Medication Utilization - Potential Medication Problems of the Elderly

Understanding Potential Medication  Problems of the Elderly

A useful model for understanding potential medication  problems for elderly patients is reviewed in a series of  guidelines contained in the Drug-related Problems Model. Strand LM, Morley PC, Cipolle RJ. Drug-related problems:  their structure and function. Drug Intell Clin Pharm  1990;24:1093–7.

• The patient has a medical condition for which a medication  is indicated but the patient has not been prescribed a  medication
• The wrong medication has been prescribed for a specific  condition
• The dose of the drug is too low for a therapeutic effect
• The dose of the drug is too high causing possible toxicity or  other adverse effects
• Patient becomes symptomatic because of a side effect or  adverse reaction to a drug
• Food-drug, drug-drug, or disease- drug interactions are (is)  present which in turn cause another medical problem

DOSE RELATED COMPLICATIONS

Dose related problems could be specific for elderly  patients. Pharmacokinetics is a specialized branch of  pharmacy practice that tailors the dose of a medication to  specific populations and physiological parameters unique  to the individual.

The following is a list of considerations for the elderly that  are important for dose adjustment and tailoring. This list is  not comprehensive as clinical pharmacokinetics is a highly specialized area of pharmacy and beyond the scope of  this tool. The take home messages are: for any individual  elderly patient dosing is not always similar to a nonelderly  individual; and dose related problems should be referred for  pharmacokinetic consultation.

DOSE RELATED PROBLEMS AND THE ELDERLY

Specific physiological changes in the elderly place older  adults at increased risk for DRP’s.

• The absorption, distribution, metabolism and elimination of  drugs (ADME) in the body of elderly persons can be altered by  specific physiological changes in aging.
• The ADME of any particular drug in the body is dependent  upon the physiochemical properties of the drug; patient  related variables such as individual body composition  and weight; the presence of disease, altered physiological  functioning, and the presence of other drugs in the body.
• All drugs have a “therapeutic window.” If you can think of  the window as composed of the glass enclosed in a top sash  and bottom sash, proper therapeutic concentration is within  the window. Any concentration of a drug in the body over the  top sash can be toxic or lead to other complications while  concentrations under the bottom sash can be sub therapuetic.
• Drug concentration may either be increased (possible toxicity)  or decreased (possible sub therapeutic response) as a result  of physiological changes in the elderly.  

DRUG DISPOSITION IN THE ELDERLY

The most common changes that can affect ADME in the  elderly are as follows:

Changes in lean to fat tissue

• Affects fat-soluble drugs

Changes in fluid and water retention

• Affects water soluble drugs

Changes in glomerular filtration rate

• Slows down rate at which drugs are eliminated by the kidney  Decrease in liver function often due to disease
• Affects clearance of hepatically metabolized drugs because of  changes in the activity of drug metabolizing enzymes

Cerebral vascular and coronary artery disease

• Reduced blood flow to the brain and reduced cardiac output  can modify the distribution of drugs to target tissues and  organ systems

Changes in intestinal motility and function

• Affects drugs whose primary absorption site is in the intestine Decline in plasma albumin
• Affects the concentration of protein binding drugs

Dose adjustments or medication changes may be needed to  account for these factors in any individual patient

MEDICATION USE ASSESSMENT: UTILIZING THE  MEDICATION APPROPRIATENESS INDEX

Hanlon JT, Schmader KE, Samsa GP, Weinberger M, Uttech  KM, Lewis IK, et al. A method for assessing drug therapy  appropriateness. J Clin Epidemiol 1992;45:1045-51.

The questions contained within the Medication  Appropriateness Index are a useful tool for assessing  medication utilization problems. These questions can  be explored with either the prescriber or a pharmacist  dispensing the medication.  

• Is there an indication for the drug?  
• Is the medication effective for the condition?
• Is the dosage correct?  
• Are the directions correct?  
• Are the directions practical?  
• Are there clinically significant drug-drug interactions?
• Are there clinically significant drug-disease interactions?
• Is there unnecessary duplication with other drugs?
• Is the duration of therapy acceptable?
• Is this drug the least expensive alternative compared to  others of equal utility?  

ADHERENCE

McLaughlin et al. Drugs Aging 2005; 22 (3)

• Adherence can be defined as the extent to which  medication administration coincides with medical advice  and instructions
• 30 to 50 % of the ambulatory population does not adhere  with their medication directives and non-adherence can be  as high as 60% in the elderly
• Adherence varies with the disease state; number and type  of medications taken; characteristics of the patient; the  nature of communication between practitioner and patient;  and economic factors
• Elderly patients not adhering with medications results  in 10% of hospital admissions and 23% of nursing  home admissions

NON-ADHERENCE BEHAVIORS IN THE ELDERLY • Not filling the prescription

• Not refilling the prescription
• Prematurely quitting the medication
• Taking more or less of the medication prescribed
• Not taking the medication according to the dosing schedule  
• Not taking the medication according to special instructions  such as taking on an empty or full stomach (can effect  absorption or cause stomach problems)
• Taking medication not prescribed (sharing medication) 6

RISK FACTORS FOR NON-ADHERENCE

Asymptomatic diseases

• Hypertension, osteoporosis, hypercholesterolemia
• Diseases that do not have symptoms in the early stages  of their natural history have high rates of non-adherence  because patients assume if they do not have pain or other  symptoms they must not be ill
• Patient education is critical, explaining in lay language  the consequences if the disease is not treated in the early  stages. Example: stroke and heart attack for uncontrolled  hypertension
• Explaining the pathophysiological change in the body when  medication is not taken helps the patient understand the  role medication plays in prevention.

Multiple medications with complex dosing or  administration schedules

• The elderly may have memory problems, diminished  eyesight, hearing, arthritic hands that make opening bottles  or administering medications difficult
• Counsel family members or caregivers to monitor  medication taking if possible
• Pill organizers that can be filled weekly
• Special bottle caps and large print
• Simplifying the regimen by eliminating duplication
• Prescribing extended release medications or medications  in alternative formulations that require less frequent  administration  

Side effects of medication

• Unanticipated side effects are more likely to cause premature  discontinuance of medication
• When patients can anticipate side effects and have some  means for managing the side effects, they are less likely to  discontinue taking the medication (we all like to feel in control  of our health)
• The most frequent side effects and side effects with lethal  consequences should be discussed in patient counseling
• Ways of managing the side effects, when to quit taking the  medication if serious side effects appear and which ones to  report to the doctor should all be discussed.

Social and economic barriers

• Transportation barriers
• Lack of convenient access to a pharmacy

Health literacy

• Lack of educationally appropriate and culturally sensitive oral  and written drug information material
• Language problems with recent immigrants
• Training for all health professionals in how to deliver culturally  sensitive, and educationally appropriate oral and written  medication information tailored specifically to the patient’s  needs is essential
• Assessment of the patient’s economic and living situation and  referral to appropriate agencies for assistance should be an  integral part of care for the elderly

QUESTIONS FOR A WELL-INFORMED ELDERLY  CONSUMER OF MEDICATION

• Elderly patients should be able to answer all of these  questions for their medications.
• Why is the medication prescribed?
• How is the medication controlling my symptoms and  preventing further disease?
• How should I take this medication? How much? When?  Special dosing considerations?
• What side effects should I be aware of? How can I manage  my side effects? What side effects should I report to my  physician? Should I immediately stop taking a medication  when I experience a side effect?
• What other medications could this medication interact  with and does the prescriber know my complete medical  and medication history? Are there any interactions with food or alcohol that  I should be aware of?