A real-world analysis of outcomes and healthcare costs of patients on perindopril/indapamide/amlodipine single-pill vs. multiple-pill combination in Italy

OBJECTIVES

This analysis compared adherence, cardiovascular (CV) events and all-cause mortality incidence, and healthcare costs among hypertensive patients treated with perindopril (PER)/indapamide (IND)/amlodipine (AML) in single-pill combination (SPC) vs. multiple-pill combination, in a real-world setting in Italy.

METHODS

In this observational retrospective analysis of Italian administrative databases, adult patients treated with PER/IND/AML between 2010 and 2020 were divided into two cohorts: single-pill vs. multiple-pill. Patient data were available for at least one year before and after index date. Propensity score matching (PSM) was applied to reduce selection bias. Adherence was defined as proportion of days covered: non-adherence, <40%; partial adherence, 40-79%, and adherence ≥80%. Mortality incidence and CV events as single, or composite, endpoints were evaluated after first year of follow-up. Healthcare cost analyses were performed from the perspective of the Italian National Health Service.

RESULTS

Following PSM, the single-pill cohort included 12 150 patients, and the multiple-pill cohort, 6105. The SPC cohort had a significantly higher percentage of adherent patients vs. the multiple-pill cohort (59.9% vs. 26.9%, P  < 0.001). Following the first year of follow-up, incidence of all-cause mortality, and combined endpoint of all-cause mortality and CV events were lower in the SPC cohort compared with multiple-pill cohort. Average annual direct healthcare costs were lower in the single-pill cohort (€2970) vs. multiple-pill cohort (€3642); cost of all drugs and all-cause hospitalizations were major contributors.

CONCLUSION

The SPC of PER/IND/AML, compared with multiple-pill combination, is associated with higher adherence to medication, lower incidence of CV events and mortality, and reduced healthcare costs.

Comparing Cardiovascular Outcomes and Costs of Perindopril-, Enalapril- or Losartan-Based Antihypertensive Regimens in South Africa: Real-World Medical Claims Database Analysis

INTRODUCTION

Differences in class or molecule-specific effects between renin-angiotensin-aldosterone system (RAAS) inhibitors have not been conclusively demonstrated. This study used South African data to assess clinical and cost outcomes of antihypertensive therapy with the three most common RAAS inhibitors: perindopril, losartan and enalapril.

METHODS

Using a large, South African private health insurance claims database, we identified patients with a hypertension diagnosis in January 2015 receiving standard doses of perindopril, enalapril or losartan, alone or in combination with other agents. From claims over the subsequent 5 years, we calculated the risk-adjusted rate of the composite primary outcome of myocardial infarction, ischaemic heart disease, heart failure or stroke; rate of all-cause mortality; and costs per life per month (PLPM), with adjustments based on demographic characteristics, healthcare plan and comorbidity.

RESULTS

Overall, 32,857 individuals received perindopril, 16,693 losartan and 13,939 enalapril. Perindopril-based regimens were associated with a significantly lower primary outcome rate (205 per 1000 patients over 5 years) versus losartan (221; P < 0.0001) or enalapril (223; P < 0.0001). The risk-adjusted all-cause mortality rate was lower with perindopril than enalapril (100 vs. 139 deaths per 1000 patients over 5 years; P = 0.007), but not losartan (100 vs. 94; P = 0.650). Mean (95% confidence interval) overall risk-adjusted cost PLPM was Rands (ZAR) 1342 (87-8973) for perindopril, ZAR 1466 (104-9365) for losartan (P = 0.0044) and ZAR 1540 (77-10,546) for enalapril (P = 0.0003).

CONCLUSION

In South African individuals with private health insurance, a perindopril-based antihypertensive regimen provided better clinical and cost outcomes compared with other regimens.

Adherence to Triple Single-Pill Combination of Perindopril/Indapamide/Amlodipine: Findings from Real-World Analysis in Italy

INTRODUCTION

Single-pill combination therapy for hypertension is recognized to improve adherence to treatment. However, less is known about the benefits of triple single-pill combinations. This retrospective observational analysis aimed to assess changes in adherence when treatment was switched from perindopril (PER)/indapamide (IND) + amlodipine (AML) to PER/IND/AML single-pill combination, in Italian clinical practice.

METHODS

This analysis used data extracted from administrative databases of Italian healthcare entities. Adult patients receiving PER/IND/AML were selected, and the prescription date was considered as the index date. Among them, those who had a prescription for PER/IND + AML during the 12 months before the index date and a prescription of PER/IND/AML during 6 months of follow-up were included. Adherence was calculated as the proportion of days covered (PDC: PDC < 40%, non-adherent; PDC = 40-79%, partially adherent; PDC ≥ 80%, adherent).

RESULTS

Among the identified patients, 158 were exposed users and were included in the analysis. When patients were compared before and after switch to triple single-pill combination, the proportion of adherent patients was significantly higher with PER/IND/AML single-pill combination (75.3%) than with PER/IND + AML combination (44.3%) (P < 0.05). Conversely, the proportion of non-adherent patients was lower with the PER/IND/AML single-pill combination (14.6%) vs PER/IND + AML (17.7%) (P < 0.001).

CONCLUSION

This real-world analysis showed that switching to a triple single-pill combination could offer an opportunity to improve adherence to antihypertensive treatment in real-life clinical practice.

A retrospective study: efficacy of an originator versus a generic formulation of simvastatin in patients who suffer from hyperlipidaemia

BACKGROUND

South Africa is home to a multi-ethnic society with a large range of cultures and lifestyles. Cardiovascular disease is a major cause of morbidity and mortality. South Africa is known to have one of the highest incidence rates of hypercholesterolaemia in the world, especially among the Caucasian population.

AIM

The aim of this retrospective chart review was to establish whether a multisource simvastatin (Simvotin®, Ranbaxy, a Sun Pharma company) maintained the cholesterol-lowering effect after switching from the innovator brand Zocor® (MSD South Africa) in the public-sector hospitals. Since prescribers often doubt the registration requirements of multisource products based on bioequivalence alone, this research was done to confirm similar clinical outcomes in a real-world setting.

METHODS

More than 200 charts were identified from patients treated for hyperlipidaemia. Patients were treated for at least six months prior to and again six months after the switching of brands in order to meet criteria to be eligible for inclusion. The lipid values at initiation of therapy as well as before switching (visit 1 and 2) had to be available and again six months after treatment on the multisource product (visit 3).

RESULTS

No significant change was observed in the lipid control after switching, confirming similarity.

CONCLUSION

This real-world evidence should allay any fears of generic inferiority of this important medicine in the treatment and prevention of high cardiovascular risk in patients requiring lipid-lowering therapy.

