Likeability and abuse liability of commonly prescribed opioids

INTRODUCTION

Nonmedical use of prescription opioid analgesics is associated with epidemic levels of morbidity and mortality. There are several factors that affect the abuse liability of the various opioids, including likability or the pleasurable subjective effects. Due to rising public health concerns over escalating prescription opioid abuse, we sought to examine the literature about abuse liability with a specific focus on likability studies.

METHODS

A search of EMBASE and MEDLINE databases identified articles that described the comparative likeability and/or abuse potential of hydrocodone and oxycodone relative to each other and/or of either one to morphine. After an assessment of study quality using the Oxford/Jadad scale, relevant details such as demographics, study design, and outcome measures were compiled into an evidence table.

RESULTS

We identified nine studies that met inclusion criteria. All were double-blinded, randomized, placebo-controlled crossover studies and scored 5 out of 5 Jadad scale. There was no consistent clinically significant difference between abuse liability of morphine and hydrocodone. Oxycodone demonstrated high abuse liability on the basis of its high likability scores and a relative lack of negative subjective effects.

CONCLUSION

Oral oxycodone has an elevated abuse liability profile compared to oral morphine and hydrocodone.

The Novel Development of an Experimental Model of Dihydropyridine Calcium Channel Blocker Poisoning using Intravenous Amlodipine

BACKGROUND

Cardiovascular drug poisoning remains a leading cause of fatality. Within this class, calcium channel blockers (CCBs) account for the majority of deaths. CCBs are typically categorized as dihydropyridines (i.e. amlodipine or nifedipine) versus the non-dihydropyridine (i.e. verapamil and diltiazem) which are the most potent and once considered the CCB type responsible for all CCB-related deaths. Most recently, dihydropyridine deaths have increased. While there are established models of nondihydropyridine poisoning there currently are no established experimental models of dihydropyridine poisoning.

METHODS

Electrocardiogram electrodes and intravenous lines were placed in anesthetized Spraque-Dawley rats. Various doses of amlodipine were administrated as a constant infusion to mimic continued gastrointestinal absorption. Intravenous amlodipine dosing was determined by the Dixon "up-and-down" method. Animals were observed for a total of two hours and death or survival was recorded.

RESULTS

Various solvents were used such as tween and ethanol. Amlodipine was successfully dissolved in 20% DMSO. The maximum likelihood estimate for LD50 was 8.65 mg/kg (SE, +/- 2.67 mg/kg). CONCLUSIONS: A reliable experimental model of dihydropyridine poisoning using intravenous amlodipine is presented which will allow future studies concerning pathophysiology of shock from dihydropyridine poisoning and treatment.

Windmills and pill mills: can PDMPs tilt the prescription drug epidemic?

Prescription drug monitoring programs (PDMPs) are state-based registries of prescriptions for specific controlled substances. This overview will describe the history and funding of these databases, address those characteristics thought to be of greatest utility for PDMPs and review current literature regarding PDMP effectiveness and their potential limitations. Although more extensive research on PDMP outcomes is needed, these databases are an essential component in ongoing efforts to establish safe and compassionate prescription opioid stewardship.

Epidemiology of smear-negative pulmonary tuberculosis in the United States, 1993-2008

BACKGROUND

Smear-negative tuberculosis (TB) is difficult to diagnose and has been associated with poor treatment outcomes and excessive mortality, particularly in high human immunodeficiency virus (HIV) prevalent settings. However, few studies have used mycobacterial culture to rigorously confirm all smear-negative TB cases in a population-based cohort.

DESIGN

We included all culture-confirmed, pulmonary TB cases reported to the US National TB Surveillance System from 1993 to 2008. We analyzed smear-negative TB risk factors and survival, as compared to smear-positive TB. We calculated prevalence ratios (PRs) and adjusted for confounders (aPR).

RESULTS

From 1993 to 2008, 159,121 cases of culture-confirmed pulmonary TB were reported in the United States, of which 58,786 (37%) were sputum smear-negative. Smear-negative TB cases were more likely to be foreign-born (aPR 1.10, 95%CI 1.08-1.12), incarcerated (aPR 1.52, 95%CI 1.48-1.56) or HIV-infected (aPR 1.27, 95%CI 1.24-1.30). Hispanics and non-Hispanic Blacks were less likely to have smear-negative TB (respectively aPR 0.87, 95%CI 0.85-0.89 and aPR 0.90, 95%CI 0.89-0.92). Smear-negative TB cases had lower mortality (aRR 0.78, 95%CI 0.74-0.81), independent of HIV status.

CONCLUSION

Smear-negative TB represents a large proportion of TB cases in the United States, and occurs more often among persons in groups more likely to undergo TB screening. The lower mortality may indicate earlier TB detection, and underscores the need for continued vigilance in screening of high-risk persons.

