Pharmacology and aging

Behavioral Reactions to Psychotropic Medication Changes for Nursing Home Residents Receiving Psychogeriatric Programming

Initiation of programming for mentally ill nursing home residents made it possible to examine the effect of changes in psychoactive medications on their behavior. These changes in psychotropics were a central aspect of the medication management component of a psychogeriatric rehabilitative program. Despite the nationwide debate concerning the use of medications in controlling nursing home residents, some staff members criticized medication reductions as leading to psychiatric instability. Compared to 34 residents of a "waiting list" nursing home, 99 residents at three facthties with psychogeriatric programming did receive many more changes in medicattons, especially reductions. But these medication decreases were not associated with more behavioral problems during the 31-week observation period. Behavioral difficulties were measured by a weighted sum of restraint usage, incident reports, and pro re nata (PRN) medications. Simplified time-series analysis (STSA) indicated that behavioral difficulties had been mounting prior to increases in medications, decreases in medications, and changes in drug category. Although there was a temporary rise in behavioral problems for 2 weeks after medication decreases, behavioral difficulties were reduced within 8 weeks of all types of drug changes. This article compares the observed jump in behavioral difficulties to "extinction bursts" and discusses the relationship between rehabilitative programming, staff consistency, and psychotropic adjustments.

Identifying an indoor air exposure limit for formaldehyde considering both irritation and cancer hazards

Formaldehyde is a well-studied chemical and effects from inhalation exposures have been extensively characterized in numerous controlled studies with human volunteers, including asthmatics and other sensitive individuals, which provide a rich database on exposure concentrations that can reliably produce the symptoms of sensory irritation. Although individuals can differ in their sensitivity to odor and eye irritation, the majority of authoritative reviews of the formaldehyde literature have concluded that an air concentration of 0.3 ppm will provide protection from eye irritation for virtually everyone. A weight of evidence-based formaldehyde exposure limit of 0.1 ppm (100 ppb) is recommended as an indoor air level for all individuals for odor detection and sensory irritation. It has recently been suggested by the International Agency for Research on Cancer (IARC), the National Toxicology Program (NTP), and the US Environmental Protection Agency (US EPA) that formaldehyde is causally associated with nasopharyngeal cancer (NPC) and leukemia. This has led US EPA to conclude that irritation is not the most sensitive toxic endpoint and that carcinogenicity should dictate how to establish exposure limits for formaldehyde. In this review, a number of lines of reasoning and substantial scientific evidence are described and discussed, which leads to a conclusion that neither point of contact nor systemic effects of any type, including NPC or leukemia, are causally associated with exposure to formaldehyde. This conclusion supports the view that the equivocal epidemiology studies that suggest otherwise are almost certainly flawed by identified or yet to be unidentified confounding variables. Thus, this assessment concludes that a formaldehyde indoor air limit of 0.1 ppm should protect even particularly susceptible individuals from both irritation effects and any potential cancer hazard.

Effect of age on in vitro triazolam biotransformation in male human liver microsomes

We studied age-related changes in enzyme kinetic parameters in human liver microsomes (HLMs) in vitro, using triazolam (TRZ), an index of CYP3A activity. HLMs were prepared from male livers from four age groups, n = 5 per group: A (14-20 years), B (21-40 years), C (41-60 years), and D (61-72 years). Mean V(max) values in groups B and C for both 1-hydroxytriazolam (1-OH-TRZ) and 4-hydroxy-triazolam (4-OH-TRZ) formation were significantly greater as compared with groups A and D individually, as well as the net intrinsic clearance (sum of the two pathways). The mean net intrinsic clearance (Cl(int)) values were 25.2, 89.8, 78, and 20.6 nl/min/mg protein in A, B, C, and D, respectively. TRZ Cl(int) correlated well with total CYP3A content (r(s) = 0.84; P < 0.0001). Testosterone (TST) inhibited 1-OH-TRZ formation and activated 4-OH-TRZ formation in all age groups, with no significant differences among the groups; this suggests that the drug-drug interaction potential using TRZ and TST as index CYP3A substrates may not change with age. Reduced V(max) and Cl(int) for TRZ hydroxylation and CYP3A protein in livers from elderly men suggest reduced CYP3A gene expression in this group.

