[Changes resulting from the implementation of the new EU Clinical Trial Regulation 536/2014 from the perspective of patients]

The currently valid Regulation (EU) 536/2014 on clinical trials with medicinal products for human use brings some innovations that are of great importance for patients who participate in clinical trials and patients with a need for innovative therapies. These concern patient protection, especially for vulnerable patient groups, as well as the conditions for further use of data obtained in clinical trials. The introduction of the largely publicly available information system CTIS (Clinical Trials Information System) will significantly improve the transparency of ongoing clinical trials. However, the possibilities of redacting commercially confidential information and postponing the publication of trial-related data and documents for several years may affect the scope of transparency. The request for the sponsor to provide a summary of the protocol and a summary of results of the clinical trial in layman's language (within one year after the end of the trial) also means a massive improvement in transparency for patients, even if this period seems too long, especially for patients with life-threatening diseases. Not all patient-relevant goals originally hoped for have been achieved. The systematic involvement of patients and patient organisations in the clinical trial protocol design is not required by the legislation enacted in 2014. The involvement of patients in the ethical review of the authorisation application dossier is only recommended in the introductory justification, but not codified in the law.

The New First-in-Human EMA Guideline: Disruptive or Constructive? Outcomes From the First EUFEMED Discussion Forum

The European Federation for Exploratory Medicines Development (EUFEMED) organized a meeting in Leuven, Belgium entitled ‘The new FIH EMA guideline: Disruptive or constructive?’ to provide a forum for stakeholders to discuss the guideline’s operational impact. The revised EMA Guideline on strategies to identify and mitigate risks for first-in-human (FIH) and early clinical trials with investigational products was published on 20 July 2017. The revision gave guidance on sentinel dosing/staggering of subjects within a multiple-ascending dose (MAD) clinical trial, permissible maximum exposure/investigation of supra-therapeutic doses and dose escalations above the no-observed adverse effect level. As the guidelines came into operation on 1 February, 2018 it was assumed that by the date of the meeting many early phase stakeholders had gathered sufficient first-hand experience of working within the guideline to discuss their thoughts on its impact. The concluding part of the meeting focused on the possible differences between European countries in handling the revised FIH guideline and ways of achieving harmonization. Information on current industry practice was gathered by online polling during the meeting, where perception of the revised guideline as either ‘disruptive’ or ‘constructive’ was explored at the start and at the end of the Forum along with recommendations on reducing future regulatory discordance. It was generally agreed that the necessary changes encompassed by new guidelines included both constructive and disruptive aspects. The final vote on whether the new FIH guideline is disruptive or constructive was taken by 69 delegates: 51% stated that it was both constructive and disruptive, 48% decided on constructive, none on disruptive and 1% were still undecided. It was generally accepted that stakeholders need to continue in a process of stakeholder engagement and discussion, particularly on critical safety issues. Such an approach allows partners to adopt a proactive approach to sharing best practice. For example, attendees agreed that a ‘Question and Answer’ document harmonized between the European agencies is required for the sentinel approach and for the selection of supratherapeutic doses.

EUFEMED London Conference 2017: Exploratory Medicines Development: Innovation and Risk Management

The first formal conference of the EUropean Federation for Exploratory MEdicines Development (EUFEMED) held in London was the result of a collaborative effort of its founding associations: the Association for Applied Human Pharmacology (AGAH; Germany), the Association for Human Pharmacology in the Pharmaceutical Industry (AHPPI; UK), the Belgian Association of Phase-I Units (BAPU; Belgium), and Club Phase-I (France). The conference focused on innovation and risk management in early clinical drug development. Among other innovations, immunotherapy in oncology and inflammatory diseases were discussed as well as the importance of adaptive trial designs in early clinical drug development. Consideration was given to assessing and mitigating risk in early clinical drug development, and included a preconference workshop. Different measures to minimize risks in healthy volunteers and patients in first-in-human trials were discussed in addition to the importance of non-clinical data, the need for reliable biomarkers, improved communication on adverse events (AEs) and well-trained study sites with ready access to intensive care units and clinical specialists. The need for a European-wide system for prevention of over-volunteering was also discussed. The conference provided opportunity to discuss these developments and concerns and the changing regulatory environment with stakeholders from academia, industry, and regulatory agencies including the European Medicines Agency (EMA). Presentations given by invited speakers are published on http://www.eufemed.eu/london-conference-2017/.

