Should topical opioid analgesics be regarded as effective and safe when applied to chronic cutaneous lesions?

Objectives: The induction of analgesia for many chronic cutaneous lesions requires treatment with an opioid analgesic. In many patients suffering with these wounds such drugs are either contraindicated or shunned because of their association with death. There are now case reports involving over 100 patients with many different types of chronic superficial wounds, which suggest that the topical application of an opioid in a suitable gel leads to a significant reduction in the level of perceived pain. Key findings: Some work has been undertaken to elucidate the mechanisms by which such a reduction is achieved. To date there have been no proven deleterious effects of such an analgesic system upon wound healing. Although morphine is not absorbed through the intact epidermis, an open wound provides no such barrier and for large wounds drug absorption can be problematic. However, for most chronic cutaneous lesions, where data has been gathered, the blood levels of the drug applied ranges from undetectable to below that required for a systemic effect. Summary If proven, the use of opioids in this way would provide adequate analgesia for a collection of wounds, which are difficult to treat in patients who are often vulnerable. Proof of this concept is now urgently required. © 2011 Royal Pharmaceutical Society.

Comparative physical, mechanical and crystallographic properties of a series of gemfibrozil salts

Objectives Understanding the impact of the counterion on the properties of an acidic or basic drug may influence the choice of salt form, especially for less potent drugs with a high drug load per unit dose. The aim of this work was to determine the influence of the hydrogen bonding potential of the counterion on the crystal structure of salts of the poorly soluble, poorly compressible, acidic drug gemfibrozil and to correlate these with mechanical properties. Methods Compacts of the parent drug and the salts were used to determine Young's modulus of elasticity using beam bending tests. Crystal structures were determined previously from X-ray powder diffraction data. Key findings The free acid, tert-butylamine, 2-amino-2-methylpropan-1-ol and 2-amino-2-methylpropan-1, 3-diol salts had a common crystal packing motif of infinite hydrogen-bonded chains with cross-linking between pairs of adjacent chains. The tromethamine (trsi) salt, with different mechanical properties, had a two-dimensional sheet-like network of hydrogen bonds, with slip planes, forming a stiffer compact. Conclusions The type of counter ion is important in determining mechanical properties and could be selected to afford slip and plastic deformation. © 2010 Royal Pharmaceutical Society of Great Britain.

Synthesis and evaluation of N1-substituted-3-propyl-1,4-benzodiazepine-2-ones as cholecystokinin (CCK2) receptor ligands

A novel synthetic approach towards N1-alkylated 3-propyl-1,4-benzodiazepines was developed in five synthetic steps from 2-amino-4-chlorobenzophenone, in which the N-oxide 4 served as a key intermediate. The structure-activity relationship optimization of this 3-prophyl-1,4-benzodiazepine template was carried out on the N1-position by selective alkylation reactions and resulted in a ligand with an improved affinity on the cholecystokinin (CCK2) receptor. The N-allyl-3-propyl-benzodiazepine 6d displayed an affinity towards the CCK2 (CCK-B) receptor of 170 nM in a radiolabelled receptor-binding assay. The anxiolytic activity of this allyl-3-propyl-1,4-benzodiazepine 6d was subsequently determined in in-vivo psychotropic assays. This novel ligand had ED50 values of 4.7 and 5.2 mg kg-1 in the black and white box test and the x-maze, respectively, and no significant sedation/muscle relaxation was observed.

