When you are ill, you take over-the-counter medications or prescription medications, depending on your illness. In both situations, your recovery depends on the efficacy of the medicine. This, in turn, depends on several factors. Some depend on the formulation and form of delivery of the medicine. Others rely on you—the condition of your body and your behavior. Understanding these factors will help you ensure that you maximize the effectiveness of medications.
Bioavailability of Medicine
Bioavailability means the speed and extent of the entry of the active ingredient of medicine into the circulatory system, enabling it to reach the target site for treatment. Part of the process is the absorption of a drug in the body.
Different methods of medication delivery affect bioavailability. The highest rate of bioavailability is achieved with intravenous (IV) administration. This is followed by intramuscular injection, rectal administration, oral medications, and topical applications.
IV administration directly introduces the medicine into the circulatory system without the need for absorption. This is used in emergency situations or when the patient is unconscious. It is also used when there is no oral form of the medicine or if the patient has problems in the gastrointestinal tract.
Medicines taken orally are most common because they are non-invasive and, therefore, patients prefer them. They are also more convenient to take and are more affordable. Compliance with the regimen then increases.
According to an article in Frontiers in Pharmacology, oral medicines have an estimated 90 percent share of the total global market of pharmaceutical products for humans. They make up about 84 percent of the top-selling medications with a market value of $35 billion. The sector is growing annually at a rate of 10 percent.
Compared to IV-administered medicines and injectables, oral medications have to go through the gastrointestinal system, and there are many barriers to bioavailability. They must infiltrate the epithelial membrane of the intestine to reach the circulatory system. Many factors come into play. The gastrointestinal fluid develops an acidic pH when it is empty of food, and this is not a suitable environment for medicines that become unstable in low PH. On the other hand, the presence of food also affects bioavailability depending on the type of medicine and the type of food. The absorption of medication can be accelerated or delayed.
The patient’s specific characteristics likewise affect a medication’s bioavailability. This includes age, weight, level of physical activity, and sex. Other variables are stress, previous gastrointestinal surgery, and existing conditions such as malabsorption syndrome.
Scientists continue to do research and development not only on new medicines but also on ways of delivery to increase bioavailability, especially for oral medications. A study published in February 2021 recommends the use of nanocarriers along with effective and safe inert ingredients for pediatric oral medicines. Another study published in May 2021 shows the development of a pill with built-in chemical microstirrers that generate microbubbles, enabling faster dissolution, dispersion, and bioavailability without damaging the stomach.
Regular doses of medication are given to the patient to achieve steady-state concentration at a level that has a therapeutic effect. This usually occurs only after about four or five doses or four to five half-lives of the medicine. A half-life refers to the period wherein the body has eliminated half of the medicine. After four to five doses, the body retains the same amount of the medicine even between doses.
When a patient needs to achieve steady-state concentration quickly, a higher dose is given at the start of treatment. This dose must be close to the steady-state concentration so that the therapeutic effect begins earlier.
Steady-state concentration is affected by the patient’s drug clearance or the rate at which the body eliminates the medicine from the system. This, in turn, is affected by body weight, metabolism, excretory functions, and other medications. A person with kidney problems, for instance, has a low rate of urinary excretion and, therefore, retains a higher steady-state concentration of drugs. The doctor will adjust the medicine’s dosage as required.
Working with Your Medication
It is vital to work with your doctors and your medications to address any illness properly. If you trust your doctor, you know that the prescribed medicines are the most appropriate ones for your condition to the best of his or her knowledge. Do your part by taking the correct dosage at the prescribed times. Follow instructions on whether certain medications must be taken on an empty or full stomach. Not doing these will decrease the active levels of the medication in your system and lower their efficacy. Having these medicines available to us is a privilege. Do not waste this life-enhancing and, at times, life-saving opportunity.