Pharmacokinetic and dynamic interactions of the angiotensin-converting enzyme inhibitor imidapril with hydrochlorothiazide, bisoprolol and nilvadipine

OBJECTIVE

The pharmacokinetic and dynamic interactions of the angiotensin-converting enzyme (ACE) inhibitor imidapril with other therapeutic principles used in hypertension and heart failure were evaluated.

METHODS

In three separate, double-blind, placebo-controlled, four-way cross-over studies in healthy volunteers (n = 16 each), single oral doses of imidapril 10 mg (I), hydrochlorothiazide 12.5 mg (H), bisoprolol 5 mg (B) and nilvadipine 8 mg (N) were administered as monotherapies, and in IH, IB and IN combinations. Plasma concentrations of imidaprilat and H were followed up to 48 h, those of B and N up to 24 h and area under the concentration time curve (AUC), maximum plasma concentration (Cmax) and time to Cmax (tmax) were determined. Blood pressure (BP), heart rate (HR) and non-invasive haemodynamics [total peripheral resistance (TPR, N and H), systolic time intervals (STI, N and H), and plasma renin activity (PRA)] were assessed up to 24 h.

RESULTS

There were no pharmacokinetic interactions between I plus H, B or N. Bioequivalence between single and combined administrations was verified for all investigational compounds [AUC point estimates (90% confidence interval CI): imidaprilat IH 109% (97.8, 122.8); IB 99.6% (91.2, 109.4); IN 105.7% (92.1, 121.3); H 96.6% (92.5, 100.8); B 103% (100.2, 105.8); N 98% (89, 108)]. The haemodynamic effects were mostly additive and without relevant pharmacodynamic interactions. I significantly reduced the BP by 5-8 mmHg, B by 4-8 mmHg and N by 4-6 mmHg. In addition, H induced a significant reduction of the preload as seen from STI, and B significantly reduced HR (-5 bpm). N induced a significant decrease in TPR (about 15% of baseline values) and showed corresponding changes in STI. PRA increased significantly following I alone (1.5-2.0 ng/ml/h), as well as combined with N (2.5 ng/ ml/h) or H (3.1 ng/ml/h). This increase was clearly blunted by the co-administration of B (0.6 ng/ml/h).

CONCLUSIONS

The combination of imidapril with a diuretic, beta-adrenoceptor antagonist or calcium-channel blocker seems a reasonable and safe treatment option when striving for additive pharmacodynamic effects not accompanied by relevant pharmacokinetic interactions.

Treatment of congestive heart failure--current status of use of digitoxin

Digitalis glycosides exert a positive inotropic effect, i.e. an increase in myocardial contractility associated with a prolongation of relaxation period, and glycosides lower the heart rate (negative chronotropic), impede stimulus conduction (negative dromotropic) and promote myocardial excitability (positive bathmotropic). They seem to influence the activities of both the vagal and the sympathetic systems. Digitalis glycosides that belong to different substance classes are closely comparable concerning pharmacodynamics but differ substantially in regard to pharmacokinetics. Digoxin and its derivatives are less lipophilic, show lower protein binding and shorter half-life, are mainly eliminated via the kidney and accumulate rather rapidly in cases of insufficient kidney function. Digitoxin is highly lipophilic and extensively bound to plasma proteins, has a longer half-life, is mainly eliminated in the metabolized state via urine and faeces and does not accumulate in kidney dysfunction. As a result of a more stable pharmacokinetic profile, the incidence of toxic side effects seems to be lower with digitoxin than with digoxin. Since the beginning of the 1990s, the antagonists of the RAAS qualified as the standard treatment for congestive heart failure, often in combination with diuretics, vasodilators or beta-antagonists. However, the important role of digitalis glycosides as therapeutic comedication or alternative was never denied, especially in atrial fibrillation with tachycardia. The PROVED and RADIANCE trials proved a detrimental effect of the withdrawal of digoxin therapy on exercise capacity, left-ventricular ejection fraction and clinical symptoms. The DIG trial revealed that digoxin comedication in sinus rhythm patients with congestive heart failure was associated with a lower morbidity (as taken from death or hospitalization because of worsening heart failure) and an unchanged overall mortality--being a unique feature among the available inotropic drugs. Comparable studies for digitoxin have not yet been performed but, because of its higher pharmacological stability, it might well be associated with even more advantages in this regard than digoxin.

