Pharmacokinetics: Due to a variety of reasons [prostatism (conditions governing chronic disease of prostate gland), nephrosclerosis (a condition involving hardening of kidneys), UTI (Urinary Tract Infection)] renal clearance is reduced. Thus drugs are excreted slowly and elderly patients are at greater risk from nephrotoxic agents. Great care needs to be taken while administering drugs with narrow safety margin between therapeutic and toxic dose such as digoxin. As a thumb rule one should take tissue concentration of drugs to be 50% more in elderly than younger patients.
Adverse Reactions: Many side-effects present themselves in a non-specific manner. Mental confusion, constipation, postural hypotension and falls are common.
Use of hypnotics with long half life should be avoided. Diuretics are over-prescribed in the elderly. They should not be used on long-term basis. Blood disorders caused by drug therapy are much more common in the aged. Therefore drugs which depress bone marrow function, such as co-trimoxazole, mianserin, should not be used unless an acceptable alternative is not possible. Bleeding associated with NSAIDs and aspirin are more common in the elderly.
General Guidelines: One should prescribe drugs to the elderly only when clearly indicated. It is better to prescribe established drugs from a limited range, which have been well tried out and whose effects in the elderly are well known.
Dosage should generally be 50% of the adult dose. Repeat prescriptions should be written only after thorough review. It is often possible to withdraw a drug altogether. Sometimes dosage may need to be tailored to match diminishing renal function.
If possible, no more than three drugs should be prescribed at a time to be taken no more than twice daily. In particular, drug regimens which call for complicated, confusing and different dosage intervals should be avoided.
A close live-in young relative of the elderly should be explained the dosage regimen so that even by mistake the patient does not consume more than medically advised.
Source: MIMS INDIA, October 1998. Reproduced with permission.
This column in the drug profile lists down all other precautions and warnings that a person consuming the drug must know. Any specific condition for which the drug must not be used or used with caution, for example, diabetes, heart attack patients, etc., are also listed in this column.
A drug may cause other several different effects in your body, besides producing the desirable beneficial effect for which it is consumed. These other effects are of two types (although we have listed all of them under the same heading for the sake of convenience): Possible Side Effects and Possible Adverse Effects.
These effects are natural, expected and usually unavoidable actions of the drug. Whenever a drug is consumed (by any route) it is distributed all throughout the body and not restricted to just one particular organ in the body. Thus a drug produces the desirable effect in one particular organ for which it is taken and undesirable effects in all other organs where it also acts simultaneously. For example, anticholinergic drugs are taken to relieve spasm in the wall of the intestine, but they also affect the eyes causing blurred vision, the mouth causing dryness and the urinary bladder causing retention of urine. All the effects caused in organs other than the intestine are undesirable and will be called `Side-Effects' of Anticholinergic drugs. Such side-effects disappear slowly as the body gets used to the drug. One must consult the doctor if the side-effects are troublesome or persist for a long period of time. The doctor may change the drug or the dosage regimen so as to reduce the side-effects. Sometimes a patient may have to tolerate the side effects of certain drugs which are the only available drug for the treatment of their disease - which itself may be very serious and could prove fatal (that is, cause death of the patient) if left untreated, for example, a disease like cancer. In such cases regular and careful observation (monitoring) by the doctor throughout the treatment is necessary. Hence a doctor always evaluates the benefits (therapeutic effects) and risks (possible adverse effects) of a drug treatment before prescribing a drug.
Possible Adverse Effects
Adverse effects are unexpected, unusual and unpredictable reactions of the drug. They may be caused because the patient is allergic to the drug or due to some genetic deficiency in the patient such as the lack of an enzyme which inactivates the drug may lead to accumulation of the drug causing adverse reactions. They may also occur due to interactions with other drugs.
Adverse effects may be either mild or serious in nature, which determines the steps one should take if they occur. This column of the drug profile tells you what adverse effects or side-effects to expect once you take a particular drug, how frequently may an adverse/side effect occur and what to do in case it occurs.
One should always be alert to significant changes that occur in one's body while taking drugs especially those drugs which are known to produce adverse effects. One may also experience certain reactions which are not yet reported and hence not listed in this column. In such cases, the doctor should be consulted immediately.