In order for any drug to do its intended job — relieve pain, kill an infection, etc. — it must be absorbed by the body. This is a process we often take for granted. We simply swallow a pill or receive an injection and wait for the drug to begin working. But there are many factors that can affect drug absorption within the body, some of which may extend your wait time to feel better and become healthier. 

Drugs are generally made up of both active and inactive ingredients. The active ingredients are what actually treat the condition of concern (pain, etc.), while the inactive ingredients, such as the cellulose that makes up a capsule’s outer shell, simply make the drugs easier to swallow. Absorption involves the body breaking down the drug, which separates the active ingredients from the inactive ones and enables the active ingredients to enter the bloodstream. Only then will you begin to benefit from the drug’s effects. 

Specific Factors That Affect Drug Absorption 

These factors can be divided into categories including the drug recipient’s physiological state, the way the drug was manufactured and the method in which it is administered:  

Physiological State 

The state of the recipient’s body influences how a drug is absorbed. Factors include: 

• The drug recipient’s age
  Older people can experience slower drug absorption.

• The type and amount of food in the recipient’s digestive system
  Many drugs are labeled as “take with food,” “take on an empty stomach,” or “can be taken without regard to meals.” 

• The health of the recipient
  Certain gastrointestinal and liver conditions can slow or even prevent absorption of some drugs. 

Drug Manufacturing 

The way a drug is made also affects its absorbability. Factors include: 

• The size of drug molecules (active ingredient)
  The smaller the drug molecules, the faster the rate of absorption will be. 

• The use of protective coatings
  You have probably heard of enteric-coated pills before, but you may not be aware of their purpose. An enteric coating enables a pill to survive stomach acids intact and move to the intestines, where the pill is then absorbed. 

• The density of the drug
  A hard tablet takes longer to absorb than a soft capsule. 

Method of Administration 

In some cases, a physician may want a drug to be absorbed quickly by the patient. In other cases, slow absorption may be more beneficial. Drugs can be administered in a variety of ways, each of which has its own absorption rate. Some typical methods of administering drugs include: 

• Oral – The drug is swallowed. 
• Sublingual – The drug is placed and absorbed beneath the tongue.  
• Topical – The drug is applied to and works on top of the skin. 
• Intramuscular – The drug is injected into a muscle such as a bicep or buttock. 
• Transdermal – The drug is absorbed through the skin.  
• Rectal – The drug is administered as a suppository. 

Learn More in Online Medical Physiology and Pharmacology Programs 

The University of Florida’s acclaimed College of Medicine offers online programs centered on the major human body systems and organs. Depending on which program you choose, you can also take a deep dive into how drugs affect and are processed by the human body. 

Master of Science in Medical Sciences with a concentration in Medical Physiology and Pharmacology 

This program helps prepare you for medical school and related exams such as the MCAT and National Board by exploring the ways drugs impact our major body systems and organs. If you’ve previously completed one of the graduate certificate programs listed below, you may be able to transfer up to 15 credits to this 30-credit program, meaning you’re already halfway done with your master’s degree! Many students finish the full degree program in as little as one year. 

Graduate Certificate in Medical Physiology  

Study the core concepts of medical physiology in this 9- to 14-credit program, which you can complete in as little as one semester. 

Graduate Certificate in Medical Physiology with a specialization in Cardiovascular/Renal Physiology 

Gain a deeper understanding of cardiovascular and renal physiology and pathophysiology research that will prove invaluable in a clinical setting. You may be able to complete this 12-credit program in as little as two semesters. 

Entirely Online, Extremely Convenient  

Each of these programs is delivered in an asynchronous, entirely online format that allows you to complete coursework on your own schedule from practically any location. You can earn a master’s degree or graduate certificate while keeping up with all your professional and personal commitments. 

No GRE is required for admission to any of these graduate programs!  

Hone your mastery of physiology and pharmacology with an online master’s degree or graduate certificate from the University of Florida. 

Sources:
https://www.merckmanuals.com/home/drugs/administration-and-kinetics-of-drugs/drug-absorption
https://www.merckmanuals.com/professional/clinical-pharmacology/pharmacokinetics/drug-absorption
https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/drug-absorption
https://www.healthline.com/health/capsule-vs-tablet
https://www.healthinaging.org/medications-older-adults/medications-work-differently-older-adults
https://www.slideshare.net/jaimini26/factors-affecting-drug-absorption
https://www.news-medical.net/health/What-is-Drug-Absorption.aspx