Structure and activity in assessing antioxidant activity in vitro and in vivo:a critical appraisal illustrated with the flavonoids

Structure–activity relationships are indispensable to identify the most optimal antioxidants. The advantages of in vitro over in vivo experiments for obtaining these relationships are, that the structure is better defined in vitro, since less metabolism takes place. It is also the case that the concentration, a parameter that is directly linked to activity, is more accurately controlled. Moreover, the reactions that occur in vivo, including feed-back mechanisms, are often too multi-faceted and diverse to be compensated for during the assessment of a single structure–activity relationship. Pitfalls of in vitro antioxidant research include: (i) by definition, antioxidants are not stable and substantial amounts of oxidation products are formed and (ii) during the scavenging of reactive species, reaction products of the antioxidants accumulate. Another problem is that the maintenance of a defined concentration of antioxidants is subject to processes such as oxidation and the formation of reaction products during the actual antioxidant reaction, as well as the compartmentalization of the antioxidant and the reactive species in the in vitro test system. So determinations of in vitro structure-activity relationships are subject to many competing variables and they should always be evaluated critically. (c) 2005 Published by Elsevier B.V.

Cell passage-associated transient high oxygenation causes a transient decrease in cellular glutathione and affects T cell responses to apoptotic and mitogenic stimuli

Routine cell line maintenance involves removal of waste products and replenishment of nutrients via replacement of cell culture media. Here, we report that routine maintenance of three discrete cell lines (HSB-CCRF-2 and Jurkat T cells, and phaeo-chromocytoma PC12 cells) decreases the principal cellular antioxidant, glutathione, by up to 42% in HSB-CCRF-2 cells between 60 and 120 min after media replenishment. However, cellular glutathione levels returned to baseline within 5 h after passage. The decrease in glutathione was associated with modulation of the response of Jurkat T cells to apoptotic and mitogenic signals. Methotrexate-induced apoptosis over 16 h, measured as accumulation of apoptotic nucleoids, was decreased from 22 to 17% if cells were exposed to cytotoxic agent 30 min after passage compared with cells exposed to MTX in the absence of passage. In contrast, interleukin-2 (IL-2) production over 24 h in response to the toxin phytohaemagglutinin (PHA), was increased by 34% if cells were challenged 2 h after passage compared with PHA treatment in the absence of passage. This research highlights the presence of a window of time after cell passage of non-adherent cells that may lead to over- or under-estimation of subsequent cell responses to toxins, which is dependent on cellular antioxidant capacity or redox state. © 2007 Elsevier B.V. All rights reserved.

The effect of selected water-soluble excipients on the dissolution of paracetamol and ibuprofen

The purpose of this investigation was to study the dissolution behavior of paracetamol and ibuprofen in the presence of a range of selected potential excipients. First, a pH-solubility profile was generated for both drugs, and the effect of changing hydrodynamic conditions on the intrinsic dissolution rate was investigated. It was established that both drugs dissolved according to the diffusion-layer model. Paracetamol solubility (approximately 20.3 mg mL -1) did not vary from pH 1.2-8.0, corresponding to the in vivo range in the gastrointestinal tract. Ibuprofen had an intrinsic solubility of approximately 0.06 mg mL-1, and pKa was calculated as 4.4. Second, the effects of selected potential excipients (lactose, potassium bicarbonate, sodium bicarbonate, sodium chloride, and tartaric acid) were evaluated by measuring the effect of the inclusion of each additive in the dissolution medium on drug solubility, drug intrinsic dissolution rate, and solution viscosity. The results were evaluated using the diffusion-layer model, and it was determined that for paracetamol, the collected data fitted the model for all the excipients studied. For ibuprofen, it was found that there were differences between the excipients that raised the solution pH above the pK a to those that did not. For the excipients raising the pH above the pKa, the effect on intrinsic dissolution rate was not as high as that expected from the change in drug solubility. It was postulated that this might be due to lack of penetration of the excipient into the drug boundary layer microenvironment. Formulators may calculate the effect of adding an excipient based on solubility increases but may not find the dissolution rate improvement expected. Copyright © 2005 Taylor & Francis Inc.