The pharmacological potency of various AT(1) antagonists assessed by Schild regression technique in man

RATIONALE

A quantitative technique was used to compare the pharmacological potency in healthy volunteers of angiotensin II receptor antagonists (AIIA): candesartan cilexetil, losartan, irbesartan, valsartan, and telmisartan.

METHODS

In a randomised, double-blind, parallel-group (4x12 subjects) study, single oral doses of candesartan cilexetil 4, 8 and 16 mg, losartan potassium 25, 50 and 100 mg, valsartan 40, 80 and 160 mg, and irbesartan 75, 150 and 300 mg were administered on three consecutive days. Telmisartan 20, 40 and 80 mg was similarly evaluated in 12 volunteers in an open amendment. Angiotensin II (Ang II) antagonistic effects were determined in vivo from rightward shifts in Ang II dose-response curves for diastolic blood pressure (BP) and dose ratios were calculated. Apparent K(i)-doses, i.e. doses (in mg) required to induce a two-fold shift in Ang II dose-response curves (equivalent to approx. 50% blockade of receptors) were determined, using Schild regression analysis.

RESULTS

All treatments dose-dependently attenuated increases in diastolic BP induced by infusion of exogenous Ang II. Candesartan cilexetil appeared to have a more pronounced increase in effect following cumulative dosing. At 24 hours, apparent K(i)-doses were: candesartan cilexetil 6 mg, irbesartan 123 mg, valsartan 93.5 mg, and telmisartan 54 mg. It was not possible to determine an apparent K(i)-dose for losartan at 24 hours.

CONCLUSION

Consistent with results from experimental pharmacology, candesartan cilexetil displayed the highest pharmacological potency (i.e. antagonistic activity per mg substance) of the AIIAs tested. Apparent K(i)-doses at 24 hours were within the dose range recommended for clinical use in patients with hypertension.

Comparative pharmacodynamics and pharmacokinetics of candesartan and losartan in man

The angiotensin II antagonistic effects of candesartan and losartan were compared in-vivo after single and repeated doses. Effects were related to antagonistic activity in plasma. In this double-blind, crossover study, 12 healthy male volunteers received, in random order, daily oral doses of 8 mg candesartan cilexetil or 50 mg losartan for seven days. On day 1 and day 8, dynamics and kinetics were assessed up to 48 h after dosing. Antagonistic effect was determined from the antagonist-induced rightward shifts of the diastolic blood pressure response curves to exogenously administered angiotensin II measured as the dose ratio (DR). The antagonistic activity in plasma was measured using an ex-vivo/in-vitro radioreceptor assay. Specific high-performance liquid chromatography assays determined plasma concentrations of candesartan, losartan and its active metabolite EXP-3174. The pharmacokinetic properties of candesartan and losartan were comparable and antagonistic activity in plasma almost identical (ratio candesartan: losartan = 0.97 and 1-2 after single and multiple doses, respectively). However, the antagonistic effects of candesartan and losartan in-vivo were quite different. Twenty-four hours after single dosing with candesartan a clinically relevant rightward shift in the angiotensin II dose-response curve (DR= 3.2) occurred that was more pronounced than that following losartan administration (DR=2.1, ratio candesartan: losartan= 1.65). Twenty-four hours after multiple doses of candesartan or losartan, the values of the DR were 4.8 and 2.3, respectively (ratio candesartan: losartan = 1.94). The values of DR for candesartan were significantly higher compared with losartan between 6 and 36h after a single dose and between 3 and 24 h post-dose following multiple dose administration. A counter-clockwise hysteresis was apparent between antagonistic activity in plasma and antagonistic effect. Despite equivalent angiotensin II antagonistic activity in plasma, the pharmacodynamic effect of candesartan cilexetil was greater than that of losartan. Candesartan appeared to have a slower off-rate from the angiotensin AT1-receptor compared with losartan, nevertheless differences in distributional phenomena or the extent of insurmountable antagonistic activity cannot be ruled out.