Short-course, low-dose oral betamethasone as an adjunct in the treatment of acute infective sinusitis : a comparative study with placebo

OBJECTIVE

To assess the effect of a short course of low-dose oral corticosteroid used as an adjunct to antimicrobials in patients with acute infective sinusitis.

STUDY DESIGN AND PATIENTS

Double-blind, randomised, placebo-controlled study including 42 patients with a clinical diagnosis of acute infective sinusitis. The study was performed at three primary healthcare sites in South Africa during the period January-November 2003.

INTERVENTION

Two equal groups received either betamethasone 1mg orally (n = 21; the treatment group) or placebo tablets (n = 21; the placebo group) once a day in the morning for five consecutive days. All patients received amoxicillin-clavulanic acid 625mg orally, three times daily for 5 days.

MAIN OUTCOME MEASURE

Patients rated symptoms on a daily symptom score card for 5 days and were examined by the investigator at diagnosis (day 0) and on the second visit (day 6).

RESULTS

Headache, facial pain, nasal congestion and dizziness improved significantly from baseline in the treatment group compared with the placebo group over 5 days of treatment (p = 0.028, p </= 0.047, p </= 0.04 and p </= 0.051, respectively). Percussion tenderness improved significantly (p = 0.049) and clearance of purulent secretions almost reached significance (p = 0.058) in the treatment group compared with the placebo group.

CONCLUSION

This study suggests a benefit of oral corticosteroid added to antimicrobial treatment of acute sinusitis and documents the first successful use of a short course of low-dose oral corticosteroid in patients with acute infective sinusitis.

Effect of levamisole on the immune response of patients with schistosomiasis after treatment with praziquantel

Successful therapy with praziquantel in schistosomiasis is dependent on a normal host immune system, i.e. the recognition of parasite antigen, to be effective in eradicating the parasite. Levamisole, a nonspecific immunomodulator, has been hypothesised to normalise deficient cell-mediated immunity. The aim of this study was to investigate the effect of levamisole on the immune response seen after presumed curative doses of praziquantel. After ethical approval, 29 male volunteers infected with Schistosoma haematobium were recruited and randomised to receive orally either (a) levamisole 5 mg/kg for 2 consecutive days, plus praziquantel 40 mg/kg as a single dose, (b) levamisole 5 mg/kg for 2 days, or (c) praziquantel 40 mg/kg as a single dose. Blood samples were collected on day 0 and again 3 months later for differential counts and specific IgG and IgE to whole-worm-antigen, as well as for the detection of eosinophil cationic protein (ECP). Levamisole treatment alone resulted in a significant drop in circulating eosinophil counts, i.e. a median (95% confidence interval) drop of 6.0 (1;7)%. Eosinophil counts did not change significantly after praziquantel therapy alone. ECP values were significantly reduced with levamisole alone and praziquantel alone, i.e. respective median (95% confidence interval) drops of 33.58 (18.94; 55.9) and 16.54 (3.6; 33.5) microg/L (p < 0.05). The group receiving combination therapy demonstrated significant increases in specific IgG values (p = 0.02) with no decline in ECP levels and eosinophil counts compared with baseline values. Levamisole alone had no effect on egg counts. In conclusion, levamisole inhibited circulating eosinophils and eosinophil activation when given alone, but caused immune stimulation when combined with praziquantel. The exact mechanism of action still needs to be determined.

Effect of betamethasone-loratadine combination therapy on severe exacerbations of allergic rhinitis : a randomised, controlled trial

OBJECTIVE

Corticosteroids are effective in controlling the inflammatory component of allergic rhinitis; however, evidence for the clinical efficacy of systemic corticosteroids in this disease is sparse. It is further common practice to combine oral corticosteroids with antihistamines in the treatment of acute exacerbations of allergic rhinitis. The aim of this study was to investigate the effect of low-dose oral betamethasone alone and in combination with loratadine in a group of patients with allergic rhinitis with clinically significant obstruction.

METHODS

In this parallel, double-blind, active controlled multicentre study, 299 patients with severe allergic rhinitis were randomly allocated to either betamethasone 1.0mg or betamethasone 1.0mg plus loratadine 10mg or betamethasone 0.5mg plus loratadine 10mg or loratadine 10mg alone for 5-7 days. Total symptom scores, nasal obstruction, and doctor and patient perception of improvement were measured as markers of disease severity.

RESULTS

Although not statistically significant, both betamethasone 1.0mg regimens resulted in a total symptom score difference of at least 1 or more from loratadine (i.e. mean [SD] change in total symptom score of 4.10 [3.10] and 4.40 [3.62] vs 3.10 [3.30], respectively, for betamethasone 1.0 mg plus loratadine, betamethasone 1.0 mg and loratadine). All corticosteroid-containing regimens were significantly better than loratadine alone with regard to the patients' (p < 0.013) and doctors' (p < 0.009) perceptions of improvement. They significantly favoured loratadine in combination with betamethasone over single-drug therapy (i.e. odds ratio: investigator ratings 0.49, 0.36 and 0.45, and patient ratings 0.47, 0.40 and 0.43, respectively, for 0.5 mg and 1.0 mg betamethasone plus loratadine and betamethasone 1.0 mg alone vs loratadine alone). Betamethasone 1.0mg plus loratadine also resulted in significant reduction of the relapse rate compared with the other therapies.

CONCLUSIONS

This study demonstrated the benefit of a short course of a systemic low dosage of corticosteroids with and without antihistamine therapy during acute severe exacerbations of allergic rhinitis. Combination treatment with betamethasone 1.0mg and loratadine 10mg was significantly better in relieving symptoms of hayfever as experienced by patients. This was the first study to give evidence of benefit of systemic low-dose corticosteroids with and without an antihistamine in patients with acute exacerbations of allergic rhinitis.

Randomized, parallel-group, double-blind, controlled study to evaluate the efficacy and safety of carbohydrate-derived fulvic acid in topical treatment of eczema

Background

The purpose of this study was to evaluate the efficacy and safety of carbohydratederived fulvic acid (CHD-FA) in the treatment of eczema in patients two years and older.

Methods

In this single-center, double-blind, placebo-controlled, parallel-group comparative study, 36 volunteers with predetermined eczema were randomly assigned to receive either the study drug or placebo twice daily for four weeks.

Results

All safety parameters remained within normal limits, with no significant differences in either group. Significant differences were observed for both severity and erythema in the placebo and CHD-FA treated groups, and a significant difference was observed for scaling in the placebo-treated group. With regard to the investigator assessment of global response to treatment, a significant improvement was observed in the CHD-FA group when compared with the placebo group. A statistically significant decrease in visual analog scale score was observed in both groups, when comparing the baseline with the final results.

Conclusion

CHD-FA was well tolerated, with no difference in reported side effects other than a short-lived burning sensation on application. CHD-FA significantly improved some aspects of eczema. Investigator assessment of global response to treatment with CHD-FA was significantly better than that with emollient therapy alone. The results of this small exploratory study suggest that CHD-FA warrants further investigation in the treatment of eczema.

