Triazole derivatives as potential xanthine oxidase inhibitors: Design, enzyme inhibition potential, and docking studies

Considerable ingenuity has been shown in the recent years in the discovery of novel xanthine oxidase (XO) inhibitors that fall outside the purine scaffold. The triazole nucleus has been the cornerstone for the development of many enzyme inhibitors for the clinical management of several diseases, where hyperuricemia is one of them. Here, we give a critical overview of significant research on triazole-based XO inhibitors, with respect to their design, synthesis, inhibition potential, toxicity, and docking studies, done till now. Based on these literature findings, we can expect a burst of modifications on triazole-based scaffolds in the near future by targeting XO, which will treat hyperuricemics, that is, painful conditions like gout that at present are hard to deal with.

Shikonin derivatives as potent xanthine oxidase inhibitors: in-vitro study

Induction of hypersensitivity reactions (may be fatal too) by specific XO inhibitors has led to development of new molecules that are efficacious and have safer ADME profile. Among natural compounds, biologically active Alkannin/Shikonin (A/S) derivatives have unexplored XO inhibition potential. Therefore, their iso-hexenylnaphthazarin nucleus was studied and found that the nucleus is similar to that of allopurinol, signifying the XO inhibitory potential of these derivatives. For confirmation of their potential, β,β-dimethylacrylshikonin and deoxyshikonin were successfully isolated and characterised from Arnebia euchroma (Royle.) Johnst. (Boraginaceae) and were evaluated for in vitro XO inhibitory potential. β,β-dimethylacrylshikonin and deoxyshikonin showed a good XO inhibition potential with IC₅₀ values of 7.475 ± 1.46 µg/mL and 4.487 ± 0.88 µg/mL, respectively. Results also validated the pharmacophore hypothesis, and it was concluded that nucleus iso-hexenylnaphthazarin can be remodelled for optimising the efficacy.

Dihydrofolate reductase inhibitors: patent landscape and phases of clinical development (2001-2021)

INTRODUCTION

Dihydrofolate reductase (DHFR) plays an important role in the biosynthesis of amino acid and folic acid. It participates by reducing dihydrofolate to tetrahydrofolate, in the presence of nicotinamide dinucleotide phosphate cofactor, and has been verified by various clinical studies to use DHFR as a target for the treatment of cancer and various bacterial infections.

AREA COVERED

In this review, we have disclosed patents of synthetics and natural DHFR inhibitors with diaminopyrimidine and quinazoline nucleus from 2001. Additionally, this review highlights the clinical progression of numerous DHFR inhibitors received from the last five years.

EXPERT OPINION

From 2001 to 2021, numerous active chemical scaffolds have been introduced and are exposed as lead candidates that have entered clinical trials as potent DHFR inhibitors. Moreover, researchers have paid considerable attention to the development of a new class of DHFR inhibitors with higher selectivity and potency. This development includes synthesis of synthetic as well as natural compounds that are potent DHFR inhibitors. On the basis of literature review, we can anticipate that there are a huge number of novel active molecules available for the future that could possess superior abilities to target this enzyme with a profound pharmacological profile.

Design, synthesis, and biological evaluation of isatin-indole-3-carboxaldehyde hybrids as a new class of xanthine oxidase inhibitors

A novel series of triazole-linked isatin-indole-3-carboxaldehyde hybrids based on the febuxostat skeleton and its binding site interactions were rationally designed and synthesized as potential xanthine oxidase inhibitors. Among the synthesized hybrids, A19 showed the most potent xanthine oxidase inhibition (IC₅₀  = 0.37 µM) with the mixed-type inhibitory scenario. Structure-activity relationship studies revealed that methoxy (OCH₃ ) substitution on position 5 of the isatin nucleus and a two-carbon distance between isatin and the triazole moiety is most tolerable for the inhibitory potential. Various binding interactions of A19 with the binding site of xanthine oxidase are also streamlined by molecular docking studies, which showcase the favorable binding pattern for xanthine oxidase inhibition by the hybrid. Furthermore, molecular dynamic studies were performed that suggest the stability of the enzyme-hybrid complex. Overall, the study suggests that hybrid A19 can act as an effective hit lead for further development of potent xanthine oxidase inhibitors.

Donepezil-Inspired Multitargeting Indanone Derivatives as Effective Anti-Alzheimer's Agents

In continuous efforts to develop anti-Alzheimer's agents, we rationally designed and synthesized a series of multitargeting molecules by incorporating the essential molecular features of the standard drug donepezil. Among the series, compound 4b showed multitargeting properties to act as an anti-Alzheimer's agent, which is better tolerable in vivo than donepezil. Acetylcholinesterase (AChE) inhibition data showed that compound 4b inhibits the enzyme with a half-maximal inhibitory concentration (IC₅₀) value of 0.78 μM and also showed DNA protection, which was confirmed through the DNA nicking assay, suggesting the protective effect of 4b against oxidative DNA damage. Compound 4b also showed 53.04% inhibition against Aβ_1-42 aggregations, which was found comparable to that of the standard compound curcumin. Molecular dynamics simulations were performed to check the stability of compound 4b with the enzyme AChE, which showed that the enzyme-ligand complex is stable enough to block the hydrolysis of acetylcholine in the brain. Its higher LD₅₀ cutoff value (50 mg/kg) in comparison to donepezil (LD₅₀: 25 mg/kg) made it safer, suggesting that it can be used in further clinical experiments. To evaluate its anti-Alzheimer property, a mice model with melamine-induced cognitive dysfunction was used, and Morris water maze and Rotarod tests were performed. A significant improvement in memory was observed after the treatment with compound 4b and donepezil. The study postulated that the introduction of important structural features of donepezil (dimethoxyindanone moiety as ring-A) embarked with terminal aromatic ether (ring-B and ring-C) made 4b a multitargeting molecule that offers a way for developing alternative therapeutics in the future against Alzheimer's disease (AD).

