Authors : Catarina Marramaque (hospital pharmacy resident ) e Joana Simões (pharmacist ) Excipients are all the components that make up a medicine except for the active substance (one or more), which is responsible for the therapeutic effect. They are components without therapeutic effect, but which ensure that a medicine has the appropriate properties to be taken as intended. Why are excipients needed? Most active substances cannot be administered directly , due to their physical, chemical and sensory characteristics. These include: Low solubility : limits the amount of substance dissolved and absorbed in the gastrointestinal tract; does not ensure the homogeneity of mixtures obtained during the manufacturing process, which has a significant impact on therapeutic efficacy. Physicochemical instability : some active substances, when exposed, for example, to light, humidity, heat or oxygen, degrade, and therefore need to be combined with components that protect them from these effects. Sensitivity to pH : the pH of the gastrointestinal tract is not always the same; it is lower in the stomach and higher in the intestines. Variations such as these can contribute to the deterioration of the active substance before it reaches the intended site of absorption. Taste and odor : some active substances have unpleasant tastes or odors, which naturally lead to some resistance to their administration if these characteristics are not masked by other excipients. It is in these contexts that excipients play a key role, by making it possible to administer the active substance . Types of excipients Diluents Increase the total volume of the medicine. Are used when the amount of active substance required to obtain the desired therapeutic effect is very small, which does not allow accurate dosing. Their addition makes it possible to administer the active substance in small amounts, ensuring that the intended dose is effectively delivered. Example: Lactose Binders Bind all the components of the medicine, ensuring, for example, that a tablet maintains its integrity until the moment of administration. Example: Microcrystalline cellulose Disintegrants Promote the disintegration of the oral dosage form (for example, a tablet) after administration. The disintegration process leads to the release of the active substance, facilitating its dissolution and subsequent absorption in the body. Without disintegrants, proper release of the active substance could be compromised and, consequently, treatment efficacy would be reduced. Example: Croscarmellose sodium Lubricants Prevent the medicine from adhering to the surfaces of the equipment used during the production process. Example: Magnesium stearate Surfactants and wetting agents Increase the solubility and dispersion of poorly soluble active substances. Ensure uniform mixtures, which increases the bioavailability of the medicine. Example: Sodium lauryl sulfate Colorants Improve the appearance of the medicine in terms of color and facilitate its identification. Flavorings Improve the taste of the medicine in order to facilitate its administration. They are very common in pediatric formulations. Preservatives Used mainly in liquid medicines (syrups) or semi-solid ones (for example, ointments), to prevent the growth of microorganisms, thereby extending shelf life. Coating Act as protective agents of the active substance against environmental factors (for example, light, humidity, oxygen, pH). Like flavourings, they can also mask unpleasant tastes. Due to their characteristics, coatings can also control the rate and site of release of the active substance. Through all these functions, excipients enable the formulation and administration of the active substance in the desired dosage form. Additionally, excipients may also have other functions that are essential for the manufacturing process, stability, efficacy and acceptability of a medicine. Can excipients be associated with adverse reactions? Although the ideal excipient is an inert compound, some may be associated with possible adverse effects of a medicine. However, according to European Medicines Agency guidelines, these excipients are properly identified on the outer packaging and in the package leaflet of the medicine. For example, when a medicine contains lactose in its composition, this component is highlighted in bold among the excipients. There may also be contraindications for taking a medicine in patients with hypersensitivity to the active substance or to any of the excipients mentioned. Remember: If you have any questions about medicines, including possible adverse reactions associated with excipients, you should contact the prescribing doctor or a pharmacist. Sources European Medicines Agency. Excipients in the labelling and package leaflet of medicinal products for human use . March 2018 Hancock B. What is an excipient? Pharmaceutical Press . December 2024. PE Pharma Excipients. Pharmaceutical Excipients – Some Definition . The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