Composition and cost of drugs stored at home by elderly patients

BACKGROUND

Elderly people often have multiple chronic diseases, are frequently treated by several physicians, and also use over-the-counter medications. Excessive prescribing, imperfect therapeutic adherence, treatment modifications after hospitalization, and oversized drug packages result in home storage of leftover drugs, resulting in a waste of healthcare resources.

PATIENTS AND METHODS

All patients aged >/=75 years hospitalized for >24 hours during a 6-month period in an urban teaching hospital in Switzerland were eligible for inclusion in a study collecting sociodemographics, medical, functional, and psychosocial characteristics. Six months later, a research nurse visited the patients at home and recorded the names, number of tablets, and expiration dates of all open or intact drug packages, and the doses actually taken. Acquisition costs of these drugs were computed.

RESULTS

One hundred ninety-five patients were included (127 women; mean age 82.2 +/- 4.8 y, range 75-96). They had a total of 2059 drugs (mean per patient 10.3 +/- 6.7, range per patient 1-42), corresponding to a total cost of (US) $62 826 (mean per patient 322 +/- 275, range per patient 10-1571). Self-reported drug intake was regular for 36% of the drugs (46.5% of total costs) and occasional for 11% (6.1%), whereas 35.7% (30.1%) had been stopped during the last month. Cardiovascular drugs amounted to 36.6% of the drugs and 55.5% of the costs. None of the patients' characteristics was significantly associated with a greater number of drugs and higher costs.

CONCLUSIONS

Drugs stored at home by elderly patients were worth about $320 per patient. Only about one-third of these drugs were regularly taken. In the context of resources shortage, innovative solutions should be found to reduce the waste linked with drugs stopped in previous months.

The influence of age and some inducers on UDP-glucuronyltransferase activity

UDP-glucuronyltransferase (UDP-GT) activity was examined in male Wistar rats aged 0.5, 1, 2, 4, 8, 12, 20, and 28 months. The rats were treated with phenobarbital (75 mg/kg, 72 and 48 h before death), beta-naphthoflavone or dexamethasone (40 mg/kg and 20 mg/kg, respectively, for three days before death). Prior to decapitation the rats were fasted for 12 h. Hepatic microsomes were prepared according to the method of Dallner. UDP-GT activity was determined by the method of Burchell and Weatherill. p-Nitrophenol was used as an aglucone. UDP-GT activity decreased rapidly in the control rats aged from two weeks to four months. In the older control rats the activity tended to increase. Two-week-old rats treated with phenobarbital showed a slightly increased UDP-GT activity. In the older animals (up to one year) UDP-GT activity increased to 150% of the control value and stayed at this level in the remaining age groups. beta-Naphthoflavone was a more potent inducer of UDP-GT than phenobarbital. The activity of beta-naphthoflavone-induced UDP-GT was low in the youngest rats. It was about 180% in two-month-old rats and reached 260% of the control value in eight-month-old rats. Although the activity decreased in the older rats, it still exceeded 200%. Dexamethasone did not affect UDP-GT activity. Only in two-week-old and two-month-old rats did we observe a slight increase in the activity of UDP-GT.