Generic versus non-generic formulation of extended-release clarithromycin in patients with community-acquired respiratory tract infections: a prospective, randomized, comparative, investigator-blind, multicentre study

BACKGROUND AND OBJECTIVE

There is a general concern about the use of multisource (generic) antibacterials in the clinical setting with registration based solely on bioequivalence data. In order to address this concern, two modified-release formulations of clarithromycin (i.e. the originator Klacid XL and the generic Klarithran MR) were compared in patients with acute community-acquired respiratory tract infections.

METHODS

Patients presenting with tonsillopharyngitis, sinusitis or pneumonia were randomized to receive either of the test drugs provided they clinically qualified for empirical clarithromycin treatment. The study endpoints were clinical and bacteriological cure rates, tolerability and safety. The study was designed to test for non-inferiority with regard to cure rates.

RESULTS

The main outcome of this study was that both agents had similar clinical (non-inferior) and bacteriological cure rates and demonstrated no difference in tolerability in patients. The study also demonstrated the clinical efficacy of clarithromycin when used as empirical treatment in patients with respiratory tract infections in community practice (i.e. 95% clinical cure rate).

CONCLUSION

The clarithromycin extended-release multisource product (Klarithran MR) does not differ significantly from the originator (Klacid XL) and the clinical cure rate of the generic formulation is non-inferior to that of the originator. The two formulations are tolerated similarly.

Perindopril: do randomised, controlled trials support an ACE inhibitor class effect? A meta-analysis of clinical trials

BACKGROUND

Due to the lack of face-to-face trials between ACE inhibitors, clinicians and third-party funders may assume they provide similar outcomes. As a result, ACE inhibitors may be prescribed interchangeably and deemed to provide the same outcomes for all patients when used chronically, that is for more than six months.

OBJECTIVE

This meta-analysis aims to dispute the assumption of a class effect when prescribing ACE inhibitors (ACEIs), since the evidence from all the clinical trials is not uniform and therefore a direct comparison is impossible.

METHODS

Published randomised, controlled trials were selected using an applicable literature search for all ACEIs, irrespective of drug combination, for any cardiovascular outcome (both composite and individual outcomes were included). The average length of ACEI exposure per trial had to be longer than six months). This meta-analysis was performed using odds ratios as the parameter of efficacy in a fixed-effects model.

RESULTS/CONCLUSION

Perindopril resulted in significantly fewer patients reaching the primary endpoint versus all other ACEIs combined. The results were consistent for myocardial infarction, stroke and mortality (5 vs 11%, p = 0.0001). Perindopril alone or as part of combination therapy in clinical trials seemed to deliver clear and consistent outcome differences compared to other ACEI trials. In the presence of positive outcomes from robust randomised, controlled trials for perindopril, one cannot assume a class effect for all ACEIs.

Intravenous fluid therapy: a randomized controlled trial to investigate the effectiveness of the IV(2) flow medical device

OBJECTIVES

To investigate the hypothetical benefits of the IV(2) flow medical device.

BACKGROUND

Intravenous fluid administration is a standard hospital procedure with assumed inadequacies. The IV-Event Study [Fraser N, Nel G, Snyman J & Wessels F (2004) IV-EVENT Study: Intravenous Infusion Therapy--Management and Adverse Events. Data on File: Varori International (Pty) Ltd., Centurion, South Africa] quantified these inadequacies; The 'Stargait' intervention trial investigated the effectiveness and possible cost-benefit of the IV(2) flow. The IV(2) flow is intended for routine use with gravitational intravenous infusion sets. The IV(2) flow should reduce the incidence rate of adverse events and maintain a set flow rate.

METHOD

Nursing staff assisted by study assessors captured relevant data. Consented patients were enrolled for the period of their prescribed infusions. Intervention. The Stargait Trial compared the treatment group (standard gravitational sets with the IV(2) flow) with the control group (standard gravitational infusion sets without IV(2) flow). The difference in observed events and the cost benefit derived from this were measured.

RESULTS

A total of 2387 drip hours were observed in 52 patients. The adverse event rates were: Control group (without IV(2) flow) 33.8%. The treatment group (IV(2) flow) 15.4%. This 55% reduction is statistically significant (p = 0.0069). Adverse event related monetary wastage (labour and consumables) is reduced by 76% for infusion bags in the intervention group (with IV(2) flow). There was a significant difference between the treatment group and control group as far as deviation in flow rate was concerned (p = 0.00818). The mean deviation of the IV(2) flow group was just more than 5 ml per hour. The standard line group had a mean deviation of more than 30 ml per hour.

CONCLUSION

Gravitational intravenous therapy compromises quality of patient care. The Stargait Trial has proven the care-effectiveness and cost-effectiveness of the IV(2) flow.

RELEVANCE TO CLINICAL PRACTICE

The IV(2) flow improves quality of patient care and reduces associated wastage.

Brown Coal Derived Humate Inhibits Contact Hypersensitivity; An Efficacy, Toxicity and Teratogenicity Study in Rats

OBJECTIVES

The effects of two humate products were compared to that of prednisolone on a contact hypersensitivity rat model.

METHODS

Rats, sensitized with dinitrofluorobenzene (DNFB), were placed on a daily oral treatment of 61 mg/kg BW of humate derived from either leonardite or bituminous coal or on prednisolone at one mg/kg BW and challenged 6 days later with a topical application of DNFB to the right ear. The inflamed ears were measured daily. In a toxicity study rats were exposed to daily oral treatment of leonardite humate at 1,000 mg/kg BW for 1 month. A teratogenicity study was done where pregnant rats were treated with 500 mg/kg BW on days 5 to 17 of pregnancy.

RESULTS

Only the leonardite humate compared favourably with prednisolone in suppressing contact hypersensitivity. No signs of toxicity were observed and weight gain was normal during the 6-day and 1 month treatments and during the teratogenicity study with the leonardite humate. However, the rats on the other two products experienced slower weight gain.

CONCLUSION

The identification of a naturally occurring nontoxic compound with anti-inflammatory activity is exciting and merits further evaluation in the treatment of patients suffering from inflammatory conditions.

