effective drug treatments for ADHD have been available for more than six decades. However, initial treatments had limitations in duration of effect, need for multiple daily doses, requirement for patients to swallow intact tablets, adverse effects and risk for abuse and diversion. During the past 20 years, more than two dozen stimulant and nonstimulant drugs have been developed. Nonetheless, there remain unmet needs in the treatment of ADHD.Areas covered: New stimulant and nonstimulant formulations in development are reviewed with emphasis on drugs in phase II and III trials. Efficacy, mechanism of action and adverse effect data are described where available. Abuse liability studies are described for abuse-deterrent formulations in development.Expert opinion: The review found a robust pipeline of stimulants and nonstimulants. Medications in development are formulated to optimize onset and duration of effect, alter the time of administration, obviate the need to swallow whole capsules or tablets and to deter abuse. While each of these formulations may fill a unique niche, these incremental improvements based on new drug delivery technologies may lead to very significant clinical effects.

An update on the clinical pharmacology of methylphenidate: therapeutic efficacy, abuse potential and future considerations.

INTRODUCTION: Methylphenidate remains a first-line medication for treating ADHD in children and adults. However, its behavioral pharmacological similarities to methamphetamine and cocaine have historically created concern for its potential as a drug of abuse. In September 2019, the FDA published a docket requesting comments for the development of abuse deterrent formulations for CNS stimulants, emphasizing the abuse of methylphenidate as a public health concern. AREAS COVERED: We conducted a narrative review of research on the clinical pharmacology, therapeutic efficacy, and abuse potential of methylphenidate. EXPERT OPINION: Several studies indicate that methylphenidate has at least some abuse potential. Methylphenidate, amphetamine, methamphetamine, and cocaine overlap in their subjective, reinforcing, and discriminative stimulus effects. Regardless, methylphenidate remains an efficacious treatment for ADHD in children and adults when properly adhered to, especially when paired with non-pharmacological treatments. The development of abuse deterrent formulations of methylphenidate is warranted.

Opioid analgesia: recent developments.

PURPOSE OF REVIEW: Opioids are potent drugs for the treatment of severe pain, but they are burdened by detrimental side-effects, such as respiratory depression, addiction, sedation and constipation. Their clinical application is undisputed in acute (e.g. perioperative) and cancer pain, but their use in chronic nonmalignant pain has met increasing scrutiny and has contributed to the opioid crisis. Thus, novel analgesics with reduced side-effects are badly needed. RECENT FINDINGS: Current research topics include enkephalinase inhibitors, allosteric and multivalent ligands, biased opioid receptor signaling and selective activation of peripheral opioid receptors in injured tissues. SUMMARY: Opioids still appear to be most promising among current approaches in the development of analgesics. Basic knowledge about pathophysiology of clinical pain and novel insights in pharmacology suggest that the most interesting perspectives are augmenting endogenous opioid actions and selectively targeting peripheral opioid receptors. The latter approach is additionally supported by evidence from clinical studies. Some biased, multivalent and peripherally selective agonists have advanced to phase III trials, but novel drugs have not become available for clinical application. Future strategies in analgesic drug development might include public-private partnerships and nonprofit pharmaceutical companies, as exemplified by the AIDS crisis and proposals to combat antibiotic resistance.