Effect of age and gender on the activity of human hepatic CYP3A

Many pharmacokinetic investigations in the elderly population reveal decreased clearance of lipophilic drugs metabolized by the cytochrome P450 enzymes; however, few studies have evaluated aging-dependent or gender-related changes in specific cytochrome P450 enzymes. The clearance of quinidine, midazolam, triazolam, erythromycin, and lidocaine declines with age; these drugs are metabolized by the isoform, CYP3A. To determine whether these metabolic effects are due to changes in CYP3A, the effects of age and gender on CYP3A activity were examined. The activity of the human hepatic cytochrome P450, CYP3A, was quantified in vitro as erythromycin N-demethylation in microsomes prepared from forty-three resected human liver specimens obtained from patients, age 27 to 83, with normal liver function. Erythromycin N-demethylation varied 5-fold in human liver microsomes. CYP3A activity was 24% higher in females than males (P = 0.027). CYP3A activity did not correlate with age, smoking status, ethanol consumption or percent ideal body weight. Large interindividual differences and a small female-specific increase in CYP3A activity were obtained. However, CYP3A activity was unaffected by age over the range of 27-83 years, suggesting that the aging-related alteration in the clearance of CYP3A substrates is secondary to changes in liver blood flow, size, or drug binding and distribution with aging.

Ventilatory effects of subarachnoid fentanyl in the elderly

Twenty-eight elderly patients scheduled for urological surgery were randomly assigned to receive, in a double-blind study, subarachnoid hyperbaric bupivacaine 15 mg with 50 micrograms (group A, n = 7), 25 micrograms (group B, n = 7), or 12.5 micrograms (group C, n = 7) of fentanyl or 1 ml of saline (group D, n = 7) in a total volume of 4 ml. The pattern of breathing and the ventilatory response to CO2 were studied before and 90, 150 and 480 min after the subarachnoid injection. In group A, mild pruritus and sedation occurred in five patients, while nausea, vomiting and periodic breathing occurred in two. In group B, mild pruritus and sedation were observed in four patients, while nausea and vomiting occurred in two. No significant differences in minute ventilation, respiratory drive and respiratory timing were observed between the groups. Patients receiving fentanyl 50 micrograms showed a percentual change from baseline values as function of time (slope VE/PE'CO2) significantly below baseline at 90 and 150 min (p less than 0.05). However, the baseline values in this group reverted after 480 min. No side effects were observed in groups C or D. It is concluded that subarachnoid fentanyl 50 micrograms can cause an early respiratory depression and its use as a postoperative analgesic should be avoided in the elderly.

Hepatic cytochrome P-4503A (CYP3A) activity in the elderly

Elderly patients exhibit decreased clearance of multiple drugs biotransformed by the hepatic cytochromes P-450. The cytochromes P-450 are a superfamily of enzymes, which comprise a central component of phase I drug metabolism. Distinct isoforms metabolize specific drugs. In human liver microsomes, the glucocorticoid-inducible cytochrome P-450IIIA, CYP3A, catalyzes the N-demethylation of erythromycin. To examine the activity of hepatic CYP3A in elderly males and females, erythromycin N-demethylation was examined, as reflected by the recently described [14C]erythromycin breath test in 24 healthy volunteers, age 70-88. The [14C]erythromycin breath test was measured in normal elderly males and females to: (a) determine persistence of the gender-related dimorphism (evident in younger subjects) of CYP3A activity in the elderly population, (b) examine the effect of % ideal body weight, age, diet, and medication use on the activity of human hepatic CYP3A, and (c) compare breath test results obtained in normal geriatric volunteers with published results obtained in younger subjects, to determine aging-related alterations in CYP3A enzyme activity. Erythromycin N-demethylation varied fivefold among these patients. Similar to earlier studies examining erythromycin N-demethylation in younger subjects, CYP3A activity was found to vary with gender in the geriatric cohort. [14C]Erythromycin N-demethylation at 60 min was 3.14% +/- 0.75 (n = 13) in females and 2.15% +/- 0.77 (n = 11) in males (P = 0.005). In evaluating the role of % ideal body weight and % dietary fat using multivariable linear regression analyses, [14C]erythromycin N-demethylation, was found to decline significantly as % ideal body weight increased (P = 0.001). This was not confounded by gender. [14C]Erythromycin N-demethylation was not related to dietary fat intake (P less than 0.13). [14C]Erythromycin N-demethylation in the elderly volunteers was similar to values reported for subjects aged 20-60. Performance of a new non-invasive test of the human hepatic glucocorticoid-inducible CYP3A in a geriatric cohort suggests that: (a) the gender-related heterogeneity in function of the glucocorticoid inducible human CYP3A persists during normal aging, (b) that the activity of CYP3A may decrease in obesity, and (c) that the activity of CYP3A is stable throughout normal ageing.

