Formulation and Scale-up of Delamanid Nanoparticles via Emulsification for Oral Tuberculosis Treatment

Delamanid (DLM) is a hydrophobic small molecule therapeutic used to treat drug-resistant tuberculosis (DR-TB). Due to its hydrophobicity and resulting poor aqueous solubility, formulation strategies such as amorphous solid dispersions (ASDs) have been investigated to enhance its aqueous dissolution kinetics and thereby improve oral bioavailability. However, ASD formulations are susceptible to temperature- and humidity-induced phase separation and recrystallization under harsh storage conditions typically encountered in areas with high tuberculosis incidence. Nanoencapsulation represents an alternative formulation strategy to increase aqueous dissolution kinetics while remaining stable at elevated temperature and humidity. The stabilizer layer coating the nanoparticle drug core limits the formation of large drug domains by diffusion during storage, representing an advantage over ASDs. Initial attempts to form DLM-loaded nanoparticles via precipitation-driven self-assembly were unsuccessful, as the trifluoromethyl and nitro functional groups present on DLM were thought to interfere with surface stabilizer attachment. Therefore, in this work, we investigated the nanoencapsulation of DLM via emulsification, avoiding the formation of a solid drug core and instead keeping DLM dissolved in a dichloromethane dispersed phase during nanoparticle formation. Initial emulsion formulation screening by probe-tip ultrasonication revealed that a 1:1 mass ratio of lecithin and HPMC stabilizers formed 250 nm size-stable emulsion droplets with 40% DLM loading. Scale-up studies were performed to produce nearly identical droplet size distribution at larger scale using high-pressure homogenization, a continuous and industrially scalable technique. The resulting emulsions were spray-dried to form a dried powder, and in vitro dissolution studies showed dramatically enhanced dissolution kinetics compared to both as-received crystalline DLM and micronized crystalline DLM, owing to the increased specific surface area and partially amorphous character of the DLM-loaded nanoparticles. Solid-state NMR and dissolution studies showed good physical stability of the emulsion powders during accelerated stability testing (50 °C/75% RH, open vial).

Formulation of pH-Responsive Methacrylate-Based Polyelectrolyte-Stabilized Nanoparticles for Applications in Drug Delivery

pH-responsive polyelectrolytes, including methacrylate-based anionic copolymers (MACs), are widely used as enteric coatings and matrices in oral drug delivery. Despite their widespread use in these macroscopic applications, the molecular understanding of their use as stabilizers for nanoparticles (NPs) is lacking. Here, we investigate how MACs can be used to create NPs for therapeutic drug delivery and the role of MAC molecular properties on the assembly of NPs via flash nanoprecipitation. The NP size is tuned from 59 to 454 nm by changing the degree of neutralization, ionic strength, total mass concentration, and the core-to-MAC ratio. The NP size is determined by the volume of hydrophilic domains on the surface relative to the volume of hydrophobic domains in the core. We calculate the dimensions of the hydrophobic NP core relative to the thickness of the polyelectrolyte layer over a range of ionizations. Importantly, the results are shown to apply to both high-molecular-weight polymers as core materials and small-molecule drugs. The pH responsiveness of MAC-stabilized NPs is also demonstrated. Future development of polyelectrolyte copolymer-stabilized nanomedicines will benefit from the guiding principles established in this study.

Sensors in a Flash! Oxygen Nanosensors for Microbial Metabolic Monitoring Synthesized by Flash Nanoprecipitation

Flash nanoprecipitation (FNP) is an efficient and scalable nanoparticle synthesis method that has not previously been applied to nanosensor fabrication. Current nanosensor fabrication methods have traditionally exhibited poor replicability and consistency resulting in high batch-to-batch variability, highlighting the need for a more tunable and efficient method such as FNP. We used FNP to fabricate nanosensors to sense oxygen based on an oxygen-sensitive dye and a reference dye, as a tool for measuring microbial metabolism. We used fluorescence spectroscopy to optimize nanosensor formulations, calibrate the nanosensors for oxygen concentration determination, and measure oxygen concentrations through oxygen-sensitive dye luminescence. FNP provides an effective platform for making sensors capable of responding to oxygen concentration in gas-bubbled solutions as well as in microbial environments. The environments we tested the sensors in arePseudomonas aeruginosa biofilms andSaccharomyces cerevisiae liquid cultures─both settings where oxygen concentration is highly dependent on microbial activity. With FNP now applied to nanosensor fabrication, future nanosensor applications can take advantage of improved product quality through better replicability and consistency while maintaining the original function of the nanosensor.