Evaluation of cisplatin and a novel platinum polymer conjugate for drug toxicity and drug distribution in mice

The toxicity and distribution of cisplatin and two novel platinum (Pt) polymer conjugates (Pt-6 and Pt-7) were determined in serum and tissue of BALB/c mice at specific time points after i.p. administration of a drug bolus containing identical Pt concentrations. Pt concentrations were determined in serum, liver and kidney at 5 and 15 min, respectively, after drug administration by inductively coupled plasma mass spectrometry. It was found that the Pt polymer Pt-7 gave rise to a considerably lower Pt concentration in serum and considerably higher concentration in liver and kidney than cisplatin. LD25 measurements indicated that the Pt-7 polymer is considerably less toxic than cisplatin. In vitro experiments and determination of IC50 values in a variety of human tumor cell lines, normal lymphocytes and fibroblasts confirmed that Pt-6 and Pt-7 polymers are 40-500 times more toxic for tumor cells than for normal cells, perhaps reflecting preferential uptake. The toxicity of cisplatin was found to be only 1.6-40 times more effective in tumor cells. These inter-relationships are supported by the observation that the tumor enrichment factor (TEF) for cisplatin is only in the region of 6, and much lower than for Pt-6 and Pt-7, where TEFs are in the region of 40 and 150, respectively. These results demonstrate that the Pt polymer conjugates exhibit greater tumor specificity than cisplatin, killing tumor cells more effectively while being considerably less toxic for normal cells. It is concluded that the Pt polymer conjugates may be superior for cancer therapy and warrant further testing to assess their full clinical potential.

Arylamine N-acetyltransferase (NAT2) genotypes in Africans: the identification of a new allele with nucleotide changes 481C>T and 590G>A

This study was carried out to characterize the distribution of NAT2 allelic variants among a sample of three African populations. We determined the frequencies of major NAT2 allele clusters (NAT2*4, *6, *7 and *14) using PCR/restriction fragment length polymorphism and sequencing techniques. The genotypes predict slow acetylator phenotypes of 49, 38 and 52% among Tanzanians, Venda and Zimbabweans, respectively. The most common genotype was NAT2*4/*5. NAT2* 5 was the most common allele while NAT2* 7 was the least common. A new allele with two base changes occurring together, 481C>T and 590G>A, is reported. The frequency of the occurrence of the combination 481C>T and 590G>A, was found to be 9% (30/326), 7% (14/192) and 8% (18/234) among Zimbabweans, Venda and Tanzanians, respectively. The allele has been named NAT2*6E. Among Africans, the change 481C>T is not only associated with 341C>T (i.e. the NAT2* 5 allele cluster) as in other populations, but also with 590G>A on the same allele.

Genetic polymorphism of CYP2D6 and CYP2C19 in east- and southern African populations including psychiatric patients

OBJECTIVES

The study was carried out to investigate the distribution of cytochrome P450 2D6 (CYP2D6) and CYP2C19 genotype frequencies in three African populations and to compare these frequencies between healthy individuals and psychiatric patients.

METHODS

Three hundred and eighty-four subjects from South Africa (Venda), Tanzania, and Zimbabwe who consented to the study were genotyped for CYP2D6 (CYP2D6*1, *2, *3, *4, *5, and *17) and CYP2C19 (CYP2C19*1, *2, and *3) by PCR-RFLP (polymerase chain reaction restriction fragment length polymorphism) techniques.

RESULTS

The genotypes for CYP2D6 predicted a poor metabolizer frequency of 2.3% (2/88) in Tanzanian psychiatric patients, 1.9% (2/106) in Tanzanian healthy controls and 2.6% (2/76) in the South African Venda. The low-activity CYP2D6*17 allele frequency was higher in psychiatric patients (30%, 53/176) than in healthy individuals (20%, 43/212) in Tanzanians. The frequencies for CYP2C19*2 genotypes were predictive of a low prevalence of poor metabolizers (PMs). The CYP2C19*3 allele was absent in the three populations studied. There was no difference in CYP2D6 or CYP2C19 PM genotype frequencies between psychiatric patients and healthy subjects.

CONCLUSION

The genotype results predict a low prevalence of people with deficient CYP2D6 and CYP2C19 activity among linguistically (Bantu) related populations of East and Southern Africa. The high frequency of the low-activity CYP2D6*17 allele predicts that the Bantu people have a reduced capacity to metabolise drugs that are CYP2D6 substrates.

Lack of bioavailability of mebeverine even after pretreatment with pyridostigmine

OBJECTIVE

After the oral administration of mebeverine to animal or human, measurable concentrations of the drug have never been found in the plasma. The ex vivo hydrolysis of mebeverine can be blocked by esterase inhibitors. In the present study, human volunteers were pretreated with pyridostigmine to attempt to improve the bioavailability of the parent drug.

METHODS

Following a single-blind, random design, 12 normal human volunteers received orally either placebo or 60 mg pyridostigmine, followed 2 h later by 405 mg mebeverine. Blood samples were drawn intermittently for 4 h and were spiked immediately with neostigmine in order to block ex vivo hydrolysis.

RESULTS

Even after pretreatment with pyridostigmine, the plasma samples failed to reveal detectable concentrations of mebeverine. Pyridostigmine pretreatment mediated a significantly higher peak concentration of veratric acid, the acid moiety resulting from hydrolysis of mebeverine.

CONCLUSION

As mebeverine seemingly undergoes complete presystemic hydrolysis, it seems unlikely that the effects of the drug could be mediated centrally. Furthermore, as it is unlikely that sufficient mebeverine traverses the intestine to exert a local effect on the colon (i.e., the time-course of veratric acid plasma levels does not support such a conclusion), the therapeutic effect of the drug, if any, has to be ascribed to an active metabolite. However, the hydrolysis products of mebeverine are not known to be pharmacologically active.

Lack of effect of amitriptyline on risperidone pharmacokinetics in schizophrenic patients

The interaction between plasma concentrations of the tricyclic antidepressant amitriptyline and the metabolism of the new antipsychotic risperidone was studied in 12 patients with chronic schizophrenia. Each patient received 3 mg risperidone twice a day for 28 days. Amitriptyline was coadministered at doses of 50 mg/day on day 15 and 100 mg/day on days 16 to 21. Amitriptyline did not significantly affect the mean plasma concentrations or pharmacokinetics of risperidone in schizophrenic patients or influence the antipsychotic fraction (the total concentration of risperidone and 9-hydroxyrisperidone, its primary and biologically active metabolite). These results suggest that risperidone dose need not be adjusted when coadministered with amitriptyline at doses up to 100 mg/day in schizophrenic patients.

Effects of calcitriol on eosinophil activity and antibody responses in patients with schistosomiasis

OBJECTIVE

Parasitic infestations are known to elicit T-helper lymphocyte type 2 (Th-2) reactions, characterized by a pronounced eosinophila and high IgE levels. In humans both elevated specific IgE levels and eosinophil counts are associated with resistance to reinfection with schistosomiasis. This study aimed to establish whether the Th-2 reaction could be enhanced with calcitriol (vitamin D3). Calcitriol has been shown to cause a shift from Th-1 to Th-2 type reactions when applied locally to the skin.

