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Choosing the right dose for beta-blocker treatment of hypertension: experience with tertatolol
Insights
Determining optimal antihypertensive drug dosage, including beta-blockers, requires extensive dose-response studies in early development. Phase I and II trials assess optimal dosing in volunteers and hypertensive patients, respectively, considering individual factors.
Area of Science:
- Pharmacology
- Clinical Trial Design
- Cardiovascular Medicine
Background:
- Optimal antihypertensive therapy dosage (unit dose and frequency) is under-discussed.
- Dose-effectiveness curves guide drug selection, necessitating broad dose testing during development.
Purpose of the Study:
- To outline the process for determining optimal beta-blocker dosage for antihypertensive therapy.
- To highlight the importance of dose-response studies in early drug development phases.
Main Methods:
- Phase I studies in healthy volunteers to assess optimal beta-blocking dose using isoprenaline and exercise tests.
- Phase II studies in hypertensive patients to refine dosage, considering factors like initial blood pressure.
- Evaluation of cross-over, parallel, and stepped-dose designs for clinical trials.
Main Results:
- Dose-response studies are crucial for identifying optimal drug doses.
- Phase I studies establish baseline optimal doses, while Phase II studies refine them for specific patient populations.
- Parallel and stepped-dose designs are often preferred over cross-over designs in hypertension studies due to practical and ethical considerations.
Conclusions:
- Systematic dose determination is essential for effective antihypertensive therapy.
- Clinical trial design must accommodate repeated drug administration and individual patient variability.
- Accurate blood pressure measurement techniques are fundamental for reliable study outcomes.
Abstract:
The determination of the optimum dosage for antihypertensive therapy, i.e. the unit dose and the administration frequency, remains one of the least discussed subjects. For beta-blockers as well as for other drugs, this determination is mainly based on the dose-effectiveness curve, the top of which corresponds to the right dose. Thus, a wide range of doses should be tested, and this as early as possible during drug development. The first step is to assess the optimum beta-blocking dose in healthy volunteers during phase I studies. These dose-response studies are usually performed according to a cross-over design. Among the many techniques proposed for assessing the effects of beta-blockers in man, isoprenaline and dynamic exercise tests are the most commonly used. The second step is to make use of the previous results to find the right dose for hypertensive patients in phase II studies. However, many individual factors which can influence the blood pressure response should be kept in mind, especially the initial blood pressure level. The choice of the design is generally based on the need to have repeated administration in order to obtain optimum control of the hypertension. Therefore, the cross-over design, although theoretically the best one, is rarely used on account of its practical and ethical problems. In contrast, the parallel design, with random assignment of treatments, is suitable to most experimental situations. Very different in nature, the stepped dose design stems from an ethical and practical approach of dose finding and thus is also widely used. Finally, correct measurement techniques of blood pressure are required.(ABSTRACT TRUNCATED AT 250 WORDS)