Self-injurious behaviour in individuals with autism spectrum disorder and intellectual disability

BACKGROUND

Autism spectrum disorder (ASD) has been identified as a risk marker for self-injurious behaviour. In this study we aimed to describe the prevalence, topography and correlates of self-injury in individuals with ASD in contrast to individuals with Fragile X and Down syndromes and examine person characteristics associated with self-injury across and within these groups.

METHOD

Carers of individuals with ASD (n = 149; mean age = 9.98, SD = 4.86), Fragile X syndrome (n = 123; mean age = 15.32, SD = 8.74) and Down syndrome (n = 49; mean age = 15.84, SD = 12.59) completed questionnaires relating to the presence and topography of self-injury. Information was also gathered regarding demographic characteristics, affect, autistic behaviour, hyperactivity, impulsivity and repetitive behaviour.

RESULTS

Self-injurious behaviour was displayed by 50% of the ASD sample: a significantly higher prevalence than in the Down syndrome group (18.4%) but broadly similar to the prevalence in Fragile X syndrome (54.5%). Self-injury was associated with significantly higher levels of autistic behaviour within the Down and Fragile X syndrome groups. Within the ASD group, the presence of self-injury was associated with significantly higher levels of impulsivity and hyperactivity, negative affect and significantly lower levels of ability and speech.

CONCLUSIONS

Self-injurious behaviour is prevalent in individuals with ASD and the presence of ASD phenomenology increases the risk of self-injury in individuals with known genetic disorders but without a diagnosis of idiopathic autism. Person characteristics associated with self-injury in ASD indicate a role for impaired behavioural inhibition, low levels of ability and negative affect in the development of self-injurious behaviour.

Complications of oral exposure to fentanyl transdermal delivery system patches

PURPOSE

Fentanyl is a synthetic opioid available therapeutically as an intravenous, transbucal, or transdermal preparation. It is also used as a drug of abuse through a variety of different methods, including the oral abuse of transdermal fentanyl patches. This is a series of patients with oral fentanyl patch exposure reported to our center and represents the first series of oral fentanyl patch exposures collected outside of the postmortem setting.

METHODS

In this series, we examined the New York Poison Control Center database for all cases of oral abuse of fentanyl reported between January 2000 and April 2008.

RESULTS

Twenty cases were reported, nine were asymptomatic or had symptoms of opioid withdrawal; 11 had symptoms of opioid intoxication. Eight patients were administered naloxone and all showed improvement in clinical status. Only one case resulted in a confirmed fatality-this patient had an orally adherent patch discovered at intubation.

CONCLUSIONS

Oral exposure may result in life-threatening toxicity. Patients should be closely assessed and monitored for the opioid toxidrome, and if symptomatic, should be managed with opioid antagonists and ventilatory support.

2007 survey of medical toxicology practice

To date, there appear to be no studies investigating the practice settings of all Medical Toxicology (MT) diplomates. The MT Assessment of Practice Performance Taskforce queried all MT diplomates about their current practice settings relative to the number of patients seen, the most common diagnoses, and the percent of time spent in their roles as medical toxicologists (MTs) and in their primary specialty. One hundred twenty-seven surveys were completed (44% response rate). Seventy-nine percent of respondents were affiliated with poison centers. Eighty-eight percent of participants were clinically active and reported seeing or consulting on behalf of at least ten patients over a 2-year period. Acetaminophen toxicity was the most common diagnosis encountered by respondents. Other common diagnoses included antidepressant toxicity, antipsychotic toxicity, mental status alteration, metal/environmental toxicity, envenomation, and pesticide toxicity. While respondents were likely to spend more time in direct patient care in their primary specialty, compared to consulting on behalf of patients, they were more likely to consult on behalf of patients in their role as MTs. Respondents spent more time in research, education, and population health in their role as an MT than in their primary specialty. Administrative activities were more commonly reported in association with the respondents' primary specialty than in their role as MTs. Most MTs encounter certain diagnoses with significant frequency and see a substantial number of patients within these categories. The majority spends more time on direct patient care in their primary specialty but is actively engaged in MT education, research, population health, and administration. A longitudinal assessment of MT practice patterns could inform MT curricular development and practice performance evaluation.

Use of stem cells in the biological repair of articular cartilage

IMPORTANCE OF THE FIELD

Articular cartilage is avascular, aneural, and renowned for its poor capacity to repair after damage. For decades scientists and clinicians have deliberated over the potential to repair or regenerate articular cartilage and to date many techniques have been used in an attempt to create the best possible repair tissue.

AREAS COVERED IN THIS REVIEW

This review article summarises surgical interventions that have been developed since the late 1940's; covering conservative strategies, invasive techniques and touching upon latest advancements involving stem cells and tissue engineering.

