Biomedical subjects
Publications and source records attributed to A A Belyĭ.
30 healthy 60- to 89-year-old subjects and 20 young ones (20 to 31 years) were given orally ammonium chloride 125 mg/kg. The signs of subsequent metabolic acidosis were more obvious in older subjects and they lasted longer. In young subjects, the intake of ammonium chloride induced a considerable hyperventilation.
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Renal function of 91 healthy subjects aged 18-91 has been evaluated at radionuclide renography with the use of 131I-Hippuran. Renal excretory function, effective renal plasma and blood flows were found to decrease annually by 0.09 ml/kg in ageing men and by 0.08 ml/kg in women. The use of new indices may be useful for evaluation of renal blood circulation, especially during hypo- or hypervolaemia is proposed. These are the index of renal circulation efficiency and the mean time of circulating blood volume transfer through renal blood vessels.
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Renin activity in blood plasma was studied by the radioimmune method in healthy persons and in hypertensive disease patients of various ages. It was found that this index diminishes with age in physiological ageing. The increase in the sensitivity of the ageing body to humoral agents, angiotensin among others, evidently compensates for the qualitative deficiency of the hormone. The results obtained provide evidence that the renal pressor mechanism is involved in the pathogenesis of late hypertensive disease at an earlier stage, which is probably due to the age preconditions, particularly the diminished intensity of intrarenal circulation, relative sympathicotonia at elderly and old age, and features of the electrolyte metabolism. The early activation of the renin--angiotensin system in the late stages of hypertensive disease should determine specified pathogenetic treatment of this disease in old age.
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Acetylsalicylic acid pharmacokinetics was studied in young, elderly and old patients after a single oral administration in a dose of 14 mg/kg. The pharmacokinetics data may be formalized by means of the one-compartment model with absorption. Constants of absorption and elimination, total clearance value are decreased with age. The half-life in elderly patients was 6.19 hrs, in old patients 12.2 hrs and in young patients 4.47 hrs. In elderly and old patients the area under the pharmacokinetic curve increased. The ability of serum proteins to bind salicylates reduced during ageing. The pharmacokinetic model was used for optimization of treatment with acetylsalicylic acid of elderly and old patients.
Nomograms for application of acetylsalicylic acid in persons of different age are presented. The nomograms are based on pharmacokinetic parameters of acetylsalicylic acid with regard to the age. Proceeding from the known constants of absorption and elimination, the nomograms are made use of to screen the loading and maintenance doses, to determine the time of administering the first maintenance dose and the maximal amount of the drug in the body, which was built up as a result of the use of the accepted treatment schedule. While using the nomograms one should be guided by the known therapeutic dose and the dosage intervals or by the therapeutic or maximal allowable dose. The nomograms are unsophisticated, fairly convenient, and help determine the optimal regimen of the use of acetylsalicylic acid in persons of different age.
Digoxin pharmacokinetics was studied in 40 virtually healthy subjects aged 60-89 years and 10 subjects aged 20-29 years injected with a single dose (0.5 mg) of digoxin. The pharmacokinetic data were interpreted in terms of a two-compartmental model. The constant of digoxin transfer rate from the peripheral compartment to the central one appreciably increased, whereas the elimination constant and the magnitude of the total clearance was decreased with aging. The values of the apparent volume of the drug distribution in the central compartment, as well as those of the stationary and kinetic volumes of distribution got reduced. In elderly and senile subjects, the pharmacokinetic curve area increased. The half-life of digoxin in young, elderly and senile subjects was equal to 51, 54 and 57 h, respectively.