The Pitt Prescription | Differentiating between dosage forms

The Pitt Prescription is a biweekly blog where student pharmacist and senior staff writer Elizabeth Donnelly provides tips on how to stay healthy in college. This edition was reviewed by Karen S. Pater, PharmD., CDCES, BCACP.

By Elizabeth Donnelly, Senior Staff Writer

Walking into a drugstore aisle can be daunting when there are so many different kinds of medications available for a wide range of ailments. It is difficult to differentiate between the choices if you do not have a solid understanding of how they work or what is best for your condition. 

This is one of the reasons pharmacists are so helpful — they can come out and assist you with choosing the product(s) best fitted to your needs. However, it is also important to have a general understanding of the different products offered so that you can make educated decisions about your health if a pharmacist isn’t available to help you. 

There are many different formulations of medications, some of the most common including liquids, like suspensions and solutions, or solids, like tablets and capsules. There are also other dosage forms known as semisolids, like gels and ointments. Each of these dosage forms have their own individual properties and it’s beneficial to understand the differences. 

What are the definitions of these dosage forms?

Suspension: a solid material dispersed throughout a liquid. This dosage form must be shaken well to resuspend the particles throughout the liquid so that the concentration is properly maintained.

Solution: a liquid in which the medication is fully mixed into the fluid and not a two-phase form like suspensions. This is a uniform liquid formulation. 

Tablets: solid medication (most commonly what people refer to as “pills,” although this is not correct terminology).

Capsules: medication enclosed within a gelatin capsule. 

Pills: small, round solids compounded by hand by a pharmacist. Pills were/are made by using rolling machines and have been replaced by tablets and capsules in modern times, with the exception of a few compounding pharmacies that still produce them under strict guidelines from the Food and Drug Administration. Therefore, most medications are not actually pills and it is not correct to call them such — instead, tablets and capsules are much more accurate. 

Gel: topical medication that is externally used and mixed with a water or alcohol base. These are typically thin formulations you could wash off with water. 

Ointment: topical medication that is externally used and mixed with an oil base. These are typically thicker than gels and much more difficult to remove from the body. 

Important aspects of liquid formulations

Liquid medications, especially suspensions, are most commonly used in children or people who have difficulty swallowing tablets or capsules. Adults can take many common OTC children’s suspensions, like Children’s Tylenol. It is just important to know that you still need to take the correct dose of medication, which likely would end up being a large volume of the children’s suspension.

The best way to measure the amount of medication you’re getting is to use the measuring tool that came with the product, whether it be the cup, a dosing spoon or a syringe. Additionally, you should never use silverware spoons to measure liquid medications, because every kit is different and the sizing of spoons is not universal. Proper dosing is vital, especially when using a suspension or solution in which you need to accurately measure a volume. 

Important aspects of solid formulations

Capsules and tablets come in a variety of different formulations. There are extended-release, delayed-release and immediate-release varieties of many OTC medications. It can oftentimes be difficult to differentiate between products when there are so many choices

Extended-release solids allow the medication to be sustained in the body for a longer duration of time once ingested. Delayed release, on the other hand, is when a solid is coated in a way so that it passes through the stomach before releasing the medication so that the medication is not degraded by stomach acid. Therefore, for people who want a longer duration of coverage, they should choose an extended-release product over a delayed-release one. Additionally, there is immediate release, which is when a medication is not coated or formulated in a special manner and the medication begins to release once it is ingested. There are also rapid release and disintegrating oral medications, and these often act faster than immediate release medications because the active drug is getting released quicker.

Important aspects of semisolid formulations

There are many different semisolid preparations