WHAT WILL THE READER GAIN

The reader will gain a sound understanding into the history and background of strategies that have developed in attempts to reverse clinical symptoms of damaged or diseased articular cartilage. The article provides an insight into the plethora of potential repair mechanisms, and reviews future developments involving stem cells and biomaterials.

TAKE HOME MESSAGE

Although work is still in its infancy, the use of stem cells in the biological repair of articular cartilage provides a promising outlook onto future developments; advancing from strategies and techniques that are already in use.

2007 survey of medical toxicology practice improvement activities

To date, there appear to be no studies that assess Medical Toxicologists' (MTs) practice improvement (PI) activities in their Medical Toxicology practice settings. The MT Assessment of Practice Performance (APP) Taskforce queried all MT diplomates about (1) activities currently available in their practice settings that potentially would meet the requirements of APP, (2) potential APP activities that best fit with current MT practice, and (3) the relationship between MT practice patterns and APP requirements. One hundred twenty-seven surveys were completed. Participation in MT practice improvement activities is not universal, with approximately a third of the survey participants reporting that they are not involved in any practice improvement activity. Few respondents reported that they collected performance improvement-related data. Most who did so participated in CME, case, or chart reviews. Peer reviews, self-improvement plans based on chart reviews, and population research were considered the most valid measures of MT practice improvement. Communication skills were considered important topics for patient surveys. Suggested outcomes for peer assessment included accuracy of information provided, understanding medical staff concerns, timeliness of feedback, and helpfulness. Most respondents rated all of the APP options as being somewhat very intrusive. Access to those with sufficient knowledge of the diplomate's practice improvement program to verify APP could pose a challenge to a successful completion of APP requirements. Optimal settings for the APP program administration are hospitals and poison centers. While barriers to MT APP activities exist, studying current MT diplomates' opinions and practices could inform the future development and administration of such programs.

Transdermal fentanyl: pharmacology and toxicology

OBJECTIVE

To evaluate the underlying pharmacology, safety, and misuse/abuse of transdermal fentanyl, one of the cornerstone pharmacotherapies for patients with chronic pain.

METHODS

Literature was identified through searches of Medline (PubMed) and several textbooks in the areas of pharmacology, toxicology, and pain management. A bibliographical review of articles identified by these searches was also performed. Search terms included combinations of the following: fentanyl, transdermal, patch, pharmacology, kinetics, toxicity, and poisoning. All pertinent clinical trials, retrospective studies, and case reports relevant to fentanyl pharmacology and transdermal fentanyl administered by any route and published in English were identified. Each was reviewed for data regarding the clinical pharmacology, abuse, misuse, and safety of transdermal fentanyl. Data from these studies and information from review articles and pharmaceutical prescribing information were included in this review.

RESULTS

Fentanyl is a high-potency opioid that has many uses in the treatment of both acute and chronic pain. Intentional or unintentional misuse, as well as abuse, may lead to significant clinical consequences, including death. Both the US Food and Drug Administration (FDA) and Health Canada have warned of potential pitfalls associated with transdermal fentanyl, although these have not been completely effective in preventing life-threatening adverse events and fatalities related to its inappropriate use.

CONCLUSIONS

Clinically consequential adverse effects may occur unexpectedly with normal use of transdermal fentanyl, or if misused or abused. Misuse and therapeutic error may be largely preventable through better education at all levels for both the prescriber and patient. The prevention of intentional misuse or abuse may require regulatory intervention.

Factors associated with positive tuberculin skin test results among HIV-infected persons in Orel Oblast, Russia

BACKGROUND

The treatment of persons living with human immunodeficiency virus/acquired immune-deficiency syndrome (PLWHAs) for latent tuberculosis infection (LTBI) reduces tuberculosis (TB) morbidity. Despite a high TB burden and an expanding human immunodeficiency virus epidemic, Russia had limited data on the utility of the tuberculin skin test (TST) for LTBI diagnosis in PLWHAs.

OBJECTIVE

To determine the prevalence and predictors of positive TSTs in PLWHAs in Orel Oblast.

METHODS

A total of 150 consenting PLWHAs being followed up at the AIDS Center were administered a TST and a questionnaire for risk factors for LTBI. A positive TST result was defined as >or=5 mm induration.

RESULTS

Of the 150 subjects, 67% were male and 74% were aged <30 years. Of the PLWHAs tested, 26% had a positive TST result, while among PLWHAs with CD4(+) >500 cells/ml, 36% were TST-positive. TST positivity varied inversely with CD4(+) cell count. Among PLWHAs with a history of injection drug use, the primary risk factor for HIV, 29 (31.9%) were positive.

CONCLUSIONS

A high proportion of tested PLWHAs had a positive TST and could benefit from preventive therapy (PT) to reduce the risk of TB. A TB control programme in Russia should therefore include TST screening among PLWHAs and PT, besides active TB case finding and treatment.