Synthesis and evaluation of 5-arylated 2(5H)-furanones and 2-arylated pyridazin-3(2H)-ones as anti-cancer agents

Bis-cyclic butenolides, 5-arylated 2(5H)-furanones 6a-c, 7a, b and the 3(2H)-pyridazones 9a-d were prepared by using the aldehyde form of muco halogen acids in electrophilic substitution reactions and in an aldol-like condensation reaction. The cytotoxicity of these simple and bis-cyclic butenolides have been evaluated in tissue culture studies on MAC 13 and MAC 16 murine colon cancer cell lines. The butyl furanone 3 displayed the highest cytotoxicity of 3 μM, as one selected example of a series of dichlorinated pseudoesters. The 5-arylated 2(5H)-furanones 6 and 7 did not show a structure-activity relationship (SAR) depending on the substitution pattern of the aromatic system. An IC50 (concentration inhibiting growth by 50%) was found within a range of 30-50 and 40-50 μM for the MAC 13 and MAC 16 cell lines, respectively. The pyridazine series 9 showed a maximum in-vitro activity for the p-methoxydrivative 9b, having an IC50 of 17 in MAC 13 and 11 μM in MAC 16 cell lines. Selected examples of each series and further novel 2(5H)-furanones such as the hydrazone 5 and the hydantoin 8 have been screened in-vivo in mice and the data are presented. For the pyridazines 9a-d, the in-vitro cytotoxicity correlated with an in-vivo inhibition of tumour growth. The ring expansion of the 5-membered 2(5H)-furanone ring system such as 6a into the 6-membered 3(2H)-pyridazone 9b led to an agent with improved antineoplastic properties. On the resistant MAC 16 cell line the pyridazone 9b displayed 52% tumour inhibition in mice at a dose of 50 mg kg-1 compared with 27% for the 5-FU standard.

Effects of glutathione, N-acetyl-cysteine, α-lipoic acid and dihydrolipoic acid on the cytotoxicity of a 2-pyridylcarboxamidrazone antimycobacterial agent in human mononuclear leucocytes in vitro

A series of antioxidants was used to explore the cytotoxicity of one particularly toxic antimycobacterial 2-pyridylcarboxamidrazone anti-tuberculosis agent against human mononuclear leucocytes (MNL), in comparison with isoniazid (INH) to aid future compound design. INH caused a significant reduction of nearly 40% in cell recovery compared with control (P < 0.0001), although the co-incubation with either glutathione (GSH, 1 mM) or (NAC, 1 mM) showed abolition of INH toxicity. In contrast, the addition of GSH or NAC 1 h after INH failed to protect the cells from INH toxicity (P < 0.0001). The 2-pyridyl-carboxamidrazone 'Compound 1' caused a 50% reduction in cell recovery compared with control (P < 0.001), although this was abolished by the presence of either GSH or NAC. A 1 h post incubation with either NAC or GSH after Compound 1 addition failed to protect the cells from toxicity (P < 0.001). Co-administration of lipoic acid (LA) abolished Compound 1-mediated toxicity, although again, this effect did not occur after LA addition 1 h post incubation with Compound 1 (P < 0.001). However, co-administration of dihydrolipoic acid (DHLA) prevented Compound 1-mediated cell death when incubated with the compound and also after 1 h of Compound 1 alone. Pre-treatment with GSH, then removal of the antioxidant resulted in abolition of Compound 1 toxicity (vehicle control, 63.6 ± 16.7 versus Compound 1 alone 26.1 ± 13.6% versus GSH pre-treatment, 65.7 ± 7.3%). In a cell-free incubation, NMR analysis revealed that GSH does not react with Compound 1, indicating that this agent is not likely to directly deplete membrane thiols. Compound 1's MNL toxicity is more likely to be linked with changes in cell membrane conformation, which may induce consequent thiol depletion that is reversible by exogenous thiols. © 2004 Elsevier B.V. All rights reserved.