METHODS

Fifty-nine patients with Schistostoma haematobium infection were randomized to one of four treatment modalities, i.e. (a) praziquantel (PZQ) 60 mg.kg-1 orally on day 1, (b) PZQ 60 mg.kg-1 on day 1 plus calcitriol 1 microgram per day orally for 5 consecutive days, (c) calcitriol 1 microgram per day for 5 consecutive days or (d) placebo. Blood for differential counts, eosinophil cationic protein (ECP), specific IgE and IgG to whole-worm antigen, as well as urine samples for egg counts, were collected on days 0 and 21.

RESULTS

Baseline values did not differ significantly between the groups. Calcitriol alone resulted in significant increases in circulating lymphocytes (median increase of 5.5%) and the percentage of eosinophil vacuolization (mean increase 28%). It, however, significantly decreased ECP levels (mean decrease 46%). PZQ in combination with calcitriol significantly enhanced production of specific IgE (mean increase 213%) and IgG (mean increase of 170%) and tended to increase eosinophil vacuolization (mean increase 22%). All these changes also differed significantly from those in the placebo group. The specific IgE and IgG levels were also significantly higher than the already increased levels seen with PZQ treatment only. ECP levels were, however, not significantly affected by combination therapy, whereas PZQ alone significantly enhanced ECP production (mean increase 93%).

CONCLUSIONS

The increases in specific IgE responses and percentage of eosinophil vacuolization favour a Th-2 type of reaction. The ECP values viewed in isolation may, paradoxically, indicate a Th-1 response; this could, however, have been an artefact due to the method of ECP detection ex vivo. Finally, it would seem that calcitriol does cause some immune augmentation when combined with PZQ therapy in patients with schistosomiasis. However, long-term follow-up is needed to prove that these findings would translate into resistance against re-infection.

Effects of metoclopramide and tropisetron on aldosterone secretion possibly due to agonism and antagonism at the 5-HT4 receptor

OBJECTIVE

Part of the prokinetic activity of metoclopramide can possibly be ascribed to agonist activity at 5-HT4 receptors. The 5-HT3 antagonist tropisetron is thought to act as an antagonist at 5-HT4 receptors. In the present study aldosterone secretion in response to the administration of these two drugs was explored to examine the role of the 5-HT4 receptor in aldosterone secretion.

METHODS

Following a single-blind, random design, ten normal male volunteers received one of the following regimens on three occasions, with at least 2-week intervals: metoclopramide 10 mg i.v.; tropisetron 5 mg by slow i.v.i., or; tropisetron by slow i.v.i., followed by 10 mg metoclopramide i.v.

RESULTS

In response to metoclopramide alone the mean plasma aldosterone level rose significantly to 149% of basal level and remained significantly elevated for the next 20 min. With tropisetron alone, there was a significant 37.8% drop at 60 min and the aldosterone levels remained low for the duration of the experiment. Metoclopramide reversed the decline mediated by tropisetron significantly at 30 and 90 min. Aldosterone levels after the latter regimen also did not differ significantly from baseline at any time period.

CONCLUSION

These results would suggest the existence of a tonic stimulatory influence of 5-HT via 5-HT4 receptors on aldosterone secretion, which could be augmented by metoclopramide and blocked by tropisetron. However, the effect of tropisetron per se should be interpreted with caution given the lack of a saline group.

The proportional cumulative area under the curve of paracetamol used as an index of gastric emptying in diabetic patients with symptoms of gastroparesis

1. The foreshortened 2 h method of measuring liquid gastric emptying (i.e. the proportional cumulative area under the curve of paracetamol) was utilized in diabetic patients in order to detect both gastroparesis and the influence of metoclopramide, a known prokinetic drug, on this condition. 2. Metoclopramide, 10 mg intravenously, caused a significant increase in the median PCAUC from 20 min onwards. 3. In this study delayed gastric emptying was defined as a %PCAUC without pretreatment lower than the 5% percentile at 40, 60 and 90 min for normal volunteers. According to this criterion seven of the 10 patients with clinical symptoms of gastroparesis and/or peripheral neuropathy had delayed gastric emptying. 4. The PCAUC method would therefore seem to be a reliable model for investigating gastric emptying in diabetics and the effects of various prokinetic drugs on this condition.

A noninvasive evaluation of baroreceptor sensitivity with the Valsalva maneuver and phenylephrine methods

In a double-blind crossover study, we compared baroreceptor sensitivity (BS) and latency, derived from the phenylephrine method with BS and latency derived from phase IV of the Valsalva maneuver (VM), using the Finapres, a noninvasive blood pressure monitor. Ten healthy volunteers were enrolled in the study and BS was determined with placebo, atropine (0.03 mg/kg) and atenolol (10 mg) and was expressed as the linear relation between the change in RR interval following the blood pressure rise induced by either phenylephrine or phase IV of the VM (i.e., after cessation of straining). Baseline baroreceptor sensitivity (p<0.001) and baroreceptor sensitivity in the presence of atropine (p<0.02) was smaller with the VM but no differences in baroreceptor sensitivity between the two methods were evident after atenolol. Although no linearity existed between the two methods under any of the experimental conditions, baroreceptor sensitivity in the presence of atropine was significantly smaller (p<0.01)(and latency delayed (p<0.08)) compared to atenolol-induced changes with both methods. We found excellent correlation between baroreceptor sensitivity derived from the ECG tracing and Finapres recorded beat-to-beat pulse intervals (p<0.001; r>0.8, under all conditions) although the correlation after atropine was not as close (p<0.01; r=0.7). The smaller baroreceptor sensitivity induced by the Valsalva maneuver with placebo and atropine, but not with atenolol, suggests a parasympathetically influenced vasodilation, and sympathetically medicated tachycardia during phase IV of the VM.

The influence of betahistine on the dynamics of the cutaneous hypersensitivity reaction in patients with grass pollen allergy

Histamine has been well documented as an immune modulator, but the dynamics of a number of histamine receptor agonists and antagonists have not been similarly established. The aim of this study was to determine the effect of betahistine (an H3-receptor blocker with partial H1- and H2-agonism) on the dynamics of the cutaneous hypersensitivity reaction. The skin blister technique was used to collect inflammatory cells after intradermal (i.d.) administration of grass pollen antigen, histamine and betahistine to 11 atopic volunteers. In this open, cross-over study, volunteers were randomly allocated to five treatment protocols i.e. (a) histamine 1 microgram i.d.; (b) betahistine 57, 114 and 285 micrograms i.d.; (c) i.d. grass pollen antigen; (d) (c) plus oral betahistine; (e) (c) plus oral betahistine, cetirizine, (H1-blocker) and cimetidine (H2-blocker). Blister fluid containing cells were collected on microscope slides at 6 and 24 h after i.d. injections. The areas of the wheal and flare and of induration were measured, respectively, at 0.25, and, 1, 6 and 24 h. Combined oral therapy with cetirizine, cimetidine and betahistine reduced the area of grass pollen-induced induration significantly at all time periods, but caused a significant increase in eosinophil and neutrophil vacuolisation during the late phase reaction. This did not occur with orally administered betahistine alone. Intradermal betahistine induced significantly more neutrophil and eosinophil vacuolization than histamine and, in contrast to the latter, also mediated a concentration-dependent late phase induration. The results of this study suggest that the H3-receptor regulates a feedback system in conjunction with that previously proven for the H2-receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

