In a study conducted in the United States, known results are quite astonishing that 25% of drugs used in the elderly including psychotropic class.
In the use of drugs, the elderly often face the problem caused by the tendency of taking the drug simultaneously due to the many types of illness.
Physiological condition of those who are elderly have a lot of setbacks, resulting in the pharmacokinetics and pharmacodynamics (drug effect) that is changing. That is, the elderly have a two times higher risk of getting side effects from drug interactions.
Physiological changes and Farmakokinesis
Pharmacokinetics is the journey and the fate of drugs in the body, including the start of the drug into the body until it was reissued. With age, a change in physiological function that also affect a change in the pharmacokinetics of either drug distribution, absorption and elimination of the drug as well. Let’s look at each.
Absorption is the process of absorption of the drug from drug delivery to the systemic circulation. In general, except for the absorption of drugs require intravenous administration.
Changes in drug absorption in the elderly is not known, but it apparently has not changed for most drugs. Circumstances that may affect absorption include changes in eating habits, high consumption of non-prescription drugs (such as antacids, laksansia) and slower gastric emptying rate.
After absorbed, the drug will be distributed throughout the body via the blood circulation. The elderly drug distribution changes. Besides the physico-chemical properties of drug molecules, the distribution is also influenced by body composition, plasma protein binding, and organ blood flow.
With increasing age, the percentage of total water and body mass that contains fat (lean body mass) become fewer. Drugs that have a lipophilic nature (soluble in fat but not water soluble) are small, such as digoxin and propranolol, to higher levels in the blood, although the usual dose for adults.
It usually occurs in older adults also changes in albumin globulin ratio. Albumin decrease markedly in the elderly is generally due to reduced physical activity and may also provide clues suffered systemic disease severity, such as acute myocardial infarction, inflammatory diseases, and severe infections that drugs are primarily bound to albumin would be more in the free form.
In other words, the levels of these drugs will increase in the plasma. Drug molecule bound to albumin is a weak acid.
The psychotropic drug biotransformation takes place mainly in the liver. In old age, weight and blood flow in the liver had decreased by 40-45% the effect on drugs biotransformasinya speed depends on liver blood flow such as imipramine, amitriptyline, desipramine and also nortiptilin.
Liver plays an important role in drug metabolism. Not only activate drugs or terminate drug action but also helps the formation of a more polar metabolites ionized allowing ongoing renal excretion mechanism.
Capacity of the liver in the metabolism of drugs not shown to change with age, but clearly there is a decrease in liver blood flow is thought to greatly affect the ability of drug metabolism.
In addition, renal excretion which is where most of the drug, either in the form of inactive metabolites and results, as well as physiological and anatomical changes with age.
With decreasing renal function capacity due to old age, the elimination of most drugs will also be affected. The drugs are metabolized to the active form, such as: methyldopa, triamterene, spironolactone, oksifenbutazon, levodopa, and acetoheksamid may accumulate because of worsening renal function in the elderly.
Instructions for Use Drugs
Various studies show that there is a strong correlation between the number of drugs taken by the occurrence of drug side effects. The more types of prescription drugs in the elderly, the higher the likelihood of side effects.
Epidemiologically, 1 out of 10 people (10%) will experience side effects after administration of one type of drug. This risk is known to be increased to 100% if the amount of drugs given to 10 species or more.
Therefore, the use of drugs in the elderly should be considered carefully. The drugs often cause side effects in the elderly include analgesics, anti-hypertensive, anti-parkinsion, anti-psychotics, sedatives, and gastrointestinal drugs.
It is important to know the information about previous drug use needs to be asked, given before the patient comes to the doctor usually have their own treatment efforts. This information is needed to determine whether the complaint / illness is related to drug use (side effects).
Drug should be given appropriate diagnosis and its use is strictly controlled. Individual dose adjustment is needed in order to avoid the possibility of adverse effects.
As much as possible do not give more than 2 types of drugs. If forced to give more than one kind of drug, consider how the provision can be done at the same time.
Changes in the pharmacokinetics of drugs that experienced the elderly need to be considered, especially in terms of the use of psychotropic drugs in light of a very close association with the risk of side effects or drug interactions.