Medications for the elderly

Multiplicity of pathology, high risk of destabilization in patients of older age groups leads to the fact that medicines for the elderly have become increasingly used in geriatrics. Peculiarities of pharmacokinetics, pharmacodynamics, therapeutic and toxic effects of drugs in the senile organism, and also the possibility of using geroprotectors are studied by geriatric pharmacology.

Age features of pharmacokinetics consist in the fact that in elderly and elderly people absorption of substances from the gastrointestinal tract slows down, the distribution and transport of drugs in the body changes, the rate of biotransformation in the liver decreases, and the excretion of medicines slows down.

Most often in geriatric practice, oral medications are used for the elderly. The first stage of pharmacokinetics is absorption of them in the gastrointestinal tract. With age, the suction surface of the digestive organs decreases, the secretory function of the digestive glands decreases and the enzymatic activity of the digestive juices decreases, the blood flow in the mesenteric vessels decreases - all this leads to a slowing of the dissolution rate of the drug and its absorption. Of particular importance is the motor function of the intestine and its change under the influence of medications: constipation and medication for the elderly, contributing to the slowing of intestinal peristalsis (atropine, platifillin, tricyclic antidepressants, antiparkinsonics, phenothiazine neuroleptics, etc.), lead to increased absorption of drugs; rapid fluid stool and the use of laxatives and metoclopramide reduce the absorption of concomitantly used drugs.

With subcutaneous and intramuscular administration of drugs, the effect occurs later due to a decrease in cardiac output, slowing of blood flow velocity and compaction of the walls of blood vessels.

The second stage of pharmacokinetics is the distribution, depending on the protein composition of the blood, the water-electrolyte state, the level of functioning of the cardiovascular system. In addition, the distribution largely depends on the properties of the medication used for the elderly. Thus, water-soluble drugs for the elderly are distributed in extracellular spaces, while lipid-soluble drugs are distributed in the intracellular and extracellular spaces.

In elderly patients there is a decrease in albumen content, a decrease in muscle mass and water, an increase in the body fat content, as a result of which the distribution and concentration of drugs in the blood changes.

Reduction of blood flow velocity, intensity of peripheral circulation also increases the duration of circulation of medicinal substances and increases the risk of intoxication.

As you know, medications for the elderly in the blood are bound by plasma proteins (more often albumins); associated with the protein, they are not active. If there are 2 or more drugs in the blood, then the one that has a greater ability to bind to the protein displaces the less active. This, along with the age-related decrease in the level of albumins, leads to an increase in the content of the free fraction of the drug for the elderly, which creates the danger of toxic effects. Especially it is expressed in relation to sulfonamides, benzodiazepines, salicylates, cardiac glycosides, purine antispasmodics, indirect anticoagulants, phenothiazide antipsychotics, oral antidiabetics, narcotic analgesics and anticonvulsants.

Shifts in the protein composition of the blood, observed with aging, may be the cause of the altered transport of medications administered, the slowed-down rate of their diffusion through the vascular-tissue membranes.

Reducing muscle mass and water in the elderly and elderly leads to a decrease in the distribution of drugs, accompanied by an increase in the concentration of water-soluble drugs in blood plasma and tissues and an increased risk of overdose of such drugs as medications for the elderly, namely: aminoglycolide antibiotics, dipzhein, hydrophilic beta - adrenoblockers (atenolol, tenormin, nadolol, sotalol), theophylline, blockers of histamine H2-receptors.

In connection with the relative increase in lipid content in old age, the volume of distribution of fat-soluble drugs increases with a decrease in their concentration in the blood plasma, which leads to a delay in the onset of the effect, an increase in the tendency to accumulation, prolongation of the pharmacological activity of such drugs as tetracycline antibiotics, benzodiazepines, ethanol, phenothiazine antipsychotics , sleeping pills.

With age, there is a change in the biotransformation (metabolism) of drugs, due primarily to a weakening of the activity of liver enzyme systems, a decrease in the number of hepatocytes and a decrease in hepatic blood flow (0.3-1.5% per year). At the same time, biotransformation of preparations slows down, their concentration in blood and tissues increases, side effects usually develop, the risk of overdose increases.

It is important to note that the activity of the enzymes providing the glucuronization process for medicines does not change with age with age, therefore it is preferable to prescribe medications that are inactivated in this way in the elderly, all other things being equal.

It should also take into account the fact that in some people of elderly and senile age the rate of biotransformation of medicinal substances is not subject to age-related changes.

The next stage of pharmacokinetics is the removal of drugs from the body. In geriatric patients, the blood flow in the kidneys decreases, glomerular filtration decreases, the number of functioning nephrons decreases, tubular secretion decreases with a decrease in creatinine clearance as a result (in persons over 65 years of age it is 30-40% of those of middle-aged people). Drug allocation slows down. This is facilitated by the lengthening of the entero-hepatic circulation of drugs and their metabolites (due to hypokinetic dyskinesia of the biliary tract and increased backward absorption with reduced intestinal peristalsis).