Discovery of potent inhibitors for Mpro enzyme of SARS-COV2 by multi-stage in-silico screening of Alkannin/shikonin

Novel coronavirus disease, a serious challenge for the healthcare system, has diverted all the researchers toward the exploration of potential targets, compounds or vaccines for the management of this disease. M^pro enzyme was found to be crucial for replication of this virus which makes this enzyme an attractive drug target for SARS-CoV-2. Diverse pharmacological profile of Alkannin/shikonin (A/S) derivatives build up curiosity to study their antiviral profile. Therefore, current study utilises various computational tools to screen and evaluate all the discovered A/S derivatives to inhibit the M^pro enzyme for its anti-viral activity. Results revealed that the A/S has a very good tendency to inhibit the catalytic activity of the enzyme. Moreover, (5 R,6R)-5,8-dihydroxy-6-methoxy-3,4,5,6-tetrahydro-2H-benzo[a]anthracene-1, 7, 12-trione, an A/S derivative was found to possess drug-likeliness properties and a good ADME profile. Moreover, its complex with Mpro enzyme was found stable for 50 ns which makes it a very promising ligand to treat COVID-19.

Design, Synthesis, biological investigations and molecular interactions of triazole linked tacrine glycoconjugates as Acetylcholinesterase inhibitors with reduced hepatotoxicity

Tacrine is a known Acetylcholinesterase (AChE) inhibitors having hepatotoxicity as main liability associated with it. The present study aims to reduce its hepatotoxicity by synthesizing tacrine linked triazole glycoconjugates via Huisgen's [3 + 2] cycloaddition of anomeric azides and terminal acetylenes derived from tacrine. A series of triazole based glycoconjugates containing both acetylated (A-1 to A-7) and free sugar hydroxyl groups (A-8 to A-14) at the amino position of tacrine were synthesized in good yield taking aid from molecular docking studies and evaluated for their in vitro AChE inhibition activity as well as hepatotoxicity. All the hybrids were found to be non-toxic on HePG2 cell line at 200 μM (100 % cell viability) as compared to tacrine (35 % cell viability) after 24 h of incubation period. Enzyme kinetic studies carried out for one of the potent hybrids in the series A-1 (IC₅₀ 0.4 μM) revealed its mixed inhibition approach. Thus, compound A-1 can be used as principle template to further explore the mechanism of action of different targets involved in Alzheimer's disease (AD) which stands as an adequate chemical probe to be launched in an AD drug discovery program.

Phytoconstituents from ten natural herbs as potent inhibitors of main protease enzyme of SARS-COV-2: In silico study

BACKGROUND

Lack of treatment of novel Coronavirus disease led to the search of specific antivirals that are capable to inhibit the replication of the virus. The plant kingdom has demonstrated to be an important source of new molecules with antiviral potential.

PURPOSE

The present study aims to utilize various computational tools to identify the most eligible drug candidate that have capabilities to halt the replication of SARS-COV-2 virus by inhibiting Main protease (Mpro) enzyme.

METHODS

We have selected plants whose extracts have inhibitory potential against previously discovered coronaviruses. Their phytoconstituents were surveyed and a library of 100 molecules was prepared. Then, computational tools such as molecular docking, ADMET and molecular dynamic simulations were utilized to screen the compounds and evaluate them against Mpro enzyme.

RESULTS

All the phytoconstituents showed good binding affinities towards Mpro enzyme. Among them laurolitsine possesses the highest binding affinity i.e. -294.1533 kcal/mol. On ADMET analysis of best three ligands were simulated for 1.2 ns, then the stable ligand among them was further simulated for 20 ns. Results revealed that no conformational changes were observed in the laurolitsine w.r.t. protein residues and low RMSD value suggested that the Laurolitsine-protein complex was stable for 20 ns.

CONCLUSION

Laurolitsine, an active constituent of roots of Lindera aggregata, was found to be having good ADMET profile and have capabilities to halt the activity of the enzyme. Therefore, this makes laurolitsine a good drug candidate for the treatment of COVID-19.

Phytoconstituents from ten natural herbs as potent inhibitors of main protease enzyme of SARS-COV-2: In silico study

BACKGROUND

Lack of treatment of novel Coronavirus disease led to the search of specific antivirals that are capable to inhibit the replication of the virus. The plant kingdom has demonstrated to be an important source of new molecules with antiviral potential.

PURPOSE

The present study aims to utilize various computational tools to identify the most eligible drug candidate that have capabilities to halt the replication of SARS-COV-2 virus by inhibiting Main protease (Mpro) enzyme.

METHODS

We have selected plants whose extracts have inhibitory potential against previously discovered coronaviruses. Their phytoconstituents were surveyed and a library of 100 molecules was prepared. Then, computational tools such as molecular docking, ADMET and molecular dynamic simulations were utilized to screen the compounds and evaluate them against Mpro enzyme.