The countering of diazoxide-induced vasodilatation by tenoxicam in normal volunteers

The effect of the nonsteroidal anti-inflammatory drug, tenoxicam, on diazoxide-induced lowering of standing diastolic blood pressure was explored in 10 normal volunteers. With diazoxide there was a significant fall in the 5-min standing diastolic pressure, i.e. a median drop of 15.5, 11.0, 9.5 and 7.0 mm Hg at 10, 35, 75 and 105 min, respectively, but with the tenoxicam-diazoxide regimen this pressure did not differ significantly from baseline at any time point. Tenoxicam did not modify the diazoxide-induced changes in blood glucose and plasma insulin. It may be that prostaglandins normally contribute to the lowering of peripheral vascular resistance, or that acutely-administered diazoxide enhances the release of vasodilatory prostaglandins.

Effects of glycopyrrolate on capsaicin-induced cough in normal volunteers treated with captopril

The effects of inhibition of angiotensin converting enzyme (ACE) and glycopyrrolate on cough caused by inhaled capsaicin were investigated in a double-blind, randomised cross-over study in twelve normal volunteers. The capsaicin challenge was performed before and 2 h after dosing with 75 mg captopril or matched placebo given orally, and 20, 40 and 60 min after giving 1 mg glycopyrrolate i.v. to each subject. Captopril and placebo did not alter the cough response when compared to baseline. Glycopyrrolate, however, caused a significant increase in the threshold sensitivity (D2) from baseline, and a significant decrease in the total cough response at 40 and 60 min both after captopril and placebo. The D2-baseline and D2-40 min after glycopyrrolate (mean SD), respectively, were 3.2 (1.0); 17.9 (4.2) after placebo and 2.5 (8.5); 23.6 (6.9) after captopril. Elimination of vagal influences implies attenuation of the effects of tachykinins but not those prostaglandins. We postulate that tachykinins, such as substance P, play a more important role than prostaglandins in capsaicin-induced cough. We conclude that the vagus is important in the capsaicin-induced cough reflex, but, as suppression of this reflex by glycopyrrolate was delayed, the relevant receptors are either poorly accessible peripheral receptors or they are located in the central nervous system.

Dexfenfluramine-induced prolactin release as an index of central synaptosomal 5-hydroxytryptamine during treatment with fluoxetine

Serotonin (5-HT) stimulates prolactin release. In the present study the ability of dexfenfluramine to increase serum prolactin was used as an index of central 5-HT function after acute and chronic pretreatment of volunteers with fluoxetine. Following a single-blind, random design, on each experimental day each volunteer received 60 mg dexfenfluramine taken with 250 ml water at zero time and no other treatment, or pretreatment with 40 mg fluoxetine at -8 h, or pretreatment with 20 mg fluoxetine daily for 14 days, or the dexfenfluramine alone 14 days after cessation of 14 days of fluoxetine treatment. There were no significant differences between the prolactin levels found after dexfenfluramine only, dexfenfluramine after a single dose of fluoxetine, and dexfenfluramine 14 days after cessation of fluoxetine treatment. However, baseline levels and those 3 and 4 h after dexfenfluramine administration were significantly lower after pretreatment for 14 days with fluoxetine compared to the other three regimens. At 5 h the levels were still lower, but not significantly so, as the prolactin level rose approximately 110% compared to the baseline and 4 h values. The reduction in the median basal serum prolactin level by almost two-thirds after 14 days of fluoxetine treatment suggests a decrease in 5-HT turnover. Furthermore, the delayed surge in prolactin release produced by dexfenfluramine with this regimen suggests 5-HT release from a less accessible pool or accumulation of fluoxetine in the neuronal cytosol and consequent competitive inhibition of 5-HT transport out of the nerve terminal.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of captopril and naloxone on the Valsalva manoeuvre and systolic time intervals in healthy volunteers

1. The aim of the study was to ascertain whether the inhibition of the sympathetic nervous system by angiotensin-converting enzyme (ACE) inhibitors is mediated by endogenous opioids. Naloxone was used to evaluate the effects of the latter on systolic time intervals (STI) and Valsalva manoeuvre-induced blood pressure and heart rate changes. 2. Baseline recordings were done in 12 healthy male volunteers and repeated 2 h after oral administration of 75 mg of captopril and again after naloxone 0.4 mg/kg was administered intravenously over 10 min. 3. After captopril there was a significant reduction in systolic (P < 0.02) and mean blood pressure (P < 0.04) without any changes in heart rate. Furthermore, captopril increased the Valsalva ratio (P < 0.06) but did not influence inotropism as indicated by STI. Naloxone did not influence any of these findings. 4. The changes in the Valsalva ratio after captopril were mediated by an increase in the maximum bradycardia in nine of the 12 subjects. 5. The results indicate that endogenous opioids do not play a role in the putative sympatholytic effect of ACE inhibition.

Effect of longterm cetirizine treatment on the cutaneous hypersensitivity reaction in patients with grass pollen allergy

In short-term studies cetirizine effectively reduces the early and late phases of the cutaneous hypersensitivity reaction. The aim of this study was to determine its long-term effects on both the vascular and cellular components of the reaction. The skin blister technique was used to collect inflammatory cells after intradermal administration of grass pollen antigen to 10 atopic volunteers. They were treated for 3 months with 10 mg cetirizine twice daily. Tests were done at baseline, before, and 7, 30 and 90 days after initiation of treatment. Blister fluid containing cells was collected on microscope slides at 6 and 24 hours. The area of induration was measured at 0.25, 1, 6, 10 and 24 h. Cetirizine significantly reduced the peripheral blood eosinophil count at 30 and 90 days (75% and 40% reduction respectively); there was no significant change after only one week's therapy. Eosinophil recruitment to and activation in the area of antigen administration were already maximally reduced after 7 days, namely a reduction of 54, 52 and 59% at 10 h, and of 55, 68 and 66% at 24 h, respectively, at 7, 30 and 90 days. The area of induration was significantly reduced after one week of therapy. There was a general tendency towards an increase in the reduction at 30 and 90 days, which reached significance only at the 24 h observation; there was a 24, 51 and 48% reduction from baseline at, respectively, 7, 30 and 90 days. The data clearly show a progressive reduction of induration as well as of cellular events over time.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of histamine receptor antagonists on the dynamics of the cutaneous hypersensitivity reaction in patients infected with schistosoma haematobium

