Test your knowledge and check your answers on the second slide.
🚶🏻Think of pharmacokinetics (PK) as the drug’s journey into, through, and out of the body. This journey passes through four phases that can be remembered using the mnemonic ADME or “add me”. ⠀
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-Absorption: the process of the intake of the drug into the body⠀
-Distribution: the process of the dispersion of the drug into the bloodstream and tissues⠀
-Metabolism: the process of the parent compounding into daughter metabolites⠀
-Excretion: the process of eliminating the drug from the body⠀
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🗻 This journey varies depending on patient-specific factors such as renal function, sex, age, and genetics. All of these factors can affect the drug’s half-life, rate of elimination, and distribution and subsequently lead to toxicity or therapeutic failure. Knowledge of pharmacokinetics can assist with adjusting doses correctly especially in drugs that require therapeutic drug monitoring. ⠀
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☝🏻 Additionally, drugs go through different processes of metabolism and elimination called first-order and zero-order kinetics. The biggest difference is that zero-order kinetics undergo constant elimination regardless of the plasma concentration while first-order kinetics depends on concentration. A good analogy is relating the concentration of drug to cake: 🎂⠀
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-Regardless of how big of a cake you are served, you can only eat one bite (a certain amount) at a time, that’s zero-order kinetics (15 mg/hr)⠀
-With first-order kinetics, you suddenly can eat portions of the cake at a time so the bigger the cake the bigger the portion of cake you can eat (eliminate) at a time (50%/hr)⠀