In my clinical experiences in the past five years included many geriatric patients.  One patient, in particular, comes to mind when I reflect on the patient’s history and the pharmacokinetic and pharmacodynamic processes and how age and lifestyle choices were a factor.  Often, older patients take more medications than younger generations because of the likelihood of having numerous medical disorders.  Geriatric patients may have drugs that are a short or long-term prescription, but each one affects the patient.

Pharmacodynamics

M.M. was a 70 y.o. patient in our clinical setting that had a medical diagnosis of hypertension.  This patient was on metoprolol, a frequently used beta blocker.  M.M. was also a smoker with a half a pack a day 40-year history.  This patient reported attempts of smoking cessation a few times throughout the years but was not successful.  Throughout caring for this patient, he voiced understanding the importance of smoking cessation and was receptive to patient education concerning smoking cessation.

According to NSW Government (n.d.), medication levels can vary if a person smokes and interactions are caused by constituents of tobacco smoke inducing cytochrome P450 enzymes in the liver affecting absorption, distribution, metabolism, or elimination of the medication.  Beta blockers have a moderate effect on patients who use tobacco, therefore, may require a higher dose of the medication NSW Government (n.d.).  If the patient decides to quit smoking, they may experience possible bradycardia and hypotension, resulting in requiring a lower dose NSW Government (n.d.).  Beta blockers decrease blood pressure by blocking central and peripheral beta receptors, resulting in reduced cardiac output and sympathetic outflow (Arcangelo, Peterson Wilbur, & Reinhold, 2017).

Pharmacokinetics in Elderly Patients

Each of the body systems is affected by age.  The impact of aging on the pharmacokinetics of medications includes:

•    Absorptive changes such as decreased blood flow, increased gastric pH and delayed gastric emptying (Arcangelo et al., 2017).

•    Distribution changes including decreased albumin, decreased lean body mass and increased body fat (Arcangelo et al., 2017).

•    Metabolic changes such as decreased blood flow to the liver and reduced enzymatic activity (Arcangelo et al., 2017).

•    Excretion changes; examples include decreased glomerular filtration and decreased secretion (Arcangelo et al., 2017).

The pharmacokinetics of beta blockers can be affected by age, race, cigarette smoking and other drug therapies (Frishman & Alwarshetty, 2002).  Beta-1 receptors are located primarily in the heart and kidney.  These receptors are responsible for heart rate, renin release, and cardiac contractility (Arcangelo et al., 2017).  Beta blockers decrease blood pressure by blocking central and peripheral beta receptors, resulting in reduced cardiac output and sympathetic outflow (Arcangelo et al., 2017).

Plan of Care

As mentioned previously, M.M. was receptive to patient education on smoking cessation.  He did have support from his family to assist with this plan.  M.M. was able to participate in the plan of care as he voiced what did not work for him previously in his attempts to quit smoking.  He was open to ideas from the healthcare team and understood the benefits of smoking cessation on his health, lifestyle, and effect on his loved ones.

References

Arcangelo, V. P., Peterson, A. M., Wilbur, V. & Reinhold, J. A.  (Eds.). (2017). Pharmacotherapeutics for advanced practice: A practical approach (4th ed.). Ambler, PA: Lippincott Williams & Wilkins.

Frishman, W.H., & Alwarshetty, M. (2002).  Beta-adrenergic blockers in systemic hypertension: pharmacokinetic considerations related to current guidelines.  Clinical Pharmacokinetics, 41(7), 505-516.

NSW Government (n.d).  Medication interactions with smoking and smoking cessation.  Retrieved from http://www.health.nsw.gov.au/tobacco/Publications/tool-14-medication-intera.pdf.