Pharmacokinetics of terfenadine in healthy elderly subjects

The pharmacokinetics of the terfenadine active metabolite, metabolite I, was examined in ten healthy elderly adults and ten younger adults after single-dose oral administration of 120-mg terfenadine. All subjects successfully completed the study without reporting sedation or other adverse events. Absorption was rapid in both the young and elderly. The mean Cmax was the same for both groups, 501 ng/mL, and occurred at 2.3 hours in the young subjects and 2.5 hours in elderly subjects. However, the apparent clearance was reduced by about 25% in the elderly. After correcting clearance for bodyweight, this difference was not statistically significant.

Discontinuation of a psychogeriatric program for nursing home residents: psychotropic medication changes and behavioral reactions

Changes in medications and behavior were recorded for residents of three nursing homes where a psychogeriatric rehabilitative program was either absent, maintained, or discontinued. Residents without the program received the greatest number of psychotropics. Discontinuation of the program was associated with two problems: (a) fewer reductions in medications and (b) more behavioral difficulties among clients with medication increases. The nursing home with continuous services was the only one where all types of medication changes were followed by an overall decrease in behavior problems or no problems at all.

Clinical pharmacokinetics of anxiolytics and hypnotics in the elderly. Therapeutic considerations (Part II)

Part I of this article, which appeared in the previous issue of the Journal, discussed the scope of and scientific basis for special pharmacokinetic studies of anxiolytic and hypnotic drugs in the elderly, and examined the methodology and results of such studies and the prediction of pharmacokinetic changes. In Part II the authors continue their review, focusing on age-related pharmacodynamic changes in the effects of these drugs, the attempts to correlate pharmacokinetic with pharmacodynamic findings, and the clinical applications of these data.

Steady state pharmacokinetics of hydrolysed bopindolol in young and elderly men

Steady-state pharmacokinetic parameters of the new, long-acting beta-adrenoceptor blocker bopindolol have been measured in 17 young and 20 elderly healthy men. The t 1/2 beta and the AUC(0----24 h) of hydrolysed bopindolol (the active metabolite) were both increased (40% and 26%, respectively) in the elderly subjects but tmax, Cmax and CL/f were not altered. However, after adjusting the parameters to allow for the different average body weights of the two groups, Cmax and CL/f became significantly different (+29% and -30%, respectively). AUC(0----24 h) was increased by 41%. The changes of up to 41% in pharmacokinetic parameters were smaller than the alterations of 50-100% usually seen when titrating doses of antihypertensive drugs. The clinical relevance of the effects was not examined, but similar changes have been reported for other beta-blockers which did not appear to be clinically relevant and did not affect the dosage required to treat hypertension.

