Polypharmacy happens when one patient purchases medicine from more than one pharmacy. Complementary medicines are becoming increasingly popular, and that has become so common among patients who use both medicines as a ‘treatment’ for their diseases. The potential drugs to drugs interaction cannot be underestimated. It can affects both the pharmacokinetics and pharmacodynamics.
metoprolol( for hypertension), digoxin, celecoxib(osteoarthritis),diazepam(sleep)
1)Affects Pharmacokinetics:
Take my grandmother as an example, she age 72, considered old age, we have to realise that ageing does affects how drugs act.We got to get clear of the three components of pharmacokinetics: Absorption, distribution and clearance.
1.Absorption
Though Absorption after oral administration is least affected , the Gastrointestinal (GI) system is affected by ageing which contribute to the of stomach protection and an increased risk of gastritis and ulcer formation. The use of non-steroidal anti-inflammatory drugs (NSAIDs- Celecoxib and Ibuprofen), aspirin, warfarin threaten GI bleed.
2.Distribution
For the elderly, medication gets distributed into either fats or water, depending on its chemical characteristics .
The % body fat in elderly increased, making the diazepam (fat soluble) stay longer in the body
The %body water in elderly decreased, blood levels of drugs that are water soluble are higher.
The serum protein (albumin) production decreases. Less drug is bound to albumin , increased serum levels of displaced drugs.
1. Clearance
Blood flow to liver decreases and clearance of certain drugs may be reduced by 30-40%.
Size of kidney and renal blood flow decrease, cause renal clearance reduced up to 50%.
2) Affects Pharmacodynamics:
Increased sensitivity to medication
Benzodiazepines, antidepressant, antihistamine containing cough remedy, with the low blood pressure caused by GI bleed.
Thus we need to protect the elderly patients from potentially harmful effects of polypharmacy by:
· Knowing which drugs frequently cause problems to the elderly.
· All medication that the patients take(prescription, OTC, complementary medicines) should be documented.
· Patients’ lab value (liver and renal function test) should be monitored closely.(Ageing affects how drugs are cleared from the body)
· Clear therapeutics endpoint should be established at the beginning of the treatment.
· The prescriber must rely on his clinical judgement and knowledge of the patient’s condition.
· Medicines should begin in low doses and increase slowly in small increment.
· Pharmacist perform medical reviews and counsel patients on the potential side effects of medication to minimise polypharmacy problems.
Polypharmacy has become a common problem among Malaysians. However,I believe these problems are less likely to occur if one physician oversees the patient’s medication regimen, not only that, the steps listed above should also be taken by patients and families to help curbing the harmful side effects of consuming too much medications.
References:
1. ~ Wiliam CM(2002) Using medication approprotely in older adults. Am Fam Physician,66 1917.
2. ~Lim WK, Woodward MC(1999) Improving medication outcomes in older people. Aust J Hosp Pharm 29:103.