Epidemiology of the arterial stiffness

Aortic stiffening is as much an important risk factor in cardiovascular morbidity and mortality, as it serves as reliable surrogate marker for clinical endpoints like myocardial and cerebrovascular incidents. Elevated aortic stiffness induces high systolic blood pressure, augmented pulse pressure with increased ventricular afterload, reduced subendocardial blood flow and augmented pulsatile stress in the peripheral arteries. Factors with relevant impact on the epidemiology of arterial stiffness are widely spread. 3 major groups of parameters influencing the stiffness of the aorta and the large arteries have been studied and described up to now: (i) physiological properties like age, gender, body height, pressure, hormonal state, genetic factors; (ii) environmental factors like nutrition (fish-, salt-, garlic consumption), smoking, performance of sports and aerobic capacity; (iii) diseases like hypertension, hypercholesterolemia, diabetes, coronary heart disease, cerebrovascular disease, renal failure, Marfan-syndrome, growth hormone deficiency. Close association between several of these factors impedes analyzing them independently from each other. Age and blood pressure were found to be the most prominent predictors of arterial stiffness in normal as well as in disease populations. Physiological and environmental factors can modulate these effects of aging, diseases generally seem to amplify them.

Dose-proportionality of oral thioctic acid--coincidence of assessments via pooled plasma and individual data

Thioctic acid (TA), a racemate of R-(+)- and S-(-)-enantiomers of alpha-lipoic acid, acts as a powerful lipophilic, free-radical scavenger and is used in the treatment of diabetic neuropathy. This trial investigated the dose-linearity of enantiomer pharmacokinetics following the oral administration of single doses of 50 to 600 mg TA (formulation provided by ASTA (Medica)) in healthy volunteers. TA enantiomer concentrations in individual and pooled plasma samples were determined using enantioselective, high-performance liquid chromatography. TA was rapidly absorbed (tmax, 0.5 to 1 h). Maximum plasma concentrations (Cmax) of the R-(+)-enantiomer were about 40-50% higher than those of the S-(-)-enantiomer (50 mg: 135.45 ng/ml R-(+)-TA, 67.83 ng/ml S-(-)-TA; 600 mg: 1812.32 ng/ml R-(+)-TA, 978.20 ng/ml S-(-)-TA; geometric means). The decline observed in the plasma concentration was steep (t1/2, 0.5 h). The dose-linearity and proportionality of pharmacokinetic parameters could be demonstrated on an intra-individual basis and for the group geometric means. An analysis of pooled plasma samples proved to be a suitable means for deriving reliable first-sight results prior to individual assessments.

Blood pressure and aortic elastic properties--verapamil SR/trandolapril compared to a metoprolol/hydrochlorothiazide combination therapy

The effects of 2 fixed antihypertensive combination drugs on blood pressure and aortic elastic properties were compared in 2 parallel groups. Twenty-six patients for 6 months received a calcium antagonist plus ACE inhibitor (verapamil SR 180 mg/trandolapril 1 mg (Vera/Tran)) and 25 patients a beta-adrenoceptor antagonist plus diuretic (metoprolol 100 mg/hydrochlorothiazide 12.5 mg (Meto/HCTZ)). In addition to blood pressure (SBP, DBP), carotidofemoral pulse wave velocity (PWV) was assessed non-invasively. Total peripheral resistance (TPR) was determined from cardiac output derived by electrical impedance cardiography. Sitting DBP decreased for -14.4 mmHg following Vera/Tran compared with -9.2 mmHg following Meto/HCTZ (p = 0.02 for difference between treatments). Blood pressure was normalized (i.e. DBP < 90 mmHg) in 69% of patients with Vera/Tran and in 52% with Meto/HCTZ. PWV was lowered with Vera/Tran to a higher extent than with Meto/HCTZ (differences between group means -0.46 to -0.98 m/sec, statistically not significant). Vera/Tran induced a decrease in TPR of about 15% of baseline values, whereas Meto/HCTZ showed no influence. Treatment-related adverse events following Meto/HCTZ were bradycardia and associated symptoms; following Vera/Tran these were cough and edema in 1 case each. In the Meto/HCTZ group, there were more withdrawals/drop-outs (9/25) than in the Vera/Tran group (2/26). The somewhat more intense reduction in PWV with Vera/Tran is indicative of an increase in aortic elastic properties associated with the more potent decrease in BP. In the present study, the combination of calcium antagonist plus ACE inhibitor was found to be an effective and well tolerated antihypertensive regimen and in these respects appears to have some advantages compared with a combination of beta-blocker plus diuretic.