An orienting response model of eye movement desensitization

Dyck's (Journal of Behavior Therapy and Experimental Psychiatry, 1993) conditioning model of EMD provides a useful description of failure of habituation in post-traumatic stress disorder, but may not account for some common EMD phenomena. An alternative model proposes that the therapist's waving hand--in the presence of a trauma-related cortical set--triggers an intense orienting response (OR). Intrinsic effects of the OR facilitate continuing attention to the memory without avoidance, and provide for effective input of new trauma-related information. The person's neuronal model of the trauma alters to reflect his survival and current safety--as true outcome of the trauma--and associated conditioned responses extinguish. Proposals for experimental evaluation of the model are described.

A trial of eye movement desensitization compared to image habituation training and applied muscle relaxation in post-traumatic stress disorder

Thirty-six patients with PTSD were randomly allocated to individual treatment with imaginal exposure (image habituation training -- IHT), or applied muscle relaxation (AMR) or eye movement desensitization (EMD). Assessment by a blind independent rater and self-report instruments applied pre and posttreatment and at 3-month follow-up indicated that all groups improved significantly compared with a waiting list and that treatment benefits were maintained at follow-up. Despite a failure to demonstrate differences among groups, there was some suggestion that immediately after treatment EMD was superior for intrusive memories.

Behavior completion versus stimulus control in compulsive gambling. Implications for behavioral assessment

Twenty subjects were randomly allocated to receive either imaginal relaxation (IR) or imaginal desensitization (ID) to reduce compulsive gambling. As predicted from a behavioral completion model, but not a stimulus control model, subjects' response to IR was comparable with that to ID. Also as predicted, response correlated with subjects' levels of tension following treatment. Detailed assessment of the situations in which subjects' gambling occurred was not necessary for effective IR therapy. The result established the treatment validity of the assessment used, this study being the first to compare the treatment validity of different behavioral assessments. The finding that manipulation of an organismic variable level of arousal is as effective as a manipulation of a stimulus variable in the treatment of compulsive gambling supports the trend among behavior therapists to place more emphasis on the importance of organismic variables as determinants of pathological behaviors.

A survey of practising psychiatrists' views on treatment of the depressions

The views of practising psychiatrists on treatment of the depressions were investigated as part of a Quality Assurance Project. A one in six random sample of all Australian psychiatrists was mailed a questionnaire. This asked for treatment recommendations for each of five case descriptions of patients with depression. Respondents were asked to code their treatment plans from a glossary listing possible treatments for depression: 85% of the sample responded. Tricyclic antidepressants were the treatment of choice for two cases of endogenous depression, electroconvulsive therapy (ECT) being recommended when psychotic features were present or when drug therapy had failed. Psychotherapies were the treatment of choice for cases with neurotic features, drugs being recommended when improvement with psychotherapy did not occur.

Reduced P200 latency and allusive thinking: an auditory evoked potential index of a cognitive predisposition to schizophrenia?

Auditory evoked potentials were recorded in healthy medical students who were grouped according to whether they obtained a high or low score on an Object Sorting Test (OST), on which schizophrenics also obtain high scores. High-OST scoring male students compared to Low-OST scoring male students showed reduced P200 latency. This finding was replicated in a second study of medical students. The authors believe these results support the hypothesis that schizophrenic thought disorder and an equivalent loosening of thinking in nonschizophrenic populations (allusive thinking) have a neurophysiological basis in common, namely a relative weakness of inhibition operating on cortical and subcortical structures.

Expectancy, covert sensitization and imaginal desensitization in compulsive sexuality

Twenty subjects were randomly allocated to receive either imaginal desensitization (ID) or covert sensitization (CS) to reduce compulsive anomalous sexual behaviours. It was predicted from a behavioural completion model of compulsive urges, that patients' response to ID would be at least as good as their response to CS and would correlate with reduction in their general levels of tension following treatment. These predictions were supported. Correlations between patients' expectancies of treatment success and their response were of moderate strength for expectancy measures taken following the first session of both treatments, but much stronger for expectancy measures following the last session of ID. It was suggested that patients experienced a specific response during the further sessions of ID, which enabled them to improve their prediction of response. As aversive therapies remain the standard behavioural therapy for sexual paraphilias, the finding of the present study that imaginal desensitization without traumatic imagery or aversive physical stimuli is at least as effective would seem to require urgent replication, if only on ethical grounds.