Problems and pitfalls in the use of benzodiazepines in the elderly

Benzodiazepines are frequently prescribed for elderly patients living in the community and for those in hospitals and institutions. Their use is more prevalent in women. Prolonged use of benzodiazepines is particularly likely in old age for the treatment not only of insomnia and anxiety, but also of a wide range of nonspecific symptoms. Long term users are likely to have multiple concomitant physical and psychological health problems. The distinction between benzodiazepine anxiolytics and hypnotics is difficult and somewhat arbitrary, since the differences between the compounds are less than their similarities, especially in respect of adverse reactions. Despite their wide therapeutic range, elderly patients are particularly prone to adverse reactions to benzodiazepines. The incidence of unwanted effects, predominantly manifestations of central nervous system depression, has been found to be significantly increased in hospitalised elderly patients, particularly in the frail elderly. Studies on unwanted effects during long term use are scarce, but there is some evidence of tolerance to side effects. However, benzodiazepines have been found to be frequently implicated in drug-associated hospital admissions. There is suggestive evidence that benzodiazepines, especially compounds with long half-lives, may contribute to the falls which are a major health problem in old age. The incidence of benzodiazepine dependence in elderly patients is unknown. The features of benzodiazepine withdrawal in the elderly may differ from those seen in young patients; withdrawal symptoms include confusion and disorientation which often does not precipitate milder reactions such as anxiety, insomnia and perceptual changes. Problems due to both adverse reactions and to benzodiazepine withdrawal may easily be overlooked in multimorbid elderly patients, particularly in those suffering from disorders of the central nervous system. There are numerous studies on benzodiazepine pharmacokinetics indicating that alterations, especially in distribution and elimination of certain compounds, occur in old age. Benzodiazepines with oxidative metabolic pathways and longer half-lives are likely to accumulate with regular administration. However, changes in pharmacodynamics may be more important to explain altered responses to benzodiazepines in the elderly. Although information on pharmacodynamics is still limited, there is convincing evidence of increased pharmacodynamic response in the elderly which may be further accentuated by disease factors. Since the variability of pharmacological response increases with age and is not always predictable, there is good reason at least to start therapy at lower doses and to titrate dosages individually. This may also be appropriate for the newer benzodiazepines, irrespective of advantageous pharmacokinetics.(ABSTRACT TRUNCATED AT 400 WORDS)

Medications of elderly institutionalized incontinent females

The purpose of the study was to explore drug use of elderly incontinent female nursing home residents, to identify potential drug--drug interactions, and to identify the number and categories of drugs taken having the potential to cause urinary incontinence. The medication administration records of 84 female residents were examined. The drugs were categorized by therapeutic classification as designated by the American Hospital Formulary Service. Potential drug--drug interactions were identified using The Hansten Drug Interaction Knowledge Base Program, a microcomputer version of Hansten's (1985) book Drug Interactions. Data were computer-coded and analysed using the Statistical Analysis System (SAS). A total of 454 drugs was taken by the 84 subjects, with an overall average of 5.40 drugs per person. The most frequently taken drugs were gastrointestinal drugs, central nervous system agents, electrolytic, caloric, and water balance drugs, and cardiovascular drugs. Fifty per cent (n = 42) of the subjects were identified as having 119 potential drug-drug interactions. Seventy per cent (n = 59) of the subjects were taking a drug having the potential to cause urinary incontinence. Suggestions for future research are presented.

Clearance of the antihistamine doxylamine. Reduced in elderly men but not in elderly women

A single oral dose of doxylamine succinate 25 mg was administered to 21 young (20 to 43 years) and 22 elderly (60 to 87 years) volunteers. Multiple plasma doxylamine concentrations were determined during a 30-hour period after each dose. Elderly and young women did not differ significantly in peak plasma doxylamine concentration (Cmax) [116 vs 103 micrograms/L], time to Cmax (tmax) [2.4 vs 2.4 h], elimination half-life (12.2 vs 10.1 h), volume of distribution (179 vs 176 L) or clearance (191 vs 218 ml/min). Cmax (107 vs 108 micrograms/L) and tmax (2.1 vs 1.6 h) also did not differ between elderly and young men. However, elderly men had reduced doxylamine clearance (174 vs 240 ml/min, p less than 0.02; 2.5 vs 3.2 ml/min/kg, p less than 0.07) and prolonged half-life (15.5 vs 10.2 h, p less than 0.05). The reduced doxylamine clearance and prolonged half-life in elderly men, but not in elderly women, is similar to results for many other drugs which are transformed by oxidation.

Drug sensitivity in older adults: the role of physiologic and pharmacokinetic factors

Age-related changes in physiology and pharmacokinetics (how drugs are used in the body) lead to increased drug sensitivity and potentially harmful drug effects. This report addresses the heightened sensitivity to drug effects seen in older adults. The first section of the report presents three examples of physiologic decline: a) decreased plasma protein binding affects drug distribution, b) declining liver function affects drug metabolism, and c) impaired kidney function delays drug elimination. The next section illustrates by example the risks associated with altered physiology: a) decline in plasma protein binding may result in an intensified effect of the drug Phenytoin, b) altered liver function increases the sedative effects of Diazepam, and c) declining kidney function results in accumulation of the drug Gentamicin, where toxic effects include kidney failure and deafness. The last section is a discussion of some broad considerations for geriatric pharmacology. Adverse drug reactions can largely be avoided by carefully weighing the needs and clinical status of older persons on an individual basis both prior to and throughout the course of a given drug therapy.

