Time-Shifting Medicines


Scientists use the term pharmacokinetics to describe how drugs move through the body over time.

This movement is influenced by the physical and chemical properties of the drug as well as how the recipient’s body acknowledge the administered pharmaceutics.

Pharmacokinetics is a system of processes that includes liberation, absorption, distribution, metabolism and excretion (collectively known as LADME). It is in these processes that the drugs travel, progress and interplay with the body’s physiology. For the medicine to take effect, it must reach a certain concentration level in the bloodstream. LADME determines when the drug will appear in the bloodstream, the time it will take effect and how long will remain circulating.

Initially, the drug is delivered to the human system through routes either Enteral - oral, sublingual and rectal - or Parenteral - intravenous, intra-arterial, intra-thecal, intramuscular and subcutaneous injections, topical (through eyes, skin, and intra-vaginal), and inhalation.

Once the compounds enter the bloodstream, they travel to different body tissues. The absorption process is influenced by the route of drug introduction, the dosage and chemical properties of the drug, and how the body deals with the drug. Biological factors include cellular membrane structure and permeability, the drug’s binding affinity to bodily proteins, circulatory blood flow, and gastric emptying times that affects medications taken orally.

Drugs introduced through parenteral route do not go through absorption; the full dosage supplied is readily available to be utilized. While drugs given through enteral routes will suffer from incomplete absorption as the some medicine will already be metabolized by the liver before the entire dose reaches the bloodstream. Bioavailability is the ratio of the the amount that reached the bloodstream to the drug’s dose. It affects the drug’s half-life in the body. Reduced bioavailability leads to lower drug efficiency.

As the medicine compounds circulate through the bloodstream, they pass through the liver where they might be metabolized and the liver where they are subject to removal for excretion. Kidneys can eliminate water-soluble compounds whether or not they have been chemically altered (metabolized) in the body. The kidneys have a tougher time with fat-soluble compounds. The kidneys will eliminate the by-products in the form of urine and the liver, aided by the bile, through feces.


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