L4 Clinical Pharmacokinetics Flashcards
What is an undesirable experience associated with the use of a medical product in a patient?
Adverse drug event (ADE)
What are three common types of drugs associated with ADEs?
- Pain medications
- Anticoagulant/anti-platelet agents
- Oncology drugs
True or false - all ADE are allergies.
False - all allergies are an ADE, but not all ADE are allergies.
Where do dosing standards come from?
Population pharmacokinetics
What describes how the drug gets into the body from the site of administration?
Absorption
What is the fraction of administered drug that reaches systemic circulation unchanged?
Bioavailability
The area of the body and perfusion affects ___.
Distribution (will the drug reach its target?)
What are some physiologic barriers to distribution?
- Protein binding (albumin)
- BBB
- Eye
- Bone
Calcium is often measured based on albumin levels, as ___% of calcium is bound to albumin. If albumin is low, what can happen?
80; the calcium level can appear falsely low
How do you correct the calcium level for low albumin?
= measured calcium + 0.8(4 - albumin)
What describes how a medication is broken down to less active, more water soluble by-products?
Metabolism
What is the primary site of metabolism?
Liver
Describe Phase I metabolism broadly.
Involves reduction, oxidation, and hydrolysis with CYP450 systems
Describe Phase II metabolism broadly.
Involves GAS (glucuronidation, acetylation, sulfation)
Elimination directly affects ___.
Half life
Most drugs undergo ___ elimination.
Renal
What is normal creatinine clearance?
70-100 mL/min
True or false - you must also adjust for fecal/biliary elimination.
False - these are less common.
What are four broad factors that affect elimination?
- Age
- Disease states (renal failure)
- Hemodialysis/hemofiltration
- Medication
True or false - renal function decreases with age.
True
True or false - creatinine levels increase with age and creatinine clearance decreases.
True (muscle breaks down)
What are some pharmacokinetic variations in neonates?
- Immature skin leads to increased skin hydration and increased absorption of topical products
- Increased ECF leads to increased volume of distribution of water-soluble drugs
- Metabolic pathways mature at different times
- Immature kidney function
What are some pharmacokinetic variations in people who are elderly?
- Skin thinning leads to increased absorption of topical products
- Increased adipose tissue leads to increased volume of distribution of fat soluble drugs
- Decreased ECF leads to decreased volume of distribution of fat soluble drugs
- Decreased GFR
Dose adjustments are most accurate when made at ___.
Steady state
What are the 4 types of drug interactions?
- Drug-drug
- Drug-nutrient
- Drug-disease state
- Level of drug action or organ system
What are two types of drug interactions that affect absorption?
- Chelation
2. Changes in stomach pH
What are three types of drug interactions that affect distribution?
- Competition for binding sites
- Changes in protein binding due to disease states
- Changes in ECF or adipose tissue
What are two types of drug interactions that affect metabolism?
- Induction of CYP450 (increase metabolism)
2. Inhibition of CYP450 (decrease metabolism)
What are two types of drug interactions that affect elimination?
- Competition for elimination pathways
2. Decreased or increased elimination