Changes in some hepatic enzyme activities related to phase II drug metabolism in male and female rats as a function of age

Changes in activity of some hepatic enzymes related to UDP-glucuronic acid conjugation (UDP-glucose dehydrogenase and UDP-glucuronyl transferase) and glutathione-related enzymes (glutathione reductase and glutathione peroxidase) were investigated in male and female Wistar rats as a function of age. UDP-glucose dehydrogenase activity showed a decrease in the ageing period in both sexes (26.4% and 37.7% in males and females respectively), and no sex differences were found in all the ages studied. The UDP-glucuronyl transferase (using p-nitrophenol as substrate) showed an age-dependent decrease in its activity for males, but an increase for female rats. A sex difference (male values were higher than female values) was observed only in young rats (1 and 3 months old). Glutathione peroxidase activity increased with age in both sexes (the activity found in male and female old rats was about 162% and 149% respectively to those found in adulthood), and a marked difference was observed between sexes in young and old rats (57.8% and 45.4% higher in females in young and old rats respectively). In contrast, the glutathione reductase activity showed a decrease in the ageing (39% in male and 35.5% in female) and the highest levels during lifetime was found in males.

'Healthy' prescribing for the elderly. How to minimize adverse drug effects and prevent 'dementia in a bottle'

Despite constituting only 11% to 12% of the US population, the elderly use 31% of all prescription and over-the-counter drugs and, unfortunately, are most vulnerable to the adverse effects of drug therapy. Because of age-related physiologic changes and the likelihood of intercurrent disease, elderly patients need individualized prescribing. This requires the practitioner to be familiar with a few drugs in each class that are tolerated by and effective in elderly patients and to adhere to the principles of healthy prescribing, which have application in any setting. In conclusion, the words of Paracelsus (1493-1541) are worth recalling: "All substances are poisons; there is none which is not a poison. The right dose differentiates a poison from a remedy."

Drugs and nutrition in old age

Drug effects are influenced by physiologic and pathologic changes that occur as a consequence of aging. The elderly may be more disposed to drug-induced nutrient depletion because of chronic illness, inadequate diet and long-term drug use. Digoxin, isoniazid, corticosteroids, diuretics and psychoactive agents pose special hazards to the nutritional status of elderly patients. On the other hand, dietary factors, such as protein levels or vitamin deficiencies, may be important determinants of age-related changes in drug disposition or toxicity.

The effects of aging on the hepatic microsomal mixed-function oxidase system of male and female monkeys

Studies were conducted to determine the effects of aging on certain biochemical and biophysical properties of the hepatic microsomes and on the kinetic properties of a constituent drug-metabolizing enzyme and a heme protein in a nonhuman primate. Outbred male and female rhesus monkeys (Macaque mulatta) ranging in age from 1 to 25 years were employed as animal models. There was considerable individual variability, but no significant age or sex-related changes in (1) the concentration of microsomal protein or (2) the content of the cytochromes P-450. Although the oldest animals examined for NADPH cytochrome c (P-450) reductase activity were only 19 years of age, the specific activity of this important enzyme increased rather than decreased during aging. There were only minor changes in the total phospholipid content of the microsomes and none in the distribution profile of the major phospholipid classes. However, the microsomal cholesterol content increased sufficiently to cause a rise in the cholesterol/phospholipid ratio between 16 and 25 years of age. The fluidity of the membrane lipid domain exhibited a concomitant decline as measured by electron spin resonance spectroscopy. There was no apparent correlation between age-related changes in these physicochemical properties of the microsomes and the in vitro activities of the constituent drug-metabolizing enzymes or heme proteins. Furthermore, the marked disparities between the data obtained in inbred male rodents and those from outbred primates suggest that the extrapolation of the former to humans is of questionable value with respect to liver drug metabolism.

