Age-Related Physiological Changes

Flavonoids can bind to plasma albumin,41 possibly decreasing their diffusion into cells.42 A 10% reduction of plasma albumin in older individuals43 44 could impact flavonoid distribution to tissues however, in fact, age-related decreases of albumin binding appear to have a minimal impact on the Vd of drugs 45 

Conversely, a prolonged GI transit could increase time for flavonoid absorption and metabolism. However, no studies have yet examined these relationships. 

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Placed in the context of response to drugs it is most useful to discuss age-related physiological changes... 

Taffet, G.E. Age-related physiologic changes. In Geriatric Review Syllabus A Core Curriculum in Geriatric Medicine, 3rd Ed Reuben, D.B., Yoshikawa, T.T., Besdine, R.W., Eds. Kendall/Hunt for the American Geriatric Society Dubuque, LA, 1996 11-24. 

While medications are probably the single most important factor in improving the quality of life for older Americans, the nation s seniors are especially at risk for medication-related problems due to age-related physiological changes, higher incidence of multiple chronic diseases and conditions, and greater consumption of prescription and over-the-counter medications. 

A number of age-related physiologic changes occur that potentially could affect drug pharmacokinetics and pharmacodynamics... 

Table 1. Important age- or pregnancy-related physiological changes which may alter drug kinetics ...

Nonetheless, there is evidence that oxidant stress contributes substantially to age-related physiological decline and pathological changes. Consequently, if it... 

Table 1 summarizes the physiological changes related to age or pregnancy. 

The prevalence of CHE increases and prognosis worsens with age. Some studies demonstrate that age markedly influences all follow-up events, including total mortality, and mortality or hospitalisation related to CHE. Some studies suggest that physiological changes occur in CHE with ageing with an age-related increase in systemic vascular resistance and circulating noradrenaline (norepinephrine) concentrations and a decrease in renal function. 

Age-related alterations in pharmacokinetics (absorption, distribution, metabolism, and excretion) have received considerable attention. Thus, physiological changes in elderly patients, when taken together, may contribute to impairments in drug clearance in this segment of the population (Table 6.5). 

McMahon TF, Medinsky MA, Bimbaum LS. 1994. Age-related changes in benzene disposition in male C57BL/6N mice described by a physiologically based pharmacokinetic model. Toxicol Lett 74(3) 241-253. 

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