Comparison of Quetiapine Abuse and Misuse Reports to the FDA Adverse Event Reporting System With Other Second-Generation Antipsychotics

Prescription patterns of quetiapine for multiple drug abuse, depression, and psychosis: A retrospective study

Background

Quetiapine is an atypical antipsychotic prescribed for schizophrenia, bipolar disorder, multiple drug abuse (MDA), generalized anxiety disorder, severe depression, dementia, and mood disorders. Prescription of quetiapine varies according to use, with side effects increasingly reported with higher doses. Many previous case reports highlighted the misuse of the drug. Here we studied the prescribing patterns of quetiapine in multiple drug abuse (MDA), depression, and psychosis patients in the Madinah region in Saudi Arabia.

Methods

This is a retrospective single-center study carried out in the main referral hospital for mental health in Madinah, Saudi Arabia for the period December 2020 till December 2021.

Results

A total of 158 patients were included in this study. The mean age of the patients was 30.5 ± 10.1 years. Male presented for 89.9 % of the patients. In terms of quetiapine indications, 46.2 % of patients used it for MDA, 29.7 % for psychosis, and 24.1 for depression. For all patients, quetiapine was used with a mean daily dose of 285.2 ± 222 mg and for a mean duration of 13.9 ± 15.4 weeks. Quetiapine was prescribed with a mean of 2.1 ± 2.2 prescriptions. Comparison between different indications shows that quetiapine was more frequently prescribed for MDA (p < 0.001). The MDA patients were significantly younger than in other groups (p = 0.001). All patients who received quetiapine for MDA were males. However, MDA patients received a smaller dose of quetiapine than other indications (p < 0.001). There were no significant differences between groups in terms of the number of prescriptions, duration, and whether the patient was on other medications or not. These results have been confirmed by regression analysis, where male and younger ages represented a significant contributing factor to MDA compared to psychosis, 95 % CI: 8 x107 (8 x107 - 8 x107) and 0.943 (0.900---0.987), respectively.

Conclusion

Quetiapine was prescribed more frequently in MDA patients and younger individuals. Low dose was predominant in those patients, indicating a probability of drug abuse.

Combined effects of methadone and quetiapine on respiratory rate, haemodynamic variables, and temperature in conscious rats

Fatal poisonings where both methadone and quetiapine are detected post-mortem occurs frequently in legal autopsy cases. It is unclear whether quetiapine increases the risk of fatal methadone poisoning or if it is merely detected due to widespread use. We hypothesized that methadone and quetiapine would have additive toxic effects on respiratory rate, blood pressure, and the QTc-interval. To investigate this hypothesis, we used telemetry implants for measurements of respiratory rate, haemodynamic variables, the velocity of blood pressure changes, temperature, and movement in conscious, freely moving male Wistar rats aged 12-13 weeks. The combined effects of three accumulative i.p. doses of methadone (2.5, 10, 15 mg/kg) and quetiapine (3, 10, 30 mg/kg) were compared to rats treated with the same doses of each drug alone, and a vehicle-treated group in a randomized investigator blinded study. No additive effects of quetiapine and methadone on respiratory rate, haemodynamic variables, or movement were observed. However, body temperature was significantly lower by approximately 1.5°C on average in the group treated with both methadone and quetiapine (15 + 30 mg/kg) compared to the other groups. This indicates a synergistic effect of quetiapine and methadone on thermoregulation, which may increase the risk of fatal poisoning. We suggest studying this finding further in human settings.

Quetiapine and olanzapine misuse prevalence in a US general population sample

Introduction

Second-generation antipsychotics (SGA) are associated with misuse potential; however, there are limited data describing the prevalence and characteristics of this misuse. This study was conducted to identify and describe quetiapine and olanzapine misuse among US adults.

Methods

This cross-sectional survey questionnaire was conducted online using Qualtrics research panel aggregator service to identify a quota-based sample of respondents constructed to mimic the general US population aged 18 to 59 years, with regards to gender, geographic region, ethnicity, income, and education level. Misuse was defined as using quetiapine or olanzapine for treatment outside of medical recommendations, for reasons other than a diagnosed medical condition, or obtaining without a prescription. A logistic regression was used to identify factors associated with SGA misuse, incorporating relevant covariates.