The biphasic cutaneous hypersensitivity response elicited by intradermal administration of S. haematobium antigen to patients with schistosomiasis may be used as a model for drug effects on cell dynamics. As the effects of H1- and H2-blockade, and the possible involvement of H3-receptors, have not been elucidated, we have examined the effects of combinations of cetirizine, cimetidine and betahistine on the response of patients with confirmed schistosomiasis. The skin blister technique was used. After intradermal administration of antigen, blister fluid containing inflammatory cells was collected on microscope slides at 6 and 24 h, and a differential cell count was done; and the area of induration was measured at 0.25, 1, 6 and 24 h. These baseline tests were repeated after 3 days of pretreatment with cetirizine 20 mg/d, after the addition of cimetidine 1200 mg/d for 3 further days, and finally after adding on betahistine 32 mg/d for 3 days. Simultaneous H1- and H2-blockade with cetirizine plus cimetidine caused a significantly greater reduction in induration than cetirizine (H1-blockade) alone; the reductions from the baseline value were 70%, 78%, 89%, 97%, and 33%, 53%, 43%, 30%, at times 0.25, 1, 6 and 24 h, respectively. The triple combination with the addition of betahistine (H1- and H2-agonist and H3-antagonist) resulted in reductions of 37%, 63%, 95% and 97% at the same times. The most striking changes in cellular dynamics were a significant increase in eosinophil (6 h) and neutrophil (6 h) vacuolation, and enhancement of monocyte (24 h) and basophil (6 h) accumulation, when the betahistine was added.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of metoclopramide, ondansetron and granisetron on aldosterone secretion in man

The plasma aldosterone response following the administration of drugs with antagonist and agonist activity at Serotonin 3 and 4 (5-HT3&4) receptors has been examined in 9 healthy male volunteers receiving the following four treatments i.v. in a randomised, cross-over sequence: ondansetron 8 mg, granisetron 3 mg, metoclopramide 20 mg, and saline 20 ml. Metoclopramide significantly increased the mean plasma aldosterone level to 196% of basal level at 5 min. It rose to 234% at 15 min and remained at more than 185% of basal level for the duration of the experiment. The response to ondansetron and granisetron did not differ significantly from placebo. If dopamine antagonism is discounted, the results suggest that metoclopramide-induced aldosterone secretion results from its agonist activity at 5-HT4 receptors, although slow neuronal depolarization via an unidentified receptor remains a possibility. Antagonism at the 5-HT3 receptor plays no role, as the selective antagonist, granisetron, did not elicit a significant response. It seems unlikely that the 5-HT4 receptor is the second, low affinity binding site of ondansetron, unless it had no agonist activity at this receptor.

Effects of diclofenac on isradipine pharmacokinetics and platelet aggregation in volunteers

In this open, two-period crossover study in 18 healthy male volunteers, a single oral dose of 50 mg diclofenac was administered alone and on day 7 of multiple oral dosing of 5 mg b.i.d. isradipine to assess a possible pharmacokinetic interaction. The effect of these drugs on ex vivo platelet function was also determined. Serial blood samples were obtained over 12-hour periods on three occasions: after the single diclofenac dose; after the morning dose of isradipine on day 6 and after co-administration of both drugs on day 7 of steady-state isradipine administration. Additional samples were taken at 2 h post dose for determination of ex vivo platelet aggregation. Isradipine plasma concentrations were determined by a gas chromatographic method and diclofenac plasma concentrations by an HPLC method. The pharmacokinetic characteristics of diclofenac were unaltered during co-administration. The maximum plasma concentration of isradipine was increased 19.6% during co-administration from 5.06 to 6.05 ng.ml-1. This is not expected to be of clinical importance. Isradipine's apparent total body clearance and steady-state AUC remained unchanged. Ex vivo induced platelet aggregation was not affected by any of the treatments.

A foreshortened method of measuring liquid gastric emptying in normal volunteers

The purpose of this study was to compare the cumulative fraction absorbed-time profile method of paracetamol with the shorter proportional area under the curve method of paracetamol by pretreating normal volunteers with cisapride, codeine and metoclopramide with and without neostigmine. Both methods are sensitive and comparable in defining early phase liquid gastric emptying, with the proportional area under the curve method having the advantage of providing the relevant information with a two-hour study period.

Effect of cetirizine, ketotifen and chlorpheniramine on the dynamics of the cutaneous hypersensitivity reaction: a comparative study

Allergic cutaneous challenge causes mast cell and basophil mediator release which recruit inflammatory cells to the site of antigen administration. This secondary cell infiltration and mediator release is responsible for the changes seen during the late phase of allergic diseases. In this randomised, double-blind, cross-over, placebo controlled study, it was demonstrated that, at steady-state drug concentrations, chlorpheniramine reduced the wheal-and-flare reaction by about 50% compared to the 75% reduction, on average, by cetirizine and ketotifen. Cetirizine significantly reduced eosinophil vacuolisation at all observation periods, i.e. 2,6,10 and 24 h, and also inhibited basophil accumulation significantly at 10 h (75% reduction), while chlorpheniramine had a negligible effect on these variables. These changes would indicate that the late phase reaction was modified, especially as eosinophil vacuolisation is known to correlate with late phase intensity, T-lymphocyte infiltration and subsequent tissue damage. It further supports previous speculation that cetirizine inhibit late histamine release by acting on basophils. The extent of induration in the late phase reaction did not differ significantly among the three treatments. Cetirizine and ketotifen, noticeably although not significantly, reduced eosinophil and lymphocyte recruitment. As these two antihistamines differ structurally and in regard to receptor specificity, it is possible that they exert their actions on other, unspecified, receptors.

Levamisole augments roxatidine's immune modulatory effects in the graft-versus-host reaction (GVHR)

Levamisole is known to have anti-anergic properties in immune compromised, but no or only marginal effects in immunologically competent subjects. In this study the possibility that levamisole would act as an 'immunoadjuvant' with roxatidine, a histamine H2 receptor blocker, is explored in healthy animals. Sixteen female, inbred Sprague-Dawley rats acted as lymphocyte donors and were treated for 8 days with either a roxatidine-levamisole combination, or levamisole alone, or roxatidine alone or placebo. Five randomly bred guinea pigs and eight inbred BD IX rats acted as lymphocyte acceptors. The in vivo effects of the four treatment modalities on transferred lymphocytes were expressed as the sizes of the allogeneic and xenogeneic graft-versus-host reactions as well as the radioactivity in each AGVHR. The combination of levamisole and roxatidine significantly augmented the cell mediated immune response in vivo and resulted in the most reactive lymphocytes as indicated by the AGVHR's and XGVHR's. These cells mediated reactions with significantly larger wheals as well as more lymphocyte proliferation in each reaction site than those caused by either levamisole or placebo treatment.

