TEENAGERS AND ILLICIT DRUG-USE - EXPANDING THE USER VS NONUSER DICHOTOMY

The present study examines proximal and distal factors associated with the use and non-use of illegal substances within a sample of 860 teenagers in North Wales. Arguing that there is predictive utility in expanding the traditional 'users vs non-users' design dichotomy, four groups are identified-resistant and vulnerable non-users and experimental and repeated users. 'Person' variables (life satisfaction, deviance, hopelessness and drug-related attributions) appeared to primarily differentiate the vulnerable group from their resistant counterparts and identify this, as yet non-using group, with user samples. It is suggested that these variables might represent 'risk' factors for illicit substance use and that the group design employed suggests they precede, rather than follow as a consequence of, illicit drug use. Like their resistant counterparts however, the vulnerable group are differentiated from user samples on some lifestyle and context indices. It is argued that these represent 'protective' influences in an otherwise at-risk group of non-users. Variables associated with an escalation of illicit drug use are discussed in considering the differences between the experimental and repeated user groups. Apart from the more proximal factor of drug-related attributions, 'person' variables appeared less involved here. Repeated users did however, tend to use a greater number of drugs, have a greater proportion of friends who also used illegal substances and significantly fewer had a Welsh cultural identity.

Non-steroidal anti-inflammatory drug and aspirin use and the risk of head and neck cancer

Background: Evidence for non-steroidal anti-inflammatory drugs (NSAIDs) preventing head and neck cancer (HNC) is inconclusive; however, there is some suggestion that aspirin may exert a protective effect.

Methods: Using data from the United States National Cancer Institute Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, we examined the association between aspirin and ibuprofen use and HNC.

Results: Regular aspirin use was associated with a significant 22% reduction in HNC risk. No association was observed with regular ibuprofen use.

Conclusion: Aspirin may have potential as a chemopreventive agent for HNC, but further investigation is warranted.

Physical characterisation and component release of poly(vinyl alcohol)-tetrahydroxyborate hydrogels and their applicability as potential topical drug delivery systems

Poly(vinyl alcohol)-tetrahydroxyborate (PVA-THB) hydrogels are dilatant formulations with potential for topical wound management. To support this contention, the physical properties, rheological behaviour and component release of candidate formulations were investigated. Oscillatory rheometry and texture profile analysis were used at room temperature and 37 °C. Results showed that it was possible to control the rheological and textural properties by altering component concentration and modifying the type of PVA polymer used. Hydrogels made using PVA grades with higher degrees of hydrolysis displayed favourable characteristics from a wound healing perspective. In vitro release of borate and PVA were assessed in order to evaluate potential clinical dosing of free species originating from the hydrogel structure. Component diffusion was influenced by both concentration and molecular weight, where relevant, with up to 5% free PVA cumulative release observed after 30 min. The results of this study demonstrated the importance of poly(vinyl alcohol) selection for ensuring appropriate gel formation in PVA-THB hydrogels. The benefits of higher degrees of hydrolysis, in particular, included lower excipient release and reduced bioadhesion. The unique physical characteristics of these hydrogels make them an appealing delivery vehicle for chronic and acute wound management purposes.

Non-steroidal anti-inflammatory drug use and cervical cancer risk: a case-control study using the Clinical Practice Research Datalink

Non-steroidal anti-inflammatory drugs (NSAIDs) have many anticarcinogenic properties via the inhibition of cyclooxygenase 2 (COX-2). Only one study, a cohort study examining risk of all cancers, investigated their role in cervical cancer with inconsistent findings between non-aspirin NSAIDs and aspirin. The aim of this study was to further investigate NSAID/aspirin use and cervical cancer risk.

Microneedle-Iontophoresis Combinations for Enhanced Transdermal Drug Delivery

It has recently been proposed that the combination of skin barrier impairment using microneedles (MNs) coupled with iontophoresis (ITP) may broaden the range of drugs suitable for transdermal delivery as well as enabling the rate of delivery to be achieved with precise electronic control. However, few reports exist on the combination of ITP with in situ drug-loaded polymeric MN delivery systems. Our in vitro permeation studies revealed that MN enhances transdermal drug delivery. The combination of dissolving MN and ITP did not further enhance the extent of delivery of the low molecular weight drug ibuprofen sodium after short application periods. However, the extent of peptide/protein delivery was significantly enhanced when ITP was used in combination with hydrogel-forming MN arrays. As such, hydrogel-forming MN arrays show promise for the electrically controlled transdermal delivery of biomacromolecules in a simple, one-step approach, though further technical developments will be necessary before patient benefit is realized.