Results

Among 1843 total respondents, 229 had a history of quetiapine or olanzapine use. Misuse prevalence was estimated to be 6.3% (95% CI: 5.2, 7.5%). Although most respondents (∼70%) using quetiapine or olanzapine reported doing so to treat a diagnosed medical condition, those misusing them most commonly did so because prescribed medications failed to relieve their symptoms. Misuse was commonly reported (∼50%) concomitantly with opioids, benzodiazepines, or alcohol. Factors significantly associated with quetiapine or olanzapine misuse included employment (OR = 4.64), previous substance use disorder treatment (OR = 2.48), and having riskier attitudes toward medication misuse (OR = 1.23).

Discussion

Misuse of quetiapine and olanzapine, while fairly limited in prevalence, appears to be primarily associated with under-treatment of existing medical conditions.

Clinical Presentation and Management of Acute Dystonia from Drug Abuse or Misuse in Adolescents and Young Adults: A Retrospective Cohort Study in Bangkok, Thailand

Objectives

To describe the clinical presentation of acute dystonia (AD) from drug abuse or misuse, as well as the emergency department (ED) management and outcomes in adolescents and young adults.

Methods

This was a retrospective cohort study of patients aged 10-25 years who were admitted to the ED for AD due to intentional abuse or misuse from January 1, 2014, to June 30, 2017. Data were collected from electronic medical records by three investigators with excellent interrater reliability (0.87).

Results

Sixty-two cases met the criteria with male predominance (85.5%); the mean age was 16.7 years. Perphenazine was the most common cause of AD (38.7%), followed by haloperidol (32.2%). The most common AD manifestations were torticollis (51.6%), oromandibular dystonia (45.2%), and oculogyric crisis (22.6%). Intravenous (IV) diazepam combined with oral trihexyphenidyl and IV diazepam alone were the most frequently used first treatment in our ED (41.7% and 35.0%, respectively). Overall, the improvement rates from IV diazepam alone or combined with trihexyphenidyl ranged from 46.2%-75.0%. These rates were inferior to those observed with IV benztropine (100%) alone or combined with trihexyphenidyl. All patients were treated on an outpatient basis, except for one who was admitted to a pediatric ward.

Conclusions

In recent years, drug-induced AD caused by intentional abuse among adolescents and young adults has become a concern in Thailand. The most common suspected drugs of abuse were first-generation antipsychotics, perphenazine, and haloperidol. The most effective treatment was benztropine.

Antipsychotic Abuse, Dependence, and Withdrawal in the Pediatric Population: A Real-World Disproportionality Analysis

Antipsychotic drugs (APs) aim to treat schizophrenia, bipolar mania, and behavioral symptoms. In child psychiatry, despite limited evidence regarding their efficacy and safety, APs are increasingly subject to off-label use. Studies investigating addictology-related symptoms in young people being scarce, we aimed to characterize the different patterns of AP misuse and withdrawal in children and adolescents relying on the WHO pharmacovigilance database (VigiBase^®, Uppsala Monitoring Centre, Sweden). Using the standardized MedDRA Query 'drug abuse, dependence and withdrawal', disproportionality for each AP was assessed with the reporting odds ratio and the information component. A signal was detected when the lower end of the 95% confidence interval of the information component was positive. Results revealed mainly withdrawal symptoms in infants (under 2 years), intentional misuse in children (2 to 11 years), and abuse in adolescents (12 to 17 years). Olanzapine, risperidone, aripiprazole, and quetiapine were disproportionately reported in all age groups, with quetiapine being subject to a specific abuse signal in adolescents. Thus, in adolescents, the evocation of possible recreational consumption may lead to addiction-appropriate care. Further, in young patients with a history of AP treatment, a careful anamnesis may allow one to identify misuse and its role in the case of new-onset symptoms.