RESULTS

All the phytoconstituents showed good binding affinities towards Mpro enzyme. Among them laurolitsine possesses the highest binding affinity i.e. -294.1533 kcal/mol. On ADMET analysis of best three ligands were simulated for 1.2 ns, then the stable ligand among them was further simulated for 20 ns. Results revealed that no conformational changes were observed in the laurolitsine w.r.t. protein residues and low RMSD value suggested that the Laurolitsine-protein complex was stable for 20 ns.

CONCLUSION

Laurolitsine, an active constituent of roots of Lindera aggregata, was found to be having good ADMET profile and have capabilities to halt the activity of the enzyme. Therefore, this makes laurolitsine a good drug candidate for the treatment of COVID-19.

Rational approaches for the design of various GABA modulators and their clinical progression

GABA (γ-amino butyric acid) is an important inhibitory neurotransmitter in the central nervous system. Attenuation of GABAergic neurotransmission plays an important role in the etiology of several neurological disorders including epilepsy, Alzheimer's disease, Huntington's chorea, migraine, Parkinson's disease, neuropathic pain, and depression. Increase in the GABAergic activity may be achieved through direct agonism at the GABAA receptors, inhibition of enzymatic breakdown of GABA, or by inhibition of the GABA transport proteins (GATs). These functionalities make GABA receptor modulators and GATs attractive drug targets in brain disorders associated with decreased GABA activity. There have been several reports of development of GABA modulators (GABA receptors, GABA transporters, and GABAergic enzyme inhibitors) in the past decade. Therefore, the focus of the present review is to provide an overview on various design strategies and synthetic approaches toward developing GABA modulators. Furthermore, mechanistic insights, structure-activity relationships, and molecular modeling inputs for the biologically active derivatives have also been discussed. Summary of the advances made over the past few years in the clinical translation and development of GABA receptor modulators is also provided. This compilation will be of great interest to the researchers working in the field of neuroscience. From the light of detailed literature, it can be concluded that numerous molecules have displayed significant results and their promising potential, clearly placing them ahead as potential future drug candidates.

Most recent strategies targeting estrogen receptor alpha for the treatment of breast cancer

Breast cancer is the most prominent, frequently diagnosed and leading cause of death among women. Estrogen is an agonist of estrogen receptor alpha (ER-α), expressed in mammary glands and is responsible for initiating many signalling pathways that lead to differentiation and development of breast tissue. Any mutations in these signalling pathways result in irregular growth of mammary tissue, leading to the development of tumour or cancer. All these observations attract the attention of researchers to antagonize ER-α receptor either by developing selective estrogen receptor modulators or by selective estrogen receptor degraders. Therefore, this article provides a brief overview of various factors that are responsible for provoking breast cancer in women and design strategies recently used by the various research groups across the world for antagonizing or demodulating ER-α.

Rational approaches, design strategies, structure activity relationship and mechanistic insights for therapeutic coumarin hybrids

Hybrid molecules, furnished by combining two or more pharmacophores is an emerging concept in the field of medicinal chemistry and drug discovery that has attracted substantial traction in the past few years. Naturally occurring scaffolds such as coumarins display a wide spectrum of pharmacological activities including anticancer, antibiotic, antidiabetic and others, by acting on multiple targets. In this view, various coumarin-based hybrids possessing diverse medicinal attributes were synthesized in the last five years by conjugating coumarin moiety with other therapeutic pharmacophores. The current review summarizes the recent development (2014 and onwards) of these pharmacologically active coumarin hybrids and demonstrates rationale behind their design, structure-activity relationships (SAR) and mechanistic studies performed on these hybrid molecules. This review will be beneficial for medicinal chemist and chemical biologist, and in general to the drug discovery community and will facilitate the synthesis and development of novel, potent coumarin hybrid molecules serving as lead molecules for the treatment of complex disorders.

Monocarbonyl Curcumin-Based Molecular Hybrids as Potent Antibacterial Agents

Keeping in view various pharmacological attributes of curcumin, coumarin, and isatin derivatives, triazole-tethered monocarbonyl curcumin-coumarin and curcumin-isatin molecular hybrids have been synthesized and evaluated for their antibacterial potential against Gram-positive (Enterococcus faecalis and Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa and Escherichia coli) human pathogenic bacterial strains. Among all hybrid molecules, A-4 and B-38 showed the most potent antibacterial activity with inhibition zones of 29 and 31 mm along with MIC values of 12.50 and 6.25 μg/mL, respectively. Structure-activity relationship that emerged from biological data revealed that the two-carbon alkyl chain between triazole and coumarin/isatin moiety is well tolerable for the activity. Bromo substitution at the fifth position of isatin, para-cholo substitution in the case of curcumin-isatin, and para-methoxy in the case of curcumin-coumarin hybrids on ring A of curcumin are most suitable groups for the antibacterial activity. Various types of binding interactions of A-4 and B-38 within the active site of dihydrofolate reductase (DHFR) of S. aureus are also streamlined by molecular modeling studies, suggesting their capability in completely blocking DHFR.