Angiotensin II antagonism and plasma radioreceptor-kinetics of candesartan in man

AIMS

The pharmacodynamic properties of the angiotensin II antagonist candesartan in humans were assessed from the rightward shifts of angiotensin II dose-effect curves (Schild regression technique). The pharmacokinetic characteristics were determined by radioreceptor assay (r.r.a.) and h.p.l.c.

METHODS

Twelve healthy male volunteers received single oral doses of 4, 8 and 16 mg candesartan cilexetil and placebo. Plasma was obtained for h.p.l.c. and r.r.a. (receptors: rat lung; radioligand: [125I-Sar1Ile8]-angiotensin II). Before and up to 24 h post dosing angiotensin II was infused in ascending dose steps until blood pressure (systolic and/or diastolic) increased by +25 mmHg. Individual angiotensin II dose-effect curves were fitted according to an Emax model and dose ratios (DR) calculated from the antagonist induced rightward shifts.

RESULTS

Candesartan, the active metabolite of candesartan cilexetil, declined from peak concentrations at about 4 h with a t1/2 of about 6 h. A linear relation (slope 1) between h.p.l.c. and r.r.a. data revealed that there is no other active metabolite. DR at 6-9 h post dosing reached a maximum of about 30 and at 24 h still amounted to 4-7, indicating the persistence of a relevant antagonistic effect in vivo. The apparent Ki-doses (derived from Schild regression plots) indicated a high potency (1.9 mg at 24 h) and slow decline of effect. Between plasma concentrations and antagonistic effect a counterclockwise hysteresis was visible.

CONCLUSIONS

A longer persistence of the antagonistic effect at the receptor site than expected by the presence in plasma indicates a slow off-rate of candesartan cilexetil from in vivo receptors. This provides an additional rationale for the observed 24 h therapeutic activity of candesartan cilexetil.

Adverse events and discomfort in studies on healthy subjects: the volunteer's perspective. A survey conducted by the German Association for Applied Human Pharmacology

OBJECTIVE

The various good clinical practice (GCP) guidelines do not define the volunteering subject as an active party. The present survey addresses the volunteer's perception of study-related inconvenience and risk and its impact on their decision to enroll.

METHODS

The survey consisted of a questionnaire to be filled out voluntarily and anonymously by healthy subjects who volunteered for enrollment in human pharmacology studies and who had participated in at least one previous study. Twenty-five categorised multiple-choice questions covered previous study experience, motives for volunteering, perception of and compliance with study directives and restrictions, past experience with adverse events, impact of the study environment on perceived well-being and the nature of adverse events likely to discourage them from enrollment.

RESULTS

Seven centres contributed by providing at least 30 (range 30-100) evaluable questionnaires. The database consists of a total of 440 healthy subjects (30.5% females, 69.5% males), from 18 to over 60 years of age. Two hundred and seven subjects (47.1%) were company employees and 233 (52.9%) were external volunteers. Eighty nine percent only participated in studies at one particular centre. Some 53.3% indicated financial motives, 27.8% 'contribution to an improvement of pharmacotherapy', 12.7% 'social responsibility', while 6.2% indicated other motives, mainly the opportunity of a free medical check-up. Thirteen subjects (3%) admitted to not answering correctly to the recruitment questions; this limited reliability is suspected to be even larger when the answer might preclude enrollment. From the volunteers' perspective, the environmental study conditions clearly appeared to have a highly relevant impact on their personal well-being. Some 17.1% of the subjects reported to have suffered adverse events occasionally and 2.7% frequently; but 14% admitted not reporting adverse events promptly and about 20% indicated that, with respect to previous adverse events, they first sought advice from other volunteers rather than from the investigator.