Combined effects of quetiapine and opioids: A study of autopsy cases, drug users and sedation in rats

Fatal opioid poisonings often involve methadone or morphine. This study aimed to elucidate if quetiapine, a widely used sedative antipsychotic medication, may increase the risk of fatal opioid poisoning by additive inhibitory effects on the central nervous system. We used data from 323 cases of fatal methadone or/and morphine poisonings autopsied from 2013 to 2020, a survey of 34 drug users, and performed blinded placebo‐controlled studies in 75 Flinders Resistant Line rats receiving three cumulative intraperitoneal doses of vehicle, methadone (2.5, 10 and 15 mg/kg), morphine (3.75, 15 and 22.5 mg/kg), quetiapine (3, 10 and 30 mg/kg) or quetiapine combined with methadone or morphine. Quetiapine was detected in 20.4% of fatal opioid poisonings with a significantly increased frequency over time, primarily in low or therapeutic concentrations, and was not associated with methadone or morphine concentrations. Use of quetiapine, most commonly in low‐to‐moderate doses to obtain a sleep‐inducing or tranquillizing effect, was reported by 67.6% of survey respondents. In the animal studies, a significant impairment of sedation score, performance on the rotarod and open field mobility was observed in all treatment groups compared with vehicle. However, the effect of quetiapine plus the opioid was not significantly different from that of the opioid alone. Thus, no additive sedative effects were observed in rats. Our results suggest that quetiapine is more often an innocent bystander than a contributor to fatal opioid poisoning. However, the combined effects on other parameters, including blood pressure, cardiac rhythm and respiratory rate, need investigation.

Abuse and misuse of second-generation antipsychotics: an analysis using VigiBaseTM , the World Health Organisation pharmacovigilance database

The study aim was to assess the abuse/misuse potential of second-generation antipsychotics (SGAPs) using VigiBase^TM data. We extracted individual case safety reports (ICSRs) of 'Drug abuse, dependence, and withdrawal' involving SGAPs up to June 2018. We assessed disproportionate reporting by calculating the Information Component (IC), considering the lower end of the 95% credibility interval for IC (IC₀₂₅ ), and the Proportional Reporting Ratio (PRR). We identified 1,683 ICSRs recorded as 'abuse, dependence, and withdrawal' involving SGAPs, mainly quetiapine (n=1,089) and olanzapine (n=209). The disproportional reporting indicators highlighted an association between 'Drug abuse and dependence', and quetiapine, olanzapine, and ziprasidone, as indicated by the IC₀₂₅ (2.263, 0.259, and 1.051, respectively) and PRR values (3.929, 1.020, and 1.334, respectively). The abuse/misuse potential is confirmed for quetiapine and olanzapine and highlighted for the first time for ziprasidone. Physicians should consider these risks when prescribing these antipsychotics, especially to patients with history of drug abuse.

A Comprehensive Investigation of Interactions between Antipsychotic Drug Quetiapine and Human Serum Albumin Using Multi-Spectroscopic, Biochemical, and Molecular Modeling Approaches

Quetiapine (QTP) is a short-acting atypical antipsychotic drug that treats schizophrenia or manic episodes of bipolar disorder. Human serum albumin (HSA) is an essential transport protein that transports hormones and various other ligands to their intended site of action. The interactions of QTP with HSA and their binding mechanism in the HSA-QTP system was studied using spectroscopic and molecular docking techniques. The UV-Vis absorption study shows hyperchromicity in the spectra of HSA on the addition of QTP, suggesting the complex formation and interactions between QTP and HSA. The results of intrinsic fluorescence indicate that QTP quenched the fluorescence of HSA and confirmed the complex formation between HSA and QTP, and this quenching mechanism was a static one. Thermodynamic analysis of the HSA-QTP system confirms the involvement of hydrophobic forces, and this complex formation is spontaneous. The competitive displacement and molecular docking experiments demonstrated that QTP is preferentially bound to HSA subdomain IB. Furthermore, the CD experiment results showed conformational changes in the HSA-QTP system. Besides this, the addition of QTP does not affect the esterase-like activity of HSA. This study will help further understand the credible mechanism of transport and delivery of QTP via HSA and design new QTP-based derivatives with greater efficacy.

Safety concerns on the abuse potential of esketamine: Multidimensional analysis of a new anti-depressive drug on the market