Design, Synthesis, Antimicrobial Evaluation, and Molecular Modeling Studies of Novel Indolinedione-Coumarin Molecular Hybrids

Keeping in view various pharmacological attributes of indole and coumarin derivatives, a new series of indolindione-coumarin molecular hybrids was rationally designed and synthesized. All synthesized hybrid molecules were evaluated for their antimicrobial potential against Gram-negative bacterial strains (Escherichia coli and Salmonella enterica), Gram-positive bacterial strains (Staphylococcus aureus and Mycobacterium smegmatis), and four fungal strains (Candida albicans, Alternaria mali, Penicillium sp., and Fusarium oxysporum) by using the agar gel diffusion method. Among all synthetics, compounds K-1 and K-2 were found to be the best antimicrobial agents with the minimum inhibitory concentration values of 30 and 312 μg/mL, against Penicillium sp. and S. aureus, respectively. The biological data revealed some interesting facts about the structure-activity relationship which state that the electronic environment on the indolinedione moiety and carbon chain length between indolinedione and triazole moieties considerably affect the antimicrobial potential of the synthesized hybrids. Various types of binding interactions of K-2 within the active site of S. aureus dihydrofolate reductase were also streamlined by molecular modeling studies, which revealed the possible mechanism for potent antibacterial activity of the compound.

5,6-Benzoflavones as cholesterol esterase inhibitors: synthesis, biological evaluation and docking studies

In a continued effort to develop potent cholesterol esterase (CEase) inhibitors, a series of 5,6-benzoflavone derivatives was rationally designed and synthesized by changing the position of the benzene ring attached to the flavone skeleton in previously reported 7,8-benzoflavones. All the synthesized compounds were checked for their inhibitory potential against cholesterol esterase (CEase) using a spectrophotometric assay. Among the series of forty compounds, seven derivatives (B-10 to B-16) exhibited above 90 percent inhibition against CEase in an in vitro enzymatic assay. Compound B-16 showed the most promising activity with an IC50 value of 0.73 nM against cholesterol esterase. To determine the type of inhibition, enzyme kinetic studies were carried out for B-16, which revealed its mixed-type inhibition approach. Moreover, to figure out the key binding interactions of B-16 with the amino acid residues of the enzyme's active site, molecular protein-ligand docking studies were also performed. B-16 completely blocks the catalytic assembly of CEase and prevents it from participating in the ester hydrolysis mechanism. The favorable binding conformation of B-16 suggests its prevailing role as a CEase inhibitor. Overall, the study showed that the cis-orientation of ring A with respect to the carbonyl group of ring C is responsible for the potent CEase inhibitory activity of the newly synthesized compounds.

A phase I dose escalation pharmacokinetic (PK) and pharmacodynamic (PD) study of weekly and twice weekly erlotinib in advanced stage solid malignancies

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Background: Erlotinib is a potent oral TKI of the epidermal growth factor receptor (EGFR). At the current recommended daily dose of 150 mg/day there is activity in advanced stage NSCLC, but with frequent grade 1/2 rash and diarrhea. We performed a phase I dose escalation study of erlotinib with a once and twice weekly schedule to assess the PKs, PDs, and to determine if toxicities would be less on an intermittent but high dose schedule. Methods: A standard dose escalation schedule starting at 1,400 mg once/week and 600 mg twice/week with increments of 200 mg to 4 dose cohorts/schedule was utilized with three patients per cohort. A cycle consisted of 3 weeks of therapy. PKs were performed on cycle 1 and 2. PDs on normal skin punch biopsies were performed at baseline and after cycle 1. Tumour evaluation was done following every 2nd cycle. Subjects were treated until progression or unacceptable toxicity. Results: 32 patients were enrolled from Oct 2004-April 2006. Median age 58 years (28–74 years); median PS 1 (0–2); and median prior palliative systemic regimens 2 (0–6). In the once weekly schedule the maximum tolerated dose (MTD) was not reached with the top dose of 2,000 mg/week. A median of 2 cycles were delivered (1–14), with 3/13 patients achieving stable disease = 3 months. 4/13 patients had G1 rash and 6/13 patients G1 diarrhea during the first 2 cycles. In the twice weekly schedule the MTD was reached at 1,200 mg twice/week with 2/6 subjects experiencing G3 rash. The recommended dose level is 1,000 mg twice/week. A median of 4 cycles were delivered (1–28) with 2 partial responses, 1 minor response and 6 stable disease = 3 months out of 19 patients in total. G1/2 rash or diarrhea occurred in 13 and 9 patients respectively. No corneal toxicity was seen. The PK data demonstrated a variable but linear pattern. At 1,000 mg twice/week the median Cmax, Tmax and AUC0–24 hr was 6.28 μg/ml, 2 hours and 135 μg.h/ml respectively. PD analysis is ongoing. Conclusions: A once weekly and twice weekly high dose schedule of erlotinib is feasible, with MTD not reached in the once weekly schedule. A recommended dose of 1,000 mg twice/week has clinical activity, is generally well tolerated, and results in significantly higher systemic exposure than the 150 mg once daily dose.

No significant financial relationships to disclose.

Carboplatin and paclitaxel for advanced and recurrent cervical carcinoma: the British Columbia Cancer Agency experience

BACKGROUND

One of the most active chemotherapy combinations in advanced or recurrent cervical cancer is cisplatin-paclitaxel. However, this palliative regimen is associated with significant toxicity. Carboplatin-paclitaxel is thus an attractive option.

METHODS

Patients with advanced or recurrent carcinoma of the cervix treated with carboplatin-paclitaxel from April 2000 were included in the study. Starting doses of carboplatin-paclitaxel were: AUC 5-6 and 155-175 mg/m(2), respectively, repeated every 28 days.