Sexual orientation and consistency of sexual identity

The semantic confusion in the use of the terms sexual and gender identity and role is discussed. Theories concerning the development of the sense of sexual identity in normals have been based largely on the sense of sexual identity in sexually deviant subjects. It is suggested that such subjects may have a stronger and more consistent sense of sexual identity than subjects unaware of sexually deviant impulses. Male medical students in two consecutive years anonymously completed a questionnaire concerning their sexual orientation, preference, role, and identity. In both years, students aware of a homosexual component answered the items investigating their sexual identity with greater consistency than did the students unaware of a homosexual component.

Controlled comparison of aversive therapy and imaginal desensitization in compulsive gambling

Twenty compulsive gamblers were randomly allocated, half to receive aversion-relief therapy and half to receive imaginal desensitization; both groups were followed-up for one year. Compared with those who received aversion-relief, gamblers who received imaginal desensitization reported a significantly greater reduction of gambling urge and behaviour; they also showed a significant reduction in trait anxiety at one year and in state anxiety at one month and one year following treatment. A high level of state anxiety at one month following treatment predicted failure to respond to treatment at one year in the subjects who received imaginal desensitization, but not in those who received aversion-relief. The relationship between reduction in anxiety and in gambling urge in response to imaginal desensitization was predicted from the theory that compulsive gambling is driven by aversive tension.

Creativity, divergent and allusive thinking in students and visual artists

Visual artists of acknowledged creativity but not students with divergent thinking showed allusive (loose) thinking on an Object Sorting Test. It was concluded that high but not low level creativity in some fields may be associated with a predisposition to schizophrenia.

Bisexual feelings and opposite-sex behavior in male Malaysian medical students

The sexual identity of 65 Malaysian male medical students was investigated by anonymous questionnaire. Of these students, 40% were aware of homosexual feelings prior to age 15 years, and 16% were so aware currently. There were correlations between current homosexual feelings and feminine sex dimorphic behavior during childhood and between current homosexual feelings and feminine gender identity. The results are discussed in light of results of a similar questionnaire completed by 138 male medical students in Sydney, Australia.

Auditory hallucinations and the Verbal Transformation Effect

In an attempt to replicate findings reported by Slade (1976), 12 hallucinating and 12 non-hallucinating shcizophrenic subjects were compared on tests of verbal ability, personality and mental imagery variables and the Verbal Transformation Effect. No significant differences between the groups was demonstrated. When the data from both groups of schizophrenics were combined, a significant correlation was found between 2 measures of the Verbal Transformation Effect and the P-score of the Eysenck Personality Questionnaire.

Dichotic listening and allusive thinking

Previous work suggests that allusive thinkers have a broader attentional process associated with weak central inhibition. The method of dichotic stimulation was used to investigate this concept. Sixty-three university students completed a battery of tests including 2 dichotic listening tasks. The Object Sorting Test was used as a measure of allusive thinking. Allusive thinkers showed a trend towards impaired shadowing performance. Mislabelling of shadow as distractor words and vice versa, on recall and recognition tasks, showed the strongest correlation with allusive thinking. Such mislabelling was considered to reflect impaired discrimination learning, and provides further support for a hypothesis relating allusive thinking to weak Pavlovaian central inhibition.

Allusive thinking, the Word Halo and verbosity

The concept of allusive thinking is briefly reviewed and a Pavlovian model of thinking advanced. It is hypothesized that allusive, as compared with non-allusive thinkers, have a broader but less intense attention process associated with weaker inhibition. From this model it was predicted that on word tests which require judgements of similarity of meaning, allusive thinkers would tend to choose more remote or unusual words as similar in meaning. The Word Halo Test and the Word Sorting Test were administered to 63 university students using the Object Sorting Test as a measure of allusive thinking. The prediction that allusive thinkers would choose more unusual words as similar in meaning was supported. A tendency for allusive thinkers to be more verbose than non-allusive thinkers was also noted.