Fast-drying multi-laminate bioadhesive films for transdermal and topical drug delivery

No bioadhesive patch-based system is currently marketed. This is despite an extensive number of literature reports on such systems detailing their advantages over conventional pressure sensitive adhesive-based patches in wet environments and describing successful delivery of a diverse array of drug substances. This lack of proprietary bioadhesive patches is largely due to the fact that such systems are exclusively water-based, meaning drying is difficult. In this paper we describe, for the first time, a novel multiple lamination method for production of bioadhesive patches. In contrast to patches produced using a conventional casting approach, which took 48 hours to dry, bioadhesive films prepared using the novel multiple lamination method were dried in 15?min and were folded into formed patches in a further 10?min. Patches prepared by both methods had comparable physicochemical properties. The multiple lamination method allowed supersaturation of 5-aminolevulinic acid to be achieved in formed patch matrices. However, drug release studies were unable to show an advantage for supersaturation with this particular drug, due to its water high solubility. The multiple lamination method allowed greater than 90% of incorporated nicotine to remain within formed patches, in contrast to the 48% achieved for patches prepared using a conventional casting approach. The procedure described here could readily be adapted for automation by industry. Due to the reduced time, energy and ensuing finance now required, this could lead to bioadhesive patch-based drug delivery systems becoming commercially viable. This would, in turn, mean that pathological conditions occurring in wet or moist areas of the body could now be routinely treated by prolonged site-specific drug delivery, as mediated by a commercially produced bioadhesive patch.

Triose phosphate isomerase from the blood fluke Schistosoma mansoni:Biochemical characterisation of a potential drug and vaccine target

The glycolytic enzyme triose phosphate isomerase from Schistosoma mansoni is a potential target for drugs and vaccines. Molecular modelling of the enzyme predicted that a Ser-Ala-Asp motif which is believed to be a helminth-specific epitope is exposed. The enzyme is dimeric (as judged by gel filtration and cross-linking), resistant to proteolysis and highly stable to thermal denaturation (melting temperature of 82.0°C). The steady-state kinetic parameters are high (Km for dihydroxyacetone phosphate is 0.51mM; Km for glyceraldehyde 3-phosphate is 1.1mM; kcat for dihydroxyacetone phosphate is 7800s(-1) and kcat for glyceraldehyde 3-phosphate is 6.9s(-1)).

Effect of the P-glycoprotein inhibitor, R(+)-verapamil on the drug susceptibility of a triclabendazole-resistant isolate of Fasciola hepatica

A study has been carried out to investigate whether the action of triclabendazole (TCBZ) against Fasciola hepatica is altered by the inhibition of P-glycoprotein (Pgp)-linked drug efflux pumps. The Sligo TCBZ-resistant and Cullompton TCBZ-susceptible fluke isolates were used for these experiments and the Pgp inhibitor selected was R(+)-verapamil [R-VPL]. In the first experiment, flukes were initially incubated for 2 h in R-VPL (100 µM), then incubated for a further 22 h in R-VPL+triclabendazole sulphoxide (TCBZ.SO) (50 µg/ml, or 0.1327 µM). For controls, flukes were incubated for 24 h in R-VPL and TCBZ.SO on their own. In a second experiment, flukes were removed from the incubation media following cessation of movement. In the third experiment, Sligo flukes were incubated in lower concentrations of R-VPL (10 µM) and TCBZ.SO (15 µg/ml, or 0.0398 µM). Morphological changes resulting from drug treatment and following Pgp inhibition were assessed by means of scanning electron microscopy. Incubation in R-VPL alone had minimal effect on either isolate. After treatment with TCBZ.SO alone, there was greater surface disruption to the Cullompton than Sligo isolate. However, combined treatment of R-VPL+TCBZ.SO led to more severe surface changes to the Sligo isolate than with TCBZ.SO on its own; this potentiation of drug activity was not seen with the Cullompton isolate. The phenomenon was evident at both concentrations of TCBZ.SO. Inclusion of R-VPL in the incubation medium also reduced the time taken for the flukes to become inactive; again, this effect was more distinct with the Sligo isolate. The results of this study support the concept of altered drug efflux in TCBZ-resistant flukes and indicate that drug transporters may play a role in the development of drug resistance.