PLASMA-LEVELS AND PHARMACOLOGICAL EFFECTS OF METOPROLOL ADMINISTERED AS CONTROLLED RELEASE (DURULES) AND ORDINARY TABLETS IN HEALTHY-VOLUNTEERS

  • 1 January 1980
    • journal article
    • research article
    • Vol. 18  (7) , 292-297
Abstract
The bioavailability, plasma levels and pharmacological effect of a daily dose of 0.2 g of the antihypertensive metoprolol in Durules and in regular 0.1 g tablets were studied in 8 healthy volunteers during steady state conditions. Durules and 2 0.1 g metoprolol tablets were given once daily, and 1 0.1 g metoprolol tablet was given every 12 h. The maximum concentration of metoprolol in plasma after Durules was .apprx. 1/2 of that after 2 regular tablets. When 1 metoprolol 0.1 g tablet was administered every 12th h, an average maximum concentration slightly higher than for the Durules was recorded .apprx. 1 h after the administration. The minimum concentration of metoprolol during the day was about twice as high after Durules as after the same dose in regular tablets. The dose-corrected area under the plasma concentration vs. time curve of Durules was 87% of the b.i.d. [twice daily] regimen of metoprolol in regular tablets and about 75% of 2 metoprolol 0.1 g tablets once daily. Metoprolol Durules maintained a more even effect on heart rate and systolic blood pressure during exercise during the day than the corresponding daily dose of metoprolol given as 2 metoprolol 0.1 g tablets once daily or as 1 metoprolol 0.1 g tablet every 12th h. After maximum .beta.-blockade the effect declined by, on average, 0.60% per h for the Durules and 0.96% for the regular tablet. The exercise heart rate before the morning dose was significantly lower during treatment with Durules and one metoprolol 0.1 g tablet b.i.d. than during the placebo period. The interaction of metoprolol with the effect of adrenaline [epinephrine] (0.09 .mu.g/kg per min, infused at 2, 3.5 and 5 h after metoprolol administration) on the diastolic blood pressure was more pronounced when 2 ordinary 0.1 g metoprolol tablets were administered once daily than for the corresponding dose in Durules, this probably reflecting a difference in degree of action of metoprolol on the vascular bed for Durules and regular metoprolol tablets in identical doses.

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