Fixed combination trandolapril/verapamil sustained-release: a review of its use in essential hypertension

In well designed studies in patients with mild to moderate hypertension, combinations of the sustained-release (SR) formulation of the nondihydropyridine calcium channel antagonist verapamil 120 to 240 mg/day and the ACE inhibitor trandolapril 0.5 to 8 mg/day were significantly more effective in reducing sitting systolic blood pressure (SBP) and diastolic blood pressure (DBP) from baseline than placebo. In most randomised studies, combinations of verapamil SR 120 to 240 mg/day and trandolapril 0.5 to 8 mg/day were significantly more effective in lowering sitting DBP and SBP than the corresponding monotherapies administered at the same dosage. Trandolapril/verapamil SR 2/180 mg/day provided significantly more effective 24-hour ambulatory blood pressure (BP) control than of the corresponding monotherapies. Moreover, trandolapril/verapamil SR reduced BP in patients inadequately controlled with either of the corresponding monotherapies. The antihypertensive efficacy of trandolapril/verapamil SR 2/180 mg/day was generally similar to that of other combinations of antihypertensive agents (metoprolol/hydrochlorothiazide, atenolol/chlorthalidone, lisinopril/hydrochlorothiazide, enalapril/hydrochlorothiazide) in patients with hypertension, including those with type 2 diabetes mellitus. Trandolapril/verapamil SR reduced BP in patients with hypertension and type 2 diabetes or primary renal disease, Black patients and elderly patients. Trandolapril/verapamil SR was more effective than the individual components administered as monotherapy in reducing proteinuria in patients with type 2 diabetes or primary renal disease. Trandolapril/verapamil SR had a neutral or beneficial effect on metabolic parameters (glucose, insulin, lipids) in patients with hypertension, including those with type 2 diabetes. Trandolapril/verapamil SR preserved left ventricular function in patients with heart failure. Fewer cardiac events occurred after therapy with trandolapril/verapamil SR than after trandolapril alone in post-myocardial infarction patients with congestive heart failure. The incidence of adverse events in recipients of trandolapril/verapamil SR was similar to that of the individual components, and that of other combination therapies. In placebo-controlled trials conducted in the US, headache, upper respiratory tract infections, cough, constipation, atrioventricular block (first degree) and dizziness were the most commonly reported adverse events in recipients of combinations of verapamil SR (120 to 240 mg/day) and trandolapril (0.5 to 8 mg/day). In conclusion, the fixed-dose combination of trandolapril/verapamil SR is an effective treatment for patients with hypertension, including those with type 2 diabetes. Trandolapril/verapamil SR tended to be more effective than monotherapy with either verapamil SR or trandolapril, and generally showed antihypertensive efficacy similar to that of other combination antihypertensive therapies. Current data support the use of trandolapril/verapamil SR as an alternative treatment when monotherapy with either agent is not effective. Data from large clinical trials currently being conducted will assist in fully defining the role of trandolapril/verapamil SR as a cardio- and renoprotective agent.     

Pharmacological characterisation of the goldfish somatostatin sst5 receptor

Somatostatin (somatotropin release inhibiting factor, SRIF), exerts its effects via specific G protein coupled receptors of which five subtypes have been cloned (sst1-5). Recently, SRIF receptors have also been cloned from fish tissues. In this study, goldfish sst5 receptors (gfsst5) were expressed and characterised in the Chinese hamster lung fibroblast cell line, that harbours the luciferase reporter gene driven by the serum responsive element (CCL39-SRE-Luci). The agonist radioligands [125I]-LTT-SRIF-28 ([Leu8, DTrp22, 125I-Tyr25]SRIF-28) and [125I][Tyr10]cortistatin-14 labelled similar receptor densities with high affinity and in a saturable manner (pKd: 9.99-9.71; Bmax: 300-350 fmol mg-1). 5'-Guanylyl-imidodiphosphate inhibited radioligand binding to some degree (38.5-57.9%). In competition binding studies, the pharmacological profile of SRIF binding sites defined with [125I]LTT-SRIF-28 and [125I][Tyr10]cortistatin-14 correlated significantly (r2=0.97, n=20). Pharmacological profiles of human and mouse sst5 receptors expressed in CCL39 cells correlated markedly less with those of the gfsst5 profile (r2=0.52-0.78, n > or = b16). Functional expression of the gfsst5 receptor was examined by measurement of agonist-induced luciferase expression and stimulation of [35S]GTPgammaS ([35S]guanosine 5'-O-(3-thiotriphosphate) binding. Profiles were similar to those achieved in radioligand binding studies (r2=0.81-0.93, n=20), although relative potency (pEC50) was reduced compared to pKd values. Relative efficacy profiles of luciferase expression and [35S]GTPgammaS binding, were rather divergent (r2=0.48, n=20) with peptides showing full agonism at one pathway and absence of agonism at the other. BIM 23056 (D-Phe-Phe-Tyr-D-Trp-Lys-Val-Phe-D-Nal-NH2) acted as an antagonist on the effects of SRIF-14 (pKB=6.74 +/- 0.23) on stimulation of [35S]GTPgammaS binding. Pertussis toxin abolished the effect of SRIF-14 on luciferase expression and [35S]GTPgammaS binding suggesting coupling of the receptor to G(i)/G(o) proteins. In summary, the present studies demonstrate that the gfsst5 receptor has a similar pharmacological profile and transductional properties to mammalian sst5 receptors. The difference in efficacy profiles defined using different functional assays suggests numerous, agonist specific, conformational receptor states, and/or ligand-dependent receptor trafficking.     