Correlates of spontaneous reporting of adverse drug reactions within primary care: the paradox of low prescribers who are high reporters

AIM(S) To examine Primary Care Trust (PCT) demographics influencing general practitioner (GP) involvement in pharmacovigilance. METHODS PCT adverse drug reaction (ADR) reports to the Yellow Card scheme between April 2004 and March 2006 were obtained for the UK West Midlands region. Reports were analysed by all drugs, and most commonly reported drugs (‘top drugs’). PCT data, adjusted for population size, were aggregated. Prescribing statistics and other characteristics were obtained for each PCT, and associations between these characteristics and ADR reporting rates were examined. RESULTS During 2004–06, 1175 reports were received from PCTs. Two hundred and eighty (24%) of these reports were for 14 ‘top drugs’. The mean rate of reporting for PCTs was 213 reports per million population. A total of 153 million items were prescribed during 2004–06, of which 33% were ‘top drugs’. Reports for all drugs and ‘top drugs’ were inversely correlated with the number of prescriptions issued per thousand population (rs = -0.413, 95% CI -0.673, -0.062, P < 0.05, and r = -0.420, 95% CI -0.678, -0.071, P < 0.05, respectively). Reporting was significantly negatively correlated with the percentages of male GPs within a PCT, GPs over 55 years of age, single-handed GPs within a PCT, the average list size of a GP within a PCT, the overall deprivation scores and average QOF total points. ADR reports did not correlate significantly with the proportion of the population over 65 years old. CONCLUSIONS Some PCT characteristics appear to be associated with low levels of ADR reporting. The association of low prescribing areas with high ADR reporting rates replicates previous findings.

Use of a solvent-free dry matrix coating for quantitative matrix-assisted laser desorption ionization imaging of 4-bromophenyl-1,4-diazabicyclo(3.2.2)nonane-4-carboxylate in rat brain and quantitative analysis of the drug from laser microdissected tissue regions

A dry matrix application for matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) was used to profile the distribution of 4-bromophenyl-1,4-diazabicyclo(3.2.2)nonane-4-carboxylate, monohydrochloride (BDNC, SSR180711) in rat brain tissue sections. Matrix application involved applying layers of finely ground dry alpha-cyano-4-hydroxycinnamic acid (CHCA) to the surface of tissue sections thaw mounted onto MALDI targets. It was not possible to detect the drug when applying matrix in a standard aqueous-organic solvent solution. The drug was detected at higher concentrations in specific regions of the brain, particularly the white matter of the cerebellum. Pseudomultiple reaction monitoring imaging was used to validate that the observed distribution was the target compound. The semiquantitative data obtained from signal intensities in the imaging was confirmed by laser microdissection of specific regions of the brain directed by the imaging, followed by hydrophilic interaction chromatography in combination with a quantitative high-resolution mass spectrometry method. This study illustrates that a dry matrix coating is a valuable and complementary matrix application method for analysis of small polar drugs and metabolites that can be used for semiquantitative analysis.

Solubility enhancement of poorly water soluble drugs using liposome technology

The aim of this work is to investigate the various parameters that could control the encapsulation of lipophilic drugs and investigate the influence of the physical properties of poorly water-soluble drugs on bilayer loading. Initial work investigated on the solubilisation of ibuprofen, a model insoluble drug. Drug loading was assessed using HPLC and UV spectrophotometric analysis. Preliminary studies focused on the influence of bilayer composition on drug loading to obtain an optimum cholesterol concentration. This was followed up by studies investigating the effect of longer alkyl chain lipids, unsaturated alkyl chain lipids and charged lipids. The studies also focused on the effects of pH of the hydration medium and addition of the single chain surfactant a-tocopherol. The work was followed up by investigation of a range of insoluble drugs including flurbiprofen, indomethacin, sulindac, mefenamic acid, lignocaine and progesterone to investigate the influence of drugs properties and functional group on liposomal loading. The results show that no defined trend could be obtained linking the drug loading to the different drug properties including molecular weight, log P and other drug specific characteristics. However, the presence of the oppositely charged lipids improved the encapsulation of all the drugs investigated with a similar effect obtained with the substitution of the longer chain lipids. The addition of the single chain surfactant a-tocopherol resulted in enhancement of drug loading and possibly is governed by the log P of the drug candidate. Environmental scanning-electron microscopy (ESEM) was used to dynamically follow the changes in liposome morphology in real time during dehydration thereby providing a alternative assay of liposome formulation and stability. The ESEM analysis clearly demonstrated ibuprofen incorporation enhanced the stability of PC:Chol liposomes.