RESULTS

Twenty-five women treated with this combination were identified. Twenty-three women (92%) had prior treatment with pelvic radiotherapy and 14 (56%) had had concurrent radio-sensitizing cisplatin. There was a 20% PR and a 20% CR rate (10/25). The median progression-free survival for the entire group was 3 months. Responders had a median PFS of 16 months. Fourteen patients (56%) had died of disease progression. The median overall survival (OS) was 21 months. Common toxicities included: grade 1 or 2 anemia, 68%; grade 3 or 4 anemia, 32%; grade 3 or 4 neutropenia, 32%; and grade 1 or 2 peripheral neuropathy, 24%. ECOG PS did not change significantly while on treatment. Eighty-four percent of treatments were delivered on time, and 96% at full dose.

CONCLUSIONS

Carboplatin-paclitaxel is an active combination in advanced and recurrent cervical cancer. In this predominantly pre-irradiated group, the combination was deliverable, well tolerated, and the most commonly observed toxicity was anemia.

Effects of non-steroidal anti-inflammatory drugs on hypertension control using angiotensin converting enzyme inhibitors and thiazide diuretics

OBJECTIVES

To determine the impact of three non-steroidal anti-inflammatory drugs on the efficacy of two anti-hypertensive drugs.

DESIGN

Fifteen women with arthritis and hypertension who were receiving lisinopril and HCT, and administered sequentially in random order ibuprofen, sulindac, and diclofenac for one month each, with an intervening two-week washout period between each treatment period. During the washout period, subjects received paracetamol.

SETTING

Hypertension Clinic, Medical Centre, Harare, Zimbabwe.

SUBJECTS

Fifteen female hypertensive women with documented arthritis.

MAIN OUTCOME MEASURES

Blood pressure at the end of two weeks of paracetamol was compared with blood pressure after one month of treatment with each of the NSAID.

RESULTS

Mean blood pressure was unchanged before and after all NSAIDs: 108 +/- 7 versus 107 +/- 9 for diclofenac, 108 +/- 9 versus 108 +/- 9 for sulindac, and 108 +/- 8 versus 107 +/- 9 for ibuprofen. The 24 hour urinary sodium excretion was not significantly different.

CONCLUSION

The three NSAIDs investigated did not neutralise the antihypertensive effect of the combination of lisinopril and HCT, and hence the blood pressure lowering action of the combination may not be prostaglandin dependent.

General practitioners and clinical guidelines

OBJECTIVE

To assess the attitudes of general practitioners in Harare, Zimbabwe, towards the use of clinical practice guidelines (CPG's).

DESIGN

Cross sectional survey.

SETTING

General practitioners in private practice within the urban Harare (Zimbabwe) environs.

SUBJECTS

Two hundred and thirty two general practitioners in Harare, Zimbabwe.

MAIN OUTCOME MEASURES

The response to a questionnaire enlisting attitudes to CPGs.

RESULTS

Questionnaires were sent to 232 general practitioners. Of these, 137 (59.1%) returned a completed questionnaire. Among the respondents, 95.6% felt that general practitioners should be involved in the development of guidelines, 72.6% had read at least one guideline, 65.9% were prepared to use guidelines in their practice, 61.6% thought that guidelines would improve their treatment ability, and 59.7% thought that guidelines would improve their knowledge of disease. 76.5% felt that the government should not legislate, 66.2% felt that guidelines reduce practitioners' flexibility and 57.9% felt that guidelines would not improve their diagnostic ability.

CONCLUSION

The respondents were, in general, favourably disposed towards CPGs. Most had already read some guidelines, and about two thirds were prepared to use them. Almost all respondents felt that general practitioners should be involved in the development of guidelines for use in general practice. These general practitioners felt that guidelines were likely to help them treat patients than to make a diagnosis. Despite these favourable attitudes, many practitioners felt that guidelines would limit their personal flexibility in caring for patients. Organisations developing or implementing CPGs in general practice should address these concerns.

Compliance with medication in patients with heart failure in Zimbabwe

OBJECTIVES

To determine the extent of adherence to prescribed medication in patients with chronic heart failure and to determine to what extent patients recall information given regarding their medication.

DESIGN

Compliance and knowledge of prescribed medication was studied in 22 heart failure patients [mean age 45 +/- 4 (range 40-67); 14 (64%) male], using in-depth interviews performed 30 days after having been prescribed medication. All patients received standardised verbal and written information regarding their medication.

SETTING

Patients attending four general practices in the private sector (in Harare, Zimbabwe) for at least six months prior to enrolling were in included in the study.

RESULTS

Only 12 (55%) patients could correctly name what medication had been prescribed, 11 (50%) were unable to state the prescribed doses and 14 (64%) could not account for when the medication was to be taken, that is to say, at what time of day and when in relation to meals the medication was to be taken. In the overall assessment six (27%) patients were found non-compliant and 16 (73%) patients were considered as possibly being compliant with their prescribed medication.

CONCLUSIONS

Non-compliance was common in heart failure patients, as were shortcomings in patients' knowledge regarding prescribed medication, despite efforts to give adequate information. There exists a need for alternative strategies to improve compliance in these patients.