[1]

The basic principles of drug therapy in geriatrics

It should be limited as little as possible (1-2 medications for the elderly) with the number of drugs that should be taken as simple as possible (1-2 times per day). Only those medications should be prescribed, the medicinal and side effects of which are well known.

If it is possible to achieve therapeutic effect by non-drug methods, then, if possible, they should be used.

To treat is necessary the basic disease or the syndrome determining at present the severity of the patient's condition.

It requires a special individualization of treatment, the selection of optimal dosages for a given patient of medicines.

Use the rule of small doses (half, one third of the usual dose), then slowly increase it until the therapeutic effect is achieved and adjust the maintenance dose.

It is expedient to prescribe complex medicinal preparations with a multidirectional effect on the patient's existing diseases.

Use medicines for the elderly and diet, normalizing the reactivity, metabolism and functions of the aging organism, reducing the risk of adverse reactions: complexes of water- and fat-soluble vitamins, vital micro- and macroelements, amino acids, adaptogens.

It should be remembered that the effect of drugs administered enterally may occur later and be inadequate due to the age-related deterioration of their absorption in the gastrointestinal tract.

It is necessary to control the consumption of liquids and the release of urine, the state of kidney function. Inadequate fluid intake may contribute to the development of drug intoxication.

Long-term use of many drugs (soothing, analgesic, hypnotics) leads to tachyphylaxis (addiction) and increasing their dosages, increases the risk of intoxication. Need frequent replacement of drugs, the use of "pulse therapy."

In the conditions of a polyclinic, prescribed recommendations and medications for the elderly should be written down for the patient and given to him in the hands.

Among persons receiving polypharmacotherapy, patients should be identified with the risk factors for toxic, side effects and paradoxical effects of drugs. This group of patients should include patients with a complicated allergic history, signs of renal or hepatic insufficiency, with reduced cardiac output, progressive weight loss, hypoalbuminemia. An increased risk of complications of pharmacotherapy is observed in patients older than 80 years with a changed neuropsychological status, reduced hearing and vision.

At each visit to the patient, check what medicines for the elderly and how many of the prescribed funds the patient takes. To recommend the patient to keep a diary of the sensations connected with treatment.

Regularly monitor the parameters of physiologically important processes (arterial pressure, pulse, diuresis, electrolyte blood composition), not allowing dramatic changes in their magnitude.

Age-related changes in physiological processes

Reduction of the suction surface of the gastrointestinal tract, a decrease in mesenteric blood flow, an increase in the pH of gastric contents, a slowing of peristalsis.

[2], [3], [4], [5], [6]

Disturbance of absorption

Decrease in muscle mass, the total amount of fluid in the body, albumin content, increase in the content of acidic α-glycoprotein, the amount of fat, the change in the bonds of drugs with proteins.

[7], [8], [9], [10], [11]

Distribution Failure

Decrease in hepatic blood flow, mass of liver parenchyma, decreased activity of enzymes.

[12], [13], [14], [15], [16], [17], [18]

Metabolic disorders

Reduction in the number of functioning nephrons, reduced glomerular filtration rate and secretory function of the renal tubules, delayed excretion of excreta through the gastrointestinal tract, skin, lungs.

Disruption of excretion

For example, sensitivity to neuroleptics causing confusion, increased extrapyramidal symptoms, orthostatic hypotension and delayed urination increases. The use of nitrates and novocainamide is accompanied by a greater decrease in arterial pressure than in middle-aged people and a possible worsening of cerebral circulation. An increase in sensitivity to anticoagulants has been observed.

On the other hand, in elderly people, adrenaline, ephedrine and other adrenomimetics are less effective. Atropine and platifillin less affect the heart rate and have a less spasmolytic effect (a change in the binding of the drug to M-holinoretseptorami).

The anticonvulsant effect of barbiturates is less pronounced. The hypotensive effect of beta-blockers is reduced, and the number of side effects increases with their application.

[19], [20], [21], [22], [23], [24], [25]

Summary of changes in pharmacokinetics in aging

Medicines for the elderly are determined not only by their concentration in the body, but also by the functional state of the tissue or the target organ and receptors. With aging, the number of receptors of the nervous tissue decreases, functional depletion and a decrease in reactivity occur, which often leads to the development of inadequate amounts of the administered agent and even paradoxical reactions with the use of cardiac glycosides, glucocorticosteroids, nitrates, adrenomimetics and adrenoblockers, certain antihypertensives, analgesics, barbiturates, benzodiazepines tranquilizers, antiparkinsonian and anticonvulsants. The appearance of perverse reactions to medications is facilitated by reduced physical activity, a tendency to constipation, vitamin deficiency, deterioration of the blood supply of tissues and a relative predominance of excitatory processes in the nervous system in the elderly and senile age.