Synthesis and structure-affinity-activity relationships of novel benzofuran derivatives as MT(2) melatonin receptor selective ligands

A series of N-(2-phenylbenzofuran-3-yl) ethyl amide and N-(2-arylalkylbenzofuran-3-yl) ethyl amide derivatives were synthesized and evaluated as melatonin receptor ligands. The affinity of each compound for the two MT(1) and MT(2) melatonin receptor subtypes was determined by binding studies using 2-[(125)I]iodomelatonin on human embryonic kidney cell line HEK293 membrane homogenates. The intrinsic activity of the most interesting compounds was evaluated on the [(35)S]GTPgammaS binding assay. Introduction of a 2-phenyl substituent in the C-2 benzofuran position leads to an agonist compound, 10q, which binds more strongly than melatonin itself to both MT(1) and MT(2) subtypes. On the other hand, a 2-benzyl group in the same position allows MT(2) antagonist selective ligands to be obtained. The MT(2) selectivity and antagonist potency can be modulated with suitable modifications on the N-acyl and benzyl substituents, and the most selective compounds 10c and 19 show affinity ratios of 123 and 192, respectively, and bind to the MT(2) subtype similarly to melatonin itself (0.1 nM). Nevertheless, 10c acts as an MT(1) and MT(2) antagonist, whereas 19 is a partial agonist.     

Distinct haplotype profiles and strong linkage disequilibrium at the MDR1 multidrug transporter gene locus in three ethnic Asian populations

The MDR1 multidrug transporter plays a key role in determining drug bioavailability, and differences in drug response exist amongst different ethnic groups. Numerous studies have identified an association between the MDR1 single nucleotide polymorphism (SNP) exon 26 3435C>T and differences in MDR1 function. We performed a haplotype analysis of the MDR1 gene in three major ethnic groups (Chinese, Malays and Indians) by examining 10 intragenic SNPs. Four were polymorphic in all three ethnic groups: one occurring in the non-coding region and three occurring in coding exons. All three coding SNPs (exon 12 1236C>T, exon 21 2677G>T/A and exon 26 3435C>T) were present in high frequency in each ethnic group, and the derived haplotype profiles exhibited distinct differences between the groups. Fewer haplotypes were observed in the Malays (n = 6) compared to the Chinese (n = 10) and Indians (n = 9). Three major haplotypes (> 10% frequency) were observed in the Malays and Chinese; of these, two were observed in the Indians. Strong linkage disequilibrium (LD) was detected between the three SNPs in all three ethnic groups. The strongest LD was present in the Chinese, followed by Indians and Malays, with the corresponding LD blocks estimated to be approximately 80 kb, 60 kb and 40 kb, respectively. These data strongly support the hypothesis that strong LD between the neutral SNP exon 26 3435C>T and a nearby unobserved causal SNP underlies the observed associations between the neutral SNP and MDR1 functional differences. Furthermore, strong LD between exon 26 3435T and different unobserved causal SNPs in different study populations may provide a plausible explanation for conflicting reports associating the same exon 26 3435T allele with different MDR1 functional changes.     

Health-related quality of life and cost impact of irritable bowel syndrome in a UK primary care setting

OBJECTIVES: To identify the impact of irritable bowel syndrome (IBS) on health-related quality of life (HR-QOL), time off work and the utilisation and cost of health services. DESIGN: A case-control study was undertaken matching patients with IBS and controls. Quality-of-life information was collected using the Medical Outcomes Study 36-item Short Form (SF-36) health survey, EuroQOL instrument (EQ-5D) and IBS Quality-of-Life (IBS-QOL) instruments. Data on time off work was also collected. National Health Service (NHS) resource use in primary and secondary care was estimated by review of general practitioner (GP) and hospital records over a 12-month period. SETTING: Recruitment was from six GPs' surgeries in the Trent Region of the United Kingdom. PARTICIPANTS: 161 patients with IBS, as defined by the Rome Criteria I were recruited. These were compared with 213 controls matched for age, sex and social characteristics. MAIN OUTCOME MEASURES: SF-36 and EQ-5D scores; mean number of days off work; mean NHS costs per person during the 12-month study period. RESULTS: Patients with IBS had considerably lower HR-QOL than controls. They scored worse in all dimensions of the SF-36 and the EQ-5D and they had more time off work. On average patients with IBS cost the NHS 123 UK pounds (95% confidence interval: 35 UK pounds to 221 UK pounds, 1999 values) more per year than individuals in the control group (p = 0.04). CONCLUSIONS: IBS affects patients through reduced quality of life, more time off work and greater healthcare utilisation than a control group of patients without IBS. The difference in quality of life was pronounced and unusual in that it was influential in every dimension of both the SF-36 and the EQ-5D.     

New therapies and vaccines for bacterial meningitis

Acute bacterial meningitis remains an important cause of morbidity and mortality worldwide. There have recently been major advances in the prevention of the major causes of bacterial meningitis following improvements in vaccinology. The success of immunisation against Haemophilus influenzae type b infection is being mirrored with serogroup C conjugated meningococcal vaccine and pneumococcal conjugate vaccine. However, there remain major challenges, notably, serogroup B meningococcal infection and shifts in epidemiology caused by vaccine introduction. In addition, much of the world's population is unvaccinated. Therefore, improvements in management of acute bacterial meningitis are vital. In this review we attempt to summarise important advances in both prevention and treatment of acute bacterial meningitis.