Neuropathic pain--from mice to men

The past decade has seen great progress in understanding the syndrome of neuropathic pain, its causes and in finding new drugs that promise great benefit. For example, an early outcome of the research has been the observation that the new drugs do not blunt normal pain sensation--a pattern beginning to find explanation through the realisation that neural pain circuits rewire themselves, both anatomically and biochemically, after nerve injury. In this article, we discuss a case of a known diabetic patient with intractable pain and the course of management provided by the use of novel tools and devices coming to the fore in this rapidly expanding specialty.

Use of a simple pain model to evaluate analgesic activity of ibuprofen versus paracetamol

OBJECTIVE

To evaluate the analgesic activity of ibuprofen against paracetamol using a simple pain model.

DESIGN

A double-blind study.

SETTING

Twenty general practitioners in Harare, Zimbabwe.

PATIENTS

Adults with acute sore throat of a maximum of two days' duration.

INTERVENTIONS

One hundred and thirteen patients with acute pain associated with tonsillo-pharyngitis randomly received either 400 mg ibuprofen or 1000 mg paracetamol. The study design included repeated administration up to 48 hours to assess tolerability.

MAIN OUTCOME MEASURES

At hourly intervals for six hours after the first dose of treatment, the patients evaluated pain intensity on swallowing, difficulty in swallowing and global pain relief according to visual analogue scales.

RESULTS

Ibuprofen 400 mg was significantly more effective than paracetamol 1000 mg in all three ratings, at all time-points for pain intensity and difficulty in swallowing, and from two hours onwards for pain relief. There were no serious adverse effects and no statistically significant difference in the incidence of adverse effects in the two treatment groups.

CONCLUSIONS

Sore throat pain provided a sensitive model to assess the analgesic efficacy of class I analgesics and discriminated between the analgesic efficacy of ibuprofen and paracetamol.

Acute systemic inflammation impairs endothelium-dependent dilatation in humans

BACKGROUND

We tested the hypothesis that endothelial dysfunction underlies the association between an acute inflammatory episode and the transiently increased risk of a cardiovascular event by examining the effects of an experimental inflammatory stimulus on endothelium-dependent vasodilation.

METHODS AND RESULTS

Salmonella typhi vaccine was used to generate a systemic inflammatory response in healthy volunteers. In 12 subjects, dilatation of the brachial artery to flow and to sublingual nitroglycerin (NTG) was recorded (conduit vessel response), and in 6 subjects, venous occlusion plethysmography was used to measure forearm blood flow during intrabrachial infusion of the endothelium-dependent dilators acetylcholine (ACh) and bradykinin (BK) and the endothelium-independent dilators NTG and verapamil (resistance vessel response). Responses were assessed 16 hours before and 8 and 32 hours after vaccination. Vaccination resulted in elevations in white cell count and serum levels of interleukin-6 and interleukin-1 receptor antagonist. Eight hours after vaccination, resistance vessel responses to BK (P:=0.0099) and ACh (P:=0.0414) were markedly attenuated, and brachial artery flow-mediated dilatation was depressed. Resistance vessel responses to verapamil and NTG were unchanged, as was the conduit vessel response to NTG. Thirty-two hours after vaccination, resistance vessel responses to BK and ACh had returned to normal.

CONCLUSIONS

S typhi vaccine generates a mild inflammatory reaction associated with temporary but profound dysfunction of the arterial endothelium in both resistance and conduit vessels to both physical and pharmacological dilator stimuli. This finding might explain the association between infection and inflammation and the enhanced risk of an acute cardiovascular event.

Pharmacological management of benign prostatic hyperplasia

In men with mild to moderate BPH, pharmacotherapy is a safe and effective alternative to surgery. The primary care physician should be able to manage the treatment without referral to a urologist, provided he has undertaken appropriate steps to assure himself, and the patient, that there is no evidence of cancer of the prostate.

White coat hypertension in Zimbabwean African women

BACKGROUND

The prevalence of white coat hypertension in the Zimbabwean African female population has not been well defined.

OBJECTIVE

To determine the prevalence of white coat hypertension and to compare the cardiovascular risk profiles of those with white coat hypertension to those with sustained hypertension.

DESIGN

A cross-sectional study.

SETTING

Out patient department of Parirenyatwa Medical School Teaching Hospital, Harare, Zimbabwe.

SUBJECTS

Females with an average blood pressure of 140-160/90-105 mmHg.

INTERVENTIONS

Females with an average blood pressure of 140-160/90-105 mmHg wore 24 hour ambulatory blood pressure monitors (ABPM). Subjects with >20 mmHg systolic or >10 mmHg diastolic difference between the average out-patient blood pressure and the average awake blood pressure from the ABPM were labelled as white coat hypertensives.

RESULTS

The prevalence of white coat hypertension was 38% and the average number of risk factors per patient for the white coat group was 2.9. This result was similar to that for the sustained hypertensive group which had an average of 3.1 risk factors per patient.

CONCLUSION

White coat hypertension may be a common finding in black hypertensive Zimbabwean females who have out patient blood pressure measurements of 140-160/90-105 mmHg. The cardiovascular risk profile of these white coat hypertensives was found to be very similar to that of sustained hypertensives.

Investigation of ascites--are we doing enough?

A case of ascites with peritonitis is described. Delayed diagnosis might have contributed to the death of our patient. The current tools used in investigating ascites with peritonitis and a review of the existing guidelines for a workup of these patients are discussed. The use of the laparoscopic technique is recommended.

