The significance of pharmacokinetics is hard to understate. The history of pharmacokinetics stretches back over a hundred years and has informed scientists about how drugs affect the body and mind since its discovery.
The pharmacokinetic properties of drugs explain how they interact with the body and can help treatment providers determine the best course of action for helping people overcome substance use disorder.
This article will provide a quick overview of pharmacokinetics, the metabolism of drugs, and how the components of pharmacokinetics can inform addiction treatment.
Pharmacokinetics is the field of study that examines how drugs move and interact throughout the body. The absorption and distribution of drugs are far from simple, and different drugs are metabolized in different ways. Looking at the pharmacokinetics process can help clinicians, and medical providers understand how certain drugs affect people and where they may struggle when attempting to achieve abstinence.[1 ]
Understanding the metabolism of drugs is crucial for medical providers treating people with substance use disorders. It can indicate what organs may have been impacted by drug use, whether certain medications can be administered, and when to expect a return to normalcy after sustained substance use.
Understanding the steps of pharmacokinetics can also help people with substance use disorders understand how substances affect them, which may help them stay sober.
When drugs enter the body, they undergo a “pharmacokinetic phase.” A pharmacokinetic phase has four key components, often called “ADME pharmacokinetics.” ADME pharmacokinetics is an acronym in which the letters are the four steps of pharmacokinetics in a pharmacokinetic phase.
Pharmacokinetics absorption is the first step in the pharmacokinetics process. In this step, substances first enter the bloodstream and begin to have an effect. Absorption in pharmacokinetics starts almost immediately, though the speed of absorption and distribution of drugs into the blood depends on various factors. 
Pharmacokinetics distribution of drugs is the next step in a pharmacokinetic phase. During distribution, drugs that have entered the bloodstream spread throughout the entire body. Blood circulation can carry substances into several different fluids and tissues. 
Pharmacokinetics metabolism is the third step in the pharmacokinetics process. In this step, the body identifies that a foreign substance is present in the bloodstream and begins to break it down into metabolites. Impact factors on the body from these metabolites can often be unpleasant. In the case of alcohol, for instance, the first metabolite causes the symptoms of a hangover.
The last phase of the pharmacokinetics process is excretion. In this step, the inert metabolites are removed from the body through urine, sweat, bile, feces, or respiration. 
Certain drugs will absorb into the bloodstream faster than others, but other factors affect pharmacokinetics absorption as well. This includes:
For example, intravenous drug use allows drugs to be absorbed into the bloodstream almost instantaneously. Also, it takes much longer for a drug to be absorbed when taken orally.
Medication absorption can be affected by specific formulations. For example, many drugs come in “extended-release” varieties, which have specialized coatings that dissolve slowly in the stomach, allowing a sustained drug absorption phase.
Certain factors will affect how quickly drugs are metabolized. These include:
Oftentimes, extended periods of drug use slow the body’s metabolism. This is commonly seen in people with alcohol use disorder, who can lose pharmacokinetic tolerance and appear intoxicated for longer periods.
Excretion is handled primarily by the kidneys. The time it takes the kidneys to excrete 50% of substances is known as the half-life of drugs and varies between substances. The half-life of drugs can be extended due to certain kidney problems, such as renal dysfunction or pathologies that impact renal blood flow.
Pharmacokinetics is important to drug companies and patients for several reasons. They can help:
In essence, the components of pharmacokinetics give providers and patients an idea of what specific drugs or medications will do within the body and help them to choose whether it’s the right choice for them.
Factors that affect pharmacokinetics include:
Pharmacologists interpret this information to uncover how a drug interacts with the body and whether it has any potential benefits or drawbacks.
Pharmacokinetics and pharmacodynamics are two of the three phases of drug action. The third of the three phases of drug action are pharmaceutics, which generally refers to how drugs are manufactured, not how they behave in the body.
Where the pharmacokinetics of drugs explain how drugs interact with the body, pharmacodynamics looks more specifically at a drug’s mechanism of action. Pharmacokinetics doesn’t examine how drugs produce their effects but only concerns the physical action of drugs and metabolites within the body.
For example, looking at how drugs such as alcohol influence dopamine and the brain’s reward network is the domain of pharmacodynamics. The domain of pharmacokinetics examines how alcohol is metabolized and distributed within the body.
At Genesis Recovery, we emphasize understanding how drugs interact with the body, mind, and person. Learning about the specific effects of drugs helps people to understand what addictive substances do and how we can work to change these effects in the process of recovery.
If you or a loved one is struggling with a substance use disorder, reach out to the team at Genesis Recovery to learn more about our science-informed addiction treatment options. From the moment you call, our team will be there to support you in your journey towards recovery.