Prominent features of esketamine (e.g., similar mechanism of action as ketamine and target population) require to be vigilant regarding its benefits/risks balance and its risks of abuse in real-life settings. The aim of this study was to review all available pharmacological and clinical data to assess the abuse potential of esketamine shortly after its marketing. This multidimensional study is a quantitative and qualitative analysis of complementary data sources, ranging from preauthorization data (i.e., fundamental pharmacology and clinical trials) to real-life settings data (i.e., pharmacovigilance databases and web forums). According to esketamine pharmacology, its psychoactive effects play a role both in its therapeutic effect and its abuse potential. Only one out of the three short-term efficacy trials found a significant difference between esketamine and placebo in treatment-resistant depression. Beside adverse events that may be sought for abuse purpose (e.g., dissociation, sedation, euphoric mood, hallucination, feeling drunk, and derealization), clinical signs related to substance use disorder (e.g., tolerance, withdrawal syndrome, and drug dependence) and misuse (e.g., off-label use) were also identified in pharmacovigilance databases. Analysis of pharmacovigilance narratives and web forums showed that esketamine psychoactive effects are appreciated by some patients, while they are badly experienced by others. Strict compliance with the market authorization, close monitoring of patients by psychiatrists, and surveillance of any signs of misuse, abuse, or dependence must be part of any treatment course.

Gabapentinoid Pharmacology in the Context of Emerging Misuse Liability

This article will review the epidemiology and pharmacology of gabapentinoids (gabapentin and pregabalin) relevant to their emerging misuse potential and provide guidance for clinical and regulatory management. Gabapentinoids are γ-aminobutyric acid analogues that produce their therapeutic effects by inhibiting voltage-gated calcium channels and decreasing neurotransmitter release. Recently gabapentinoid prescribing and use have increased tremendously. Although traditionally thought to possess a favorable safety profile, gabapentinoid misuse has also risen significantly. Gabapentinoid misuse generally occurs in combination with other substances, most notably opioids, and may be for purposes of eliciting euphoric effects, enhancing the effects of other substances, or self-treating conditions such as withdrawal, pain, anxiety, or insomnia. Given its faster onset, increased bioavailability and potency, and nonsaturable absorption, pregabalin's pharmacokinetics theoretically enhance its misuse liability versus gabapentin. However, gabapentin can produce similar euphoric effects, and epidemiologic studies have identified higher rates of gabapentin misuse in the United States, likely because of greater availability and less regulated prescribing. Although adverse events of gabapentinoid-only ingestion are relatively benign, a growing body of evidence indicates that gabapentinoids significantly increase opioid-related morbidity and mortality when used concomitantly. In addition, significant withdrawal effects may occur on abrupt discontinuation. As a result of these trends, several US states have begun to further regulate gabapentinoid prescribing, reclassifying it as a controlled substance or mandating reporting to local prescription drug-monitoring programs. Although increased regulation of gabapentin prescribing may be warranted, harm reduction efforts and increased patient and provider education are necessary to mitigate this concerning gabapentinoid misuse trend.

Quetiapine, Misuse and Dependency: A Case-Series of Questions to a Norwegian Network of Drug Information Centers

Purpose

The second-generation antipsychotic quetiapine has been associated with misuse and dependency. We aimed to review questions to the Norwegian network of drug information centers concerning this potential drug safety problem.

Methods

We conducted a Boolean search in the database of the Regional Medicines Information and Pharmacovigilance Centres in Norway (RELIS) combining the indexed categories “quetiapine” and “adverse drug reaction” with the text words “misuse” or “dependency”. Question–answer pairs (Q/As) in the full-text, searchable RELIS database were defined as cases. Cases were analyzed for drug safety issues linked to use of quetiapine, including off-label use, polypharmacy and other patient risk factors.

Results

The search resulted in 54 cases. Forty-six cases (85%) were patient-related, and a majority came from physicians working in hospitals. Twenty-nine cases (54%) concerned patients with a history of addiction, 14 cases (26%) had polypharmacy, and off-label use of quetiapine for insomnia was identified in 14 of the cases (26%). Only three of the cases included a specific question about patient dependency of quetiapine, and these cases were all associated with insomnia.

Conclusion

We conclude that our case series from the Norwegian network of drug information centres reflects that quetiapine frequently involves clinical narratives of a history of addiction, polypharmacy or insomnia (off-label use). However, the case series did not reveal new information about the drug’s addictive potential.

Quetiapine and other antipsychotics combined with opioids in legal autopsy cases: A random finding or cause of fatal outcome?