CONCLUSIONS

Adverse events and inconveniences are inherent to nontherapeutic studies in healthy subjects. From the volunteer's perspective it appears that the incidence of adverse experiences in such studies exceeds the reported frequencies from investigators considerably. This finding suggests that investigators are usually not aware or able to ascertain the true incidence of adverse events. The present survey also confirms that pertinent information on the personal history may be unreliable. Volunteers are reluctant to answer questions regarding, in particular, their smoking habits, caffeine and alcohol consumption. Regarding the matter of informed consent, a noteworthy contradiction between the volunteers' attitude and behaviour became apparent. Although the volunteers admit that even rather minor adverse events ordinarily would discourage them, they still consent to enrollment. In view of this apparent contradiction, there is no alternative to the investigator's personal responsibility to counsel and protect the subject. Surveys such as this one may contribute to the awareness that the explicitness of GCP guidelines merely define the format, but not the content quality of these fundamental ethical values, which remain the unique burden and challenge of the investigator.

Protective effect of chronic garlic intake on elastic properties of aorta in the elderly

BACKGROUND

Epidemiological studies have suggested that garlic may have protective effects against cardiovascular diseases. We undertook this cross-sectional observational study to test the hypothesis that regular garlic intake would delay the stiffening of the aorta relating to aging.

METHODS AND RESULTS

We studied healthy adults (n=101; age, 50 to 80 years) who were taking > or = 300 mg/d of standardized garlic powder for > or = 2 years and 101 age- and sex-matched control subjects. Pulse wave velocity (PWV) and pressure-standardized elastic vascular resistance (EVR) were used to measure the elastic properties of the aorta. Blood pressures, heart rate, and plasma lipid levels were similar in the two groups. PWV (8.3+/-1.46 versus 9.8+/-2.45 m/s; P<.0001) and EVR (0.63+/-0.21 versus 0.9+/-0.44 m2 x s(-2) x mm Hg(-1); P<.0001) were lower in the garlic group than in the control group. PWV showed significant positive correlation with age (garlic group, r=.44; control group, r=.52) and systolic blood pressure (SBP) (garlic group, r=.48; control group, r=.54). With any degree of increase in age or SBP, PWV increased less in the garlic group than in the control group (P<.0001). ANCOVA and multiple regression analyses demonstrated that age and SBP were the most important determinants of PWV and that the effect of garlic on PWV was independent of confounding factors.

CONCLUSIONS

Chronic garlic powder intake attenuated age-related increases in aortic stiffness. These data strongly support the hypothesis that garlic intake had a protective effect on the elastic properties of the aorta related to aging in humans.

Pharmacodynamic and pharmacokinetic properties of an angiotensin II receptor antagonist--characterization by use of Schild regression technique in man

OBJECTIVE

The pharmacodynamic properties of a new angiotensin II receptor antagonist (BAY 10-6734) in humans were to be quantitatively characterized from the rightward shifts of the agonist dose-response curves after administration of different doses of the antagonist.

METHODS

24 healthy male volunteers received single oral doses of 20-300 mg BAY 10-6734. Before and up to 23 h post dosing (p.d.) plasma was obtained for HPLC measurement of parent compound and active metabolite BAY 10-6735. Exogenous angiotensin II was infused in increasing dose steps until blood pressure had increased by +25 mmHg. Angiotensin II dose-response curves were fitted individually using the sigmoidal Emax model. From the antagonist-induced rightward shifts, as compared to a premedication curve, dose ratios (DR) were determined and DR-1 plotted versus applied dosages and measured plasma concentrations. From these Schild regression plots the fictive doses and concentration (Ki) inducing a DR-1 = 1, i.e. a 2-fold shift in agonist dose-response curves, were derived. The "doubling (t2.0) time" of the apparent Ki doses was calculated.

RESULTS

BAY 10-6734 dose-dependently induced rightward shifts of the angiotensin II blood pressure response curves, mean maximum DR at 2 h p.d. ranged from 42 (80 mg) to 216 (300 mg), and at 23 h p.d. decreased to about 2 (80 mg) to 4 (300 mg). Pharmacodynamic (3.4-4.6 h) and pharmacokinetic half-lives (3.4-4.3 h) were nearly identical. Apparent Ki doses increased from about 1-2 mg at 2 h p.d. to about 80-100 mg at 23 h p.d., their time course revealed a doubling (t2.0) time of 3.5-3.8 h. A Ki concentration of about 10 micrograms/l was obtained for the active metabolite BAY 10-6735.