The effects of omeprazole-induced hypochlorhydria on absorption of theophylline from a sustained-release formulation

The present study was designed to investigate the effects of raised intragastric pH on the absorption of theophylline from a sustained-release formulation. Six healthy male volunteers participated in the cross-over randomised study and on one of two occasions were pretreated with 240 mg omeprazole, administered in three divided doses over the 22 h preceding the test. The sulphasalazine/sulphapyridine method of assessing oral-caecal transit time was implemented in order to assess upper bowel and colonic absorption. The mean fraction absorbed-time profile was calculated from serial serum theophylline concentration measurements by a modification of the Wagner-Nelson equation. During hypochlorhydria the mean oral-caecal transit time was 4.6 h, mean time to 90% absorption 6.8 h, and the percentage theophylline presumably to be absorbed from the colon 32.3. The corresponding values with normochlorhydria were, respectively, 3.8 h, 8.5 h, and 57.5%. The shorter oral-caecal transit time and lesser upper bowel absorption during normochlorhydria is postulated to result from motilin release due to duodenal acidification. Gastric hypoacidity resulted in significantly increased cumulative fractions of theophylline absorbed during a 3.5 h period, starting 0.5 h after breakfast. Possibly hypochlorhydria amplifies the increased motility which follows the intake of a meal, resulting in increased peristalsis and antiperistalsis, with more rapid drug absorption.

The influence of codeine, propantheline and metoclopramide on small bowel transit and theophylline absorption from a sustained-release formulation

1. The effects of the anticholinergic agent, propantheline, the opiate, codeine, and the prokinetic agent, metoclopramide, on oral-caecal transit time and on the absorption of theophylline from a sustained-release formulation were examined in six healthy male volunteers. 2. A cross-over randomised sequence design was followed, allowing at least 2 weeks interval between studies. On each occasion 500 mg theophylline in a sustained-release formulation was taken simultaneously with 2 g sulphasalazine at zero time. On three of the four occasions one of the following treatments was given concurrently at -0.5 h, +3.5 h, and +7.5 h: 30 mg codeine phosphate, 30 mg propantheline bromide, or 10 mg metoclopramide monohydrochloride. 3. The appearance of sulphapyridine in the plasma was used to assess oral-caecal transit time and the mean fraction absorbed-time profile of theophylline was calculated from serial serum theophylline concentration measurements using the Wagner-Nelson method. 4. Codeine increased the mean (s.d.) oral-caecal time (h) significantly (5.14 +/- 0.94) compared with the control value (3.78 +/- 0.34). Propantheline inhibited peristaltic contractions to such an extent that the oral-caecal transit time in five of the volunteers was between 9 and 25 h, while sulphapyridine appeared in the 9 h serum sample of the sixth. Metoclopramide did not significantly alter the oral-caecal transit time. 5. Despite the observed changes in oral-caecal transit time the rate and extent of theophylline absorption was similar with all regimens.

The absorption characteristics of six sustained-release theophylline preparations

Dosing intervals for sustained-release theophylline preparations depend on the rate of formulation absorption, the rate of elimination by the patient, and clinically acceptable fluctuations in serum concentration. A comparative study of intersubject variation in fraction absorbed-time profiles, a process-independent method of comparing rates of absorption, was performed with 6 sustained-release preparations in 6 healthy male volunteers. The sulphasalazine/sulphapyridine method of assessing orocaecal transit time was implemented so that upper gastrointestinal and colonic absorption could be estimated. Time until 90% absorption varied from 4.43 hours to 7.46 hours and the mean percentages of theophylline remaining to be absorbed from the colon were limited to between 7.5% and 29.7% with the various formulations. There was a great intersubject variability in the rate of theophylline absorption and also considerable differences among the volunteers in their formulation-to-formulation absorption profiles. Promotional literature depicting mean or group data masks this variability in absorption profiles. Because host factors related to gastro-intestinal physiology impose highly variable theophylline absorption profiles on sustained-release formulations, it is technically impossible to formulate a suitable once-a-day product for the majority of patients.

Effect of enalapril on allergen-induced cutaneous hypersensitivity reaction

1. To test the hypothesis that the in vivo inhibition of angiotensin converting enzyme in a patient who presents atopy, results in a significant increase in cutaneous bradykinin and prostaglandin production, the effect of enalapril on the cutaneous hypersensitivity reaction was examined in 10 atopic volunteers. 2. A crossover study design was used and volunteers were randomly allocated to treatment with either enalapril (10 mg) alone, or in combination with indomethacin (75 mg), with and without ketotifen (1 mg). Drugs were administered twice daily for 2 days. 3. Allergen (Southern Grass Mix) was administered intradermally 2 h after last drug dosage and the surface areas of the immediate wheal-and-flare-reactions were measured 15 min later. The late phase of the cutaneous response was evaluated 6 h later by determining skinfold thickness and surface area. 4. Enalapril alone had no effect on any of the parameters measured. 5. The cutaneous hypersensitivity reaction was significantly reduced with regard to both immediate and late cutaneous responses when the indomethacin and ketotifen combination was added to enalapril therapy. 6. When only indomethacin was added to enalapril pretreatment the flare reaction was significantly reduced, but whealing was unaffected. 7. This study presents further evidence that mast cell mediators other than prostaglandins are involved in the cutaneous hypersensitivity reaction. Furthermore, that endogenous bradykinin production after enalapril pretreatment either never reaches the supraphysiological concentrations used in previous experiments, or that bradykinin is rapidly and effectively broken down to inactive peptides by other carboxypeptidase enzymes.

In vivo augmentation of local xenogeneic graft-versus-host reaction by cimetidine and Bacillus Calmette-Guerin

Histamine-2 receptor blocker therapy (cimetidine) was combined with nonspecific Bacillus Calmette-Guerin (BCG) immunomoderation in order to obtain a more directed immunostimulatory response. To establish this the local xenogeneic graft-versus-host reaction (XGVHR) was used as objective in vivo parameter. In this placebo-controlled experiment the lymphocytes of inbred Sprague-Dawley rats were transferred intradermally to partially immunosuppressed guinea pigs after treatment with either or both of the test substances. The surface areas of the local XGVHRs were evaluated 48 and 72 h later. The local XGVHRs caused by lymphocytes obtained from rats treated with either cimetidine or BCG alone did not differ significantly from those caused by lymphocytes obtained from placebo-treated rats. Combination therapy, however, resulted in significant augmentation of the local XGVHR, clearly indicating a synergistic effect between cimetidine and BCG. The XGVHR appears to be a satisfactory model for evaluating drug effect on cell-mediated immune reaction in vivo.

Cimetidine as modulator of the cell-mediated immune response in vivo using the tuberculin skin test as parameter

The in vivo pharmacological effects of cimetidine on delayed hypersensitivity reactions in healthy volunteers were studied using the tuberculin skin test as parameter. Cimetidine clearly enhanced this reaction when it was administered well before antigenic stimulation.