HIV and vasculitis: case report

Manifestation of vasculitis and HIV is now being increasingly being observed. However, clinicians need to be conscious of the possible direct association of this virus with vascular disease. It would appear that the nervous and musculoskeletal systems are most commonly affected. No systematic data exist on the benefit of pharmacological agents currently used and there is an axiomatic need to study these agents in terms of the risk/benefit.

Ethics and HIV research in Zimbabwe

A plethora of articles are now being published in both local and international journals on research activities conducted on the human immunodeficiency virus (HIV) in Zimbabwe. Some of the bioethical issues they raise, however, are neither unique to HIV nor unique to developing countries. In this article we discuss several of these issues, including the failure to provide interventions of known efficacy, ethical relevance of study design, informed consent, and exploitation. A challenge raised by much of the research in HIV/AIDS is whether, or under what conditions, it is ethical in research to fail to provide an intervention of known efficacy. The further we diverge from this situation, in which an effective, easy to implement intervention is available, to situations that resemble the controversial international clinical trials to prevent perinatal transmission of HIV the less clear the ethical mandate becomes. In relation to clinical trials the debate has focused on whether the standard of care in the United States--an expensive and complex regimen of Zidovudine--must be provided to all HIV infected pregnant women who join a research study in developing countries. Different scientists and scholars in bioethics have drawn the line differently in terms of what interventions routinely available in the developed world must be provided to research participants in developing countries. At an extreme, no one suggests that the most expensive and complex of Western tertiary care, for example, renal dialysis or coronary bypass, must be provided in research conducted in Zimbabwe. Indeed, public debates about the HIV perinatal transmission trials have not even focused on whether the women in the trials should be provided with HIV combination therapy as they would be in the West or whether they should even have the Zidovudine continued post partum.

Trends in cancer pain management

BACKGROUND

Pain is a prevalent symptom in cancer patients, affecting up to 50% of patients undergoing active cancer treatment and up to 90% of those with advanced disease. Although adequate relief can be achieved in the majority of cancer patients, pain is often treated inadequately in traditional settings and sometimes even under the management of more specialised units. In this review the authors use their experience and that of others to review the evaluation and diagnosis of pain syndromes and the principles of management. This is in keeping with increasing recognition by bodies such as the World Health Organisation and other governmental agencies who have recognised the importance of pain management as part of routine cancer care. Conducting a comprehensive assessment, competently providing analgesic drugs, and communicating with the patient and family allow effective management of pain in the cancer patient.

Prescribing patterns for the use of antithrombotics in the management of atrial fibrillation in Zimbabwe

OBJECTIVES

To assess the prescribing patterns for the use of antithrombotics in the management of atrial fibrillation.

DESIGN

A descriptive cross sectional study.

SETTING

Parirenyatwa Hospital, Harare, Zimbabwe.

SUBJECTS

The outpatient records of 200 outpatients attending the cardiac clinic (with a documented history of an irregular pulse) between January and August 1999 at Parirenyatwa Hospital, Harare, Zimbabwe were reviewed.

MAIN OUTCOME MEASURES

In addition to antithrombotic therapy prescribed at the time of review, patient information (rural or urban), relative contra-indications to antithrombotic therapy, and risk factors for stroke were identified.

RESULTS

Patients were similar in terms of age, sex, and risk factors for stroke. At least one stroke risk factor was noted in 79% of urban and 83% of rural patients. Two risk factors were noted in 26% of patients. It was noted that urban patients were more likely to have a relative contra-indication to antithrombotic therapy compared with rural patients (24% vs 10%, p = 0.028) but received antithrombotic therapy more often (38% vs 19%, p = 0.025).

CONCLUSIONS

Patients with atrial fibrillation are being inappropriately managed in terms of their major prognostic risk factor. Rural patients with atrial fibrillation receive antithrombotic therapy less frequently than urban patients despite having a similar high risk profile and fewer relative contra-indications.

Tachycardiomyopathy--a case report

This case report describes a patient presenting with atrial tachyarrhythmia and severe left ventricular failure in which rate control was associated with restoration of normal contractile function.

Management of migraine--no longer a headache

There have been important advances in the management of migraine headache. Revised diagnostic criteria, which were introduced in 1988 1 have led to more reliable assessment of the prevalence of migraine and the way it affects attendance and efficiency at work. In addition, the use of the 5HTI agonists has become established. The correct diagnosis of migraine and other headaches is of greatest importance as unless the right diagnosis is made, the right treatment cannot be given. In this article, we discuss how these changes have altered the management of migraine in adults.

Non-pharmacological termination of a supraventricular tachycardia

Patients with re-entrant supraventricular tachycardias frequently attend casualty departments for termination of their rhythm. With the advent of adenosine in the physician's pharmaceutical armoury, the ease and effectiveness of vagal stimulation is being forgotten.

Current treatment and future prospects for the management of acute coronary syndromes

The impact of ischaemic heart disease on the burden of cardiovascular disease continues to escalate worldwide, although international statistics suggest a levelling off in Western world, in the less industrialised parts of the world the effects of this disease are only beginning to be documented, nonetheless, rapid advances have been made in the diagnosis and management of the acute coronary syndromes (the term which encompasses the protean clinical manifestations of the ischaemic process). The therapeutic strategies discussed in this article cover two broad subjects that have been found to be critical in the evolution of the disease:- i. interfering with the haemostatic balance by retarding the thrombotic process; ii. modifying local and systemic vasoconstricting stimuli.

