Medication Optimization in Older Adults, Pregnancy, and Renal/Hepatic Disease

Optimizing medications in special populations recognizes that the same drug can behave very differently depending on a patient's age, organ function, or physiological state. Older adults, pregnant patients, and people with kidney or liver impairment have altered pharmacokinetics and pharmacodynamics, and may be more vulnerable to harm, so therapy must be tailored to these characteristics.

Definition

Medication optimization in special populations is the tailoring of drug selection and use to physiological states and organ-function characteristics — such as ageing, pregnancy, and renal or hepatic impairment — that alter how the body handles or responds to medicines and that change the balance of benefit and risk.

Scope

The topic explains, at a conceptual level, why and how medication optimization differs in older adults, in pregnancy, and in renal or hepatic disease, including the physiological changes that alter drug handling and the tools used to characterize organ function. It is a reference overview of the principles and is not a source of dosing, drug-selection, or treatment advice for any individual.

Key concepts

• Altered pharmacokinetics and pharmacodynamics
• Estimated glomerular filtration rate (eGFR) and renal clearance
• Hepatic metabolism and impairment
• Physiological changes of pregnancy
• Teratogenicity and fetal exposure
• Potentially inappropriate medications in older adults
• Frailty and geriatric syndromes

Key theories

Geriatric syndromes and vulnerability

Inouye and colleagues describe geriatric syndromes as multifactorial conditions arising when accumulated impairments across several systems make older adults vulnerable to situational challenges, including medications; this concept explains why drugs that are well tolerated in younger adults can precipitate falls, delirium, or other harms in frail older patients.

Mechanisms

Each special population alters drug handling in characteristic ways. In older adults, reduced renal clearance, changes in body composition, polypharmacy, and increased target-organ sensitivity raise the risk of accumulation and adverse effects. In renal impairment, drugs and active metabolites cleared by the kidney accumulate as glomerular filtration falls, so estimating kidney function — for example with eGFR equations such as CKD-EPI — is central to assessing risk. In hepatic disease, impaired metabolism, altered protein binding, and portosystemic shunting change exposure to hepatically cleared drugs. In pregnancy, expanded plasma volume, increased renal clearance, altered enzyme activity, and the placental barrier change maternal drug exposure and introduce the distinct consideration of fetal exposure and teratogenic risk.

Clinical relevance

Recognizing altered drug handling in these populations is fundamental to safe medication review, because a regimen that is appropriate for a typical adult may carry excess risk for a frail older person, a pregnant patient, or someone with organ impairment. This entry conveys the underlying principles for reference and education only; it does not provide dosing, drug-selection, or individualized treatment recommendations, which require clinical assessment.

Epidemiology

These populations are large and growing: the number of older adults on multiple medicines is rising, chronic kidney and liver disease are common, and a substantial fraction of pregnant people take at least one medication, so questions of medication optimization in special populations arise routinely in practice.

Evidence & guidelines

Guidance draws on pharmacokinetic principles, on organ-function estimation tools (such as validated eGFR equations), and on explicit appropriateness criteria for older adults (Beers Criteria; STOPP/START). Pregnancy-related evidence is constrained because pregnant people are typically excluded from trials, so it relies heavily on observational data and pharmacokinetic modelling, and regulatory product labelling now uses narrative risk summaries rather than the former letter categories.

History

Attention to special-population dosing grew with the development of renal-function estimation (from creatinine-based formulae toward equations such as CKD-EPI) and with geriatric pharmacology and the Beers Criteria. In pregnancy, regulatory frameworks moved from the older letter-category system toward narrative pregnancy and lactation labelling that better conveys the limits of available evidence.

Debates

How should medications be handled in pregnancy given sparse evidence?

Because pregnant people are usually excluded from clinical trials, evidence on drug safety and dosing in pregnancy is limited; balancing maternal benefit against uncertain fetal risk, and how best to communicate that uncertainty in labelling, remains a persistent challenge.

Key figures

• Sharon Inouye
• Andrew Levey
• Denis O'Mahony

Seminal works

• levey-2009
• inouye-2007
• ags-beers-2023

Frequently asked questions

Why does kidney function matter so much for medication optimization?

Many drugs and their active metabolites are cleared by the kidneys, so when glomerular filtration falls they can accumulate and cause harm; estimating kidney function (for example with eGFR equations) is therefore a key step in tailoring therapy in renal impairment.

Why is evidence on medication use in pregnancy so limited?

Pregnant people are generally excluded from clinical trials for ethical and safety reasons, so much of what is known comes from observational data and pharmacokinetic studies; this is why regulators have shifted to narrative risk summaries rather than simple safety categories.