The stability and formulation of topical analgesics

High-performance liquid chromatographic methods are developed for the simultaneous determination of various salicylates, their p-hydroxy isomers and nicotinic acid esters. The method is sensitive enough to detect trace amounts (~µM/L)of the product generated from cross reactivity between the drugs and the vehicle. The developed method also allows analysis of various topical products containing salicylate and nicotinate esters in their formulations. Applying this method, the degradation profiles of salicylates, nicotinates, p-hydroxy benzoate, o-methoxy benzoate and aspirin prodrugs in alkaline media are determined. The profile for alkyl salicylate degradation is found to be first order (A---? B) When the alcoholic radical is similar to that of the ester. In alcohol having a radical different from that of the ester function, the degradation is found to proceed through competitive transesterification and hydrolysis. The intermediates are identified following synthesis and isolation. The rate and extent of transesterification depends on the proportion of alcohol present in the system. Equations are presented to model the time profiles of reactant and product concentration. The reactions are base catalysed and the predominant pathway involves a concerted solvent attack upon the salicylate anion. Competitive hydrolysis of both ester components also follows this mechanism at moderate pH values but rates increase under strongly alkaline conditions as direct hydroxide attack becomes significant. In contrast, transesterification is independent of base concentration once full ionization is accomplished. The competitive hydrolysis is modelled using equations involving the dielectric constant of the medium. A range of other esters are also shown to undergo base-catalysed transesterification. In non-alcoholic solution phenyl salicylate undergoes a concentration-dependent oligomerisation which yields salsalate among the products. Competitive transesterification and hydrolysis also occur in products for topical use which have vehicles based upon alcohol, glycol or glycol polymers. Such reactions may compromise stability assessments, pharmaceutical integrity and delivery profiles.

Patients' perceptions and experiences of taking oral glucose-lowering agents: a longitudinal qualitative study

Aims The aims of this study were to examine Type 2 diabetic patients' expectations, perceptions and experiences of oral glucose-lowering agents (OGLAs), including their reasons for taking/not taking these drugs as prescribed and to provide recommendations for developing interventions to improve OGLA adherence. Methods Longitudinal, qualitative study using repeat in-depth interviews with patients (n = 20) over 4 years following clinical diagnosis. Respondents were recruited from primary and secondary care settings across Lothian, Scotland, UK. Results Despite experiences of side-effects, dislikes and concerns about taking multiple drugs and a belief that OGLAs could themselves cause one's diabetes to progress, most respondents appeared motivated to take these drugs as prescribed. This motivation seemed to arise from respondents' experiences of taking OGLAs and observing them to 'work'. Some respondents described feeling better after taking OGLAs, others, typically those who were asymptomatic, used blood glucose self-monitoring and/or glycated haemoglobin results to observe and evidence the effects of their OGLAs. Most respondents demonstrated a 'passive' expectation that health professionals should be responsible for decisions about medications. Hence, non-adherence typically resulted from forgetfulness rather than ambivalence about either medication or consultation style. Respondent concern about OGLA's largely centred upon lack of knowledge about the medication and what to do when doses were missed. Conclusion The findings call for multifaceted strategies to promote adherence. These could include education to address misconceptions and advise patients how to respond to missed doses; reminders to help patients remember to take their drugs; and structured feedback on the impact of OGLAs on glycaemic control.