Not everything acid-fast is Mycobacterium tuberculosis--a case of Nocardia

We report a case of a 47 year old woman who presented with a history of motor convulsions and a three month history of an increasingly painful and progressively enlarging mass on the right side of her back. Neurological examination revealed generalised wasting and a right sided hemiplegia. A biopsy of the mass was taken for microbiology which reported growing branching gram positive rods after three days of incubation. A mycological diagnosis of Nocardia asteroides was made. An MRI scan revealed extensive infiltration of the fungal mass into extending from the base of the skull to fifth cervical vertebra.

Why beta blockers should be used in heart failure

Beta blockade may be beneficial for most patients with congestive cardiac failure (CCF) whether due to ischaemic or idiopathic dilated cardiomyopathy (DCM), although they are more effective if the CCF is idiopathic. Beta blockers are additive to angiotensin converting enzyme (ACE) inhibitors in their effects on CCF. Beta blockers have been shown in most studies to increase ejection fraction, cardiac output, and exercise capacity and are sometimes capable of resolving almost all the symptoms of heart failure. Treatment should begin with the smallest possible dose and this should be gradually increased to the maximum tolerated level.

Images in cardiovascular medicine: ruptured aneurysm of the sinus of Valsava

A 27 year old woman presented with a two year history of cardiac symptoms. Echocardiographic examination revealed a ruptured aneurysm of the sinus of Valsava. Of note the patient was known to be HIV positive.

Oh no, not nitric oxide!

Nitric oxide (NO) is a unique, endogenous regulatory molecule that is involved in a wide variety of physiological processes in multiple organ systems. This simple gas functions as a cellular messenger in a broad range of biological activities that include blood pressure regulation, immunomodulation and neurotransmission. It has also been implicated in a number of homeostatic functions in the cardiovascular system: it is a significant determinant of basal vascular tone and, in addition is thought to regulate myocardial contractility and platelet aggregation. Dysregulation of NO mediated effects have been implicated in the pathogenesis of essential hypertension, atherosclerosis, and the hypotension associated with septic shock. This review will focus on these multiple effects of NO in the cardiovascular system.

Clinical pharmacologist wanted--where?

Many people could define with ease the job of a cardiologist, a paediatrician or an obstetrician. However, only a few would have any clear idea of how a clinical pharmacologist might fill a day. Indeed, within the medical profession, and often within the scientific community, there has been a sneaking suspicion that clinical pharmacologists are themselves unsure of their remit. This article describes the possible role for clinical pharmacologists and different areas where they can make significant contributions to medical services.

Cytokine-induced venodilatation in humans in vivo: eNOS masquerading as iNOS

OBJECTIVE

Venodilatation is a feature of endotoxaemia and sepsis. We have tested directly the hypothesis that three cytokines (IL-1 beta, TNF alpha and IL-6) generated during endotoxaemia affect venous tone in humans in vivo by increasing NO generation and explored whether the NO comes from the iNOS or eNOS isoform.

DESIGN AND INTERVENTION

Cytokines were given into a superficial vein in very low doses sufficient only to produce changes in the study vessel. The effects of cytokines on the response to noradrenaline were examined.

RESULTS

IL-1 beta increased basal NO-induced dilatation in the study vein, and this was sufficient to attenuate the constrictor response to exogenous noradrenaline or sympathetic stimulation. The effects were maximal at 6 h and both NG-monomethyl-L-arginine and aminoguanidine caused significant reversal of the IL-1 beta effects. However, no induction of iNOS mRNA was detected in the tissue samples. Instead, mRNA encoding eNOS and GTP cyclohydrolase-1 was detected in all vessels.

CONCLUSION

The simplest explanation of these results is that IL-1 beta induces expression of GTP cyclohydrolase-1 which leads to increased generation of BH4 and activation of eNOS. This study identifies IL-1 beta as a key cytokine causing physiologically significant venodilatation in humans by increasing NO generation and suggests that this can occur even in the absence of iNOS expression.

Effects of cytokines on nitric oxide pathways in human vasculature

Proinflammatory cytokines exert a number of important effects on vascular reactivity. At one end of the spectrum, certain cytokines may induce vascular paresis leading to profound vasodilatation and hyporesponsiveness to constrictor stimuli. This may be relevant to the pathogenesis of septic shock and other types of inflammatory vasodilatation. At the other end of the spectrum, inflammatory cytokines can impair endothelium-dependent dilatation and the endothelium may lose its ability to respond to circulating hormones or autacoids. This effect may case a predisposition to vessel spasm, thrombosis or atherogenesis. Studies in human vessels suggest that interleukin-1 is particularly important as a mediator of inflammatory dilatation; the underlying mechanisms include induction of the inducible isoform of nitric oxide synthase in vascular smooth muscle, or over-production of nitric oxide from the endothelial isoform of nitric oxide synthase. Induction of the enzyme GTP cyclohydrolase 1 and consequent production of tetrahydrobiopterin contributes to the increase in the activity of endothelial nitric oxide synthase. In contrast, tumour necrosis factor-alpha considerably impairs endothelium-dependent relaxation. The mechanisms of these effects are not yet fully understood, but tumour necrosis factor can induce endothelial dysfunction in human endothelial cells in culture, and human blood vessels in vitro and in vivo. The implications of these observations for cardiovascular disease are discussed.