Opioid poisoning is a frequent cause of death in drug addicts and occurs with opioid treatment. Quetiapine is often found in forensic autopsies and may increase the risk of fatal opioid poisoning by enhancing sedation, respiratory depression, hypotension and QT prolongation. We systematically searched for studies of acute toxicity of quetiapine or other antipsychotics combined with morphine or methadone. Case reports describing toxicity of quetiapine combined with morphine or methadone were also included. We retrieved one human study that observed pharmacokinetic interaction between quetiapine and methadone, and 16 other human studies. Fourteen investigated the combination of droperidol and morphine in treatment doses, and some indicated an additive sedative effect. Five animal studies with acepromazine in combination with morphine or methadone were located and indicated an additive effect on sedation and hypotension. Six forensic case reports in which death could have been caused solely by quetiapine, the opioid, or other drugs were found. Thus, acute toxicity of quetiapine combined with morphine or methadone has not been studied. Because of quetiapine's effects on alpha-adrenoceptors, muscarinic and histamine receptors, human ether-a-go-go-channels and methadone kinetics, we suggest further research to clarify if the indicated additive effects of opioids and droperidol or acepromazine are also true for quetiapine.

Nitrous oxide misuse reported to two United States data systems during 2000-2019

Background: Nitrous oxide may be misused due to its euphoric, dissociative, and hallucinogenic effects. Nitrous oxide misuse has been reported to be increasing.Objective: The objective of this study is to describe nitrous oxide misuse reported to two United States (US) data systems.Methods: Cases were nitrous oxide misuse during 2000-2019 reported to the National Electronic Injury Surveillance System (NEISS), which collects data on consumer product-related injuries treated in US emergency departments (EDs), and the Food and Drug Administration Adverse Event Reporting System (FAERS), which collects reports of adverse events involving drugs and other biologic products. The distribution of cases was determined for selected variables.Results: Of the 26 NEISS cases, the mean annual number of cases was 0.5 (range 0-2) during 2000-2013 and 3.2 (range 1-5) during 2014-2019. The patients were 92.3% age 13-39 years and 76.9% male. The patient was treated or examined and released from the ED in 84.6% of the cases. Of the 128 FAERS cases, the mean annual number of cases was 0.4 (range 0-2) during 2000-2013 and 20.3 (range 10-34) during 2014-2019. The patients were 90.2%% age 13-39 years and 77.3% male. A serious classification was assigned to 97.7% of the cases.Conclusions: Nitrous oxide misuse reported to NEISS and FAERS both increased during 2000-2019, particularly after 2013. The majority of patients were age 13-39 years and male. Most NEISS patients were treated or examined and released from the ED.

Focus on Clozapine Withdrawal- and Misuse-Related Cases as Reported to the European Medicines Agency (EMA) Pharmacovigilance Database

BACKGROUND

Clozapine is of high clinical relevance for the management of both treatment-resistant schizophrenia and psychotic disturbances with concurrent drug misuse. Although the molecule presents with a range of well-known side-effects, its discontinuation/withdrawal syndrome has been only anecdotally described.

AIMS

the 2005-2018 European Medicines Agency (EMA) dataset of Adverse Drug Reactions (ADRs) was analyzed to identify and describe possible clozapine withdrawal- and misuse-/abuse-/dependence-related issues.

METHOD

A descriptive analysis of clozapine-related ADRs was performed when available, data on ADRs' outcome, dosage, and possible concomitant drug(s) were considered.

RESULTS

Out of 11,847 clozapine-related ADRs, some 599 (5.05%) were related to misuse/abuse/dependence/withdrawal issues, including 258 withdrawal-related (43.1%); 241 abuse-related (40.2%); and 80 intentional product misuse-related (13.3%) ADRs. A small number of overdose- and suicide-related ADRs were reported as well. Clozapine was typically (69.2%) identified alone, and most (84.7%) fatalities/high-dosage intake instances were reported in association with a history of substance abuse.

CONCLUSIONS

Previous suggestions about the possibility of a clozapine discontinuation/withdrawal occurrence are here supported, but further studies are needed. However, the misuse/abuse cases here identified might be difficult to interpret, given the lack of studies highlighting the possible recreational use of clozapine. The high-dosage intake, fatal outcomes and clozapine/polydrug abuse issues reported here may, however, be a reason for concern.

Hypoglycemia Associated with Antibiotics Alone and in Combination with Sulfonylureas and Meglitinides: An Epidemiologic Surveillance Study of the FDA Adverse Event Reporting System (FAERS)

INTRODUCTION

Fluoroquinolones, clarithromycin, linezolid, tigecycline, cefditoren, doxycycline, and trimethoprim-sulfamethoxazole are known to be associated with hypoglycemia, but few studies have considered concomitant glucose-lowering medications.