Quality control of pharmaceutical ingredients:developing a caking test for industry

Objectives - Powdered and granulated particulate materials make up most of the ingredients of pharmaceuticals and are often at risk of undergoing unwanted agglomeration, or caking, during transport or storage. This is particularly acute when bulk powders are exposed to extreme swings in temperature and relative humidity, which is now common as drugs are produced and administered in increasingly hostile climates and are stored for longer periods of time prior to use. This study explores the possibility of using a uniaxial unconfined compression test to compare the strength of caked agglomerates exposed to different temperatures and relative humidities. This is part of a longer-term study to construct a protocol to predict the caking tendency of a new bulk material from individual particle properties. The main challenge is to develop techniques that provide repeatable results yet are presented simply enough to be useful to a wide range of industries. Methods - Powdered sucrose, a major pharmaceutical ingredient, was poured into a split die and exposed to high and low relative humidity cycles at room temperature. The typical ranges were 20–30% for the lower value and 70–80% for the higher value. The outer die casing was then removed and the resultant agglomerate was subjected to an unconfined compression test using a plunger fitted to a Zwick compression tester. The force against displacement was logged so that the dynamics of failure as well as the failure load of the sample could be recorded. The experimental matrix included varying the number of cycles, the amount between the maximum and minimum relative humidity, the height and diameters of the samples, the number of cycles and the particle size. Results - Trends showed that the tensile strength of the agglomerates increased with the number of cycles and also with the more extreme swings in relative humidity. This agrees with previous work on alternative methods of measuring the tensile strength of sugar agglomerates formed from humidity cycling (Leaper et al 2003). Conclusions - The results show that at the very least the uniaxial tester is a good comparative tester to examine the caking tendency of powdered materials, with a simple arrangement and operation that are compatible with the requirements of industry. However, further work is required to continue to optimize the height/ diameter ratio during tests.

A comparative study of cationic liposome and niosome-based adjuvant systems for protein subunit vaccines:characterisation, environmental scanning electron microscopy and immunisation studies in mice

Vesicular adjuvant systems composing dimethyldioctadecylammonium (DDA) can promote both cell-mediated and humoral immune responses to the tuberculosis vaccine fusion protein in mice. However, these DDA preparations were found to be physically unstable, forming aggregates under ambient storage conditions. Therefore there is a need to improve the stability of such systems without undermining their potent adjuvanticity. To this end, the effect of incorporating non-ionic surfactants, such as 1-monopalmitoyl glycerol (MP), in addition to cholesterol (Chol) and trehalose 6,6′-dibehenate (TDB), on the stability and efficacy of these vaccine delivery systems was investigated. Differential scanning calorimetry revealed a reduction in the phase transition temperature (T c) of DDA-based vesicles by ∼12°C when MP and cholesterol (1:1 molar ratio) were incorporated into the DDA system. Transmission electron microscopy (TEM) revealed the addition of MP to DDA vesicles resulted in the formation of multi-lamellar vesicles. Environmental scanning electron microscopy (ESEM) of MP-Chol-DDA-TDB (16:16:4:0.5 μmol) indicated that incorporation of antigen led to increased stability of the vesicles, perhaps as a result of the antigen embedding within the vesicle bilayers. At 4°C DDA liposomes showed significant vesicle aggregation after 28 days, although addition of MP-Chol or TDB was shown to inhibit this instability. Alternatively, at 25°C only the MP-based systems retained their original size. The presence of MP within the vesicle formulation was also shown to promote a sustained release of antigen in-vitro. The adjuvant activity of various systems was tested in mice against three subunit antigens, including mycobacterial fusion protein Ag85b-ESAT-6, and two malarial antigens (Merozoite surface protein 1, MSP1, and the glutamate rich protein, GLURP). The MP- and DDA-based systems induced antibody responses at comparable levels whereas the DDA-based systems induced more powerful cell-mediated immune responses. © 2006 The Authors.