Effect of methyltestosterone administration on microsomal drug metabolism in aging rats

The effects of methyltestosterone administration (100 mg/kg for four days) on the hepatic microsomal drug-metabolizing system from old male rats was investigated. Age-related decreases in cytochrome P-450 content, cytochrome c reductase activity and benzphetamine N-demethylase activity were unaffected by methyltestosterone treatment. Administration of the androgen induced nitroanisole O-demethylase and aniline hydroxylase activities, resulting in a restoration of the latter to levels found in young-adult animals.

Drug prescribing for ambulatory patients 85 years of age and older

Drug prescribing for ambulatory patients greater than or equal to 85 years of age was studied using data from the 1980 National Ambulatory Medical Care Survey (NAMCS) on office visits to physicians. NAMCS is a survey by the US National Center for Health Statistics, which collected information on office visits and extrapolated the results to the US population. Of the 575.7 million office visits by all ages, 6.8 million (1 per cent) were by persons greater than or equal to 85 years of age, and 64 per cent involved females. Ninety per cent of the total office visits of those greater than or equal to 85 years were with a physician who had seen them before; 94 per cent were with MDs as compared with DOs; 56 per cent were with general practitioners or internists; and 95 per cent had some type of follow-up planned. The most frequent duration of the office visit was 11-15 minutes (36 per cent). The most frequent diagnostic class was diseases of the circulatory system. The survey physicians were asked to list all drugs, new or already in use by the patient, that were ordered, administered, or prescribed during the visit. The authors converted the drug brand names to their nonproprietary or generic name component(s); each active ingredient of combination products was treated as a separate drug entity. All drug analyses used generic names. Thirty-two per cent of visits did not involve the use of any drug, 21 per cent involved one drug; 12 per cent, two drugs; and 16 per cent, three drugs. Cardiovascular-renal drugs were the most frequently mentioned. One-third of the visits involved the use of one or more drugs that have psychologic effects, either intended or as side effects. Three per cent of the office visits involved the use of two or more drugs that had the potential for clinically important interactions.

Antipyretic analgesic drugs as models for studies of drug disposition in old age

Alterations in drug metabolizing capacity associated with the aging process can be elucidated using analgesic-antipyretic agents as model compounds. Antipyrine serves to profile drug oxidizing capacity. Drug oxidation is significantly impaired in old age, but age-related changes are far greater in men than in women. Acetaminophen analogously serves to profile conjugating capacity, which is minimally influenced by age both in men and in women. Changes in the capacity to biotransform these model compounds are reasonably well predictive of parallel changes in the same person's ability to metabolize other drugs transformed by the same pathway.

Reduced clearance of triazolam in old age: relation to antipyrine oxidizing capacity

Thirty-three healthy male and female volunteers aged 21 to 87 years received a single 0.5 mg oral dose of triazolam. Plasma triazolam concentrations were measured in multiple samples drawn during 24 h after the dose. Mean triazolam elimination half-life was not significantly different between young and elderly men (3.0 vs 4.6 h), nor between young and elderly women (2.7 vs 3.2 h). However, apparent oral clearance of triazolam was significantly reduced in elderly as compared to young groups of both sexes, leading to higher peak plasma concentrations and increased total area under the curve. Values of half-life and clearance of antipyrine, a low-extraction hepatically oxidized compound, were poorly correlated with those of triazolam (r = 0.34 and 0.44, respectively), suggesting different mechanisms controlling age-related changes in clearance of these two hepatically oxidized drugs.

Depression in the elderly: pharmacologic considerations in treatment

The pharmacologic treatment of depression in the aged is complicated by an increased frequency of concurrent medical disease and multiple drug use. In addition, age-related physiologic changes may alter the pharmacokinetics and pharmacodynamics of the antidepressant medications. As a consequence, the variability of response and the incidence of adverse effects are increased in the elderly. The clinical implications of these factors and guidelines for the use of antidepressants in the elderly are discussed.