OBJECTIVE

The objective of this study was to evaluate the association between hypoglycemia and antibiotics using the US Food and Drug Administration Adverse Event Reporting System (FAERS), while accounting for concomitant glucose-lowering medications including sulfonylureas and meglitinides.

METHODS

FAERS reports from 1 January 2004 to 31 December 2017 were included in the study. Reporting odds ratios (RORs) and corresponding 95% confidence intervals (CIs) for the association between antibiotics and hypoglycemia were calculated. An association was considered to be statistically significant when the lower limit of the 95% CI was > 1.0.

RESULTS

A total of 2,334,959 reports (including 18,466 hypoglycemia reports) were considered, after inclusion criteria were applied. Statistically significant hypoglycemia RORs (95% CI) for antibiotics were: cefditoren 14.03 (8.93-22.03), tigecycline 3.32 (1.95-5.65), clarithromycin 2.41 (1.89-3.08), ertapenem 2.07 (1.14-3.75), moxifloxacin 2.06 (1.59-2.65), levofloxacin 1.66 (1.37-2.01), and linezolid 1.54 (1.07-2.20). After adjusting for concomitant sulfonylureas and meglitinides, the following antibiotics were still significantly associated with hypoglycemia: cefditoren 14.25 (9.08-22.39), tigecycline 3.34 (1.96-5.68), ertapenem 1.93 (1.03-3.60), and clarithromycin 1.56 (1.15-2.11).

CONCLUSION

In many patients, antibiotics, including fluoroquinolones, are associated with hypoglycemia when they are also taking sulfonylureas or meglitinides. Cefditoren, tigecycline, ertapenem, and clarithromycin are associated with hypoglycemia even if not taken with sulfonylureas or meglitinides. The association between ertapenem and hypoglycemia has not been previously reported.

Rhabdomyolysis Associations with Antibiotics: A Pharmacovigilance Study of the FDA Adverse Event Reporting System (FAERS)

Introduction: Daptomycin, macrolides, trimethoprim-sulfamethoxazole, linezolid, fluoroquinolones, and cefdinir are known to be associated with rhabdomyolysis. Other antibiotics may also lead to rhabdomyolysis, but no study has systemically compared rhabdomyolysis associations for many available antibiotics. Objectives: The objective of this study was to evaluate the association between rhabdomyolysis and many available antibiotics using the FDA Adverse Event Report System (FAERS). Methods: FAERS reports from January 1, 2004 to December 31, 2017 were included in the study. The Medical Dictionary for Regulatory Activities (MedDRA) was used to identify rhabdomyolysis cases. Reporting Odds Ratios (RORs) and corresponding 95% confidence intervals (95%CI) for the association between antibiotics and rhabdomyolysis were calculated. An association was considered statistically significant when the lower limit of the 95%CI was greater than 1.0. Results: A total of 2,334,959 reports (including 7,685 rhabdomyolysis reports) were considered, after inclusion criteria were applied. Daptomycin had the greatest proportion of rhabdomyolysis reports, representing 5.5% of all daptomycin reports. Statistically significant rhabdomyolysis RORs (95% CI) for antibiotics were (in descending order): daptomycin 17.94 (14.08-22.85), cefditoren 8.61 (3.54-20.94), cefaclor 7.16 (2.28-22.49), erythromycin 5.93 (3.17-11.10), norfloxacin 4.50 (1.44-14.07), clarithromycin 3.95 (2.77-5.64), meropenem 3.19 (1.51-6.72), azithromycin 2.94 (1.96-4.39), cefdinir 2.84 (1.06-7.62), piperacillin-tazobactam 2.61 (1.48-4.61), trimethoprim-sulfamethoxazole 2.53 (1.52-4.21), linezolid 2.49 (1.47-4.21), ciprofloxacin 2.10 (1.51-2.92). Conclusions: This study confirms prior evidence for rhabdomyolysis associations with daptomycin, macrolides, trimethoprim-sulfamethoxazole, linezolid, fluoroquinolones, and cefdinir. This study also identifies previously unknown rhabdomyolysis associations with meropenem, cefditoren, cefaclor, and piperacillin-tazobactam.