CONCLUSIONS

Oral administration of BAY 10-6734 in man antagonized angiotensin II dose blood pressure response curves in a dose-dependent manner. The time kinetics of the pharmacodynamic effect, derived from the decay of DR-1 values, as well as the doubling time of the apparent Ki values well agreed with the pharmacokinetic half-life. Schild regression revealed competitive angiotensin II antagonistic properties within the dose/concentration range tested. This technique was shown to be an adequate means to evaluate pharmacodynamic potency and kinetic behavior of an angiotensin II receptor antagonist in vivo.

Influence of antihypertensive therapy with cilazapril and hydrochlorothiazide on the stiffness of the aorta

The purpose of this study was to examine the effects of the angiotensin-converting enzyme (ACE) inhibitor cilazapril on the elastic properties of the aorta. A standard diuretic antihypertensive drug, hydrochlorothiazide, served for comparisons. Increased aortic stiffness leads to a reduction of the buffering windkessel function and is a major component in the pathophysiology of systolic hypertension, inducing an increase in left ventricular afterload and arterial pulsatile stress as well as a decrease in the subendocardial blood supply. Stiffness of arteries increases with age and blood pressure, and depends on the functional elastic structures of the aortic wall. ACE inhibitors have been shown to directly influence elastic properties of peripheral arteries. Seventeen patients with mild to moderate essential hypertension (age 45-67 years) were treated for 3 months double-blind randomized with either cilazapril (C) 5 mg daily (n = 9) or hydrochlorothiazide (HCTZ) 25 mg daily (n = 8). Aortic elastic properties were noninvasively assessed by measurement of pulse wave velocity along the aorta at rest and during isometric handgrip stress. Accelerated pulse wave velocity indicates elevated arterial stiffness and vice versa. A pressure standardized index of aortic cross-sectional distensibility (2 m) was calculated from arterial mean pressure and pulse wave velocity. Compared with pretreatment values, both therapies significantly reduced blood pressure and pulse wave velocity at rest (C: 9.4 +/- 0.9 vs. 7.7 +/- 0.7 m/sec; HcTZ: 8.9 +/- 0.3 vs. 7.8 +/- 0.4 m/sec; means +/- SEM p < 0.05). During isometric stress only C showed a significant decrease in pulse wave velocity (C: 11.3 +/- 0.8 vs. 9.1 +/- 0.8 m/sec; HCTZ: 9.9 +/- 0.5 vs. 9.0 +/- 0.5 m/sec; means +/- SEM p < 0.05). The index 2m at rest and during handgrip increased significantly (p < 0.05) after C but not after HCTZ. With cilazapril we obtained steeper slopes for the treatment-induced reductions in blood pressure and pulse wave velocity for both rest and handgrip stress values. Correlation of the data at rest and during stress revealed a direct relationship between blood pressure and pulse wave velocity. HCTZ linearly extended the relation observed before treatment toward lower values of blood pressure and corresponding pulse wave velocity without changing the relation per se. Cilazapril, in contrast, moved the relation between these variables and decelerated the pulse wave velocities to a greater extent than would have been expected from the corresponding blood pressure reduction (delta approximately 1 m/sec). These results in patients with mild to moderate essential hypertension support the idea that ACE inhibitors, in addition to reducing blood pressure, may exert an additional hemodynamic effect in improving the elastic properties of the aorta.

Reproducibility and consistency of the responses to supine bicycle ergometry; evaluation in conjunction with beta 1-adrenoceptor occupancies

A protocol is presented for supine bicycle ergometry in healthy subjects, which aims for a target increase of heart rate (HR = 140 beats min-1) after 4 min cycling under constant load. The required load is selected from a pre-study ergometry with stepwise increasing load. Repeated testing with this protocol was shown to yield highly reproducible ergometric HR-responses. Because of their high reliability, the ergometric endpoints and increments permit a highly sensitive comparison of beta 1-adrenoceptor antagonism across dose and time within a given compound. The relationship between the changes of the ergometric rise of HR and the beta 1-adrenoceptor occupancy (estimated from radioreceptor assay data) permits to evaluate the ergometric efficiency of different beta-adrenoceptor antagonists across time and doses and to identify eventual differences that do not relate primarily to the extent of beta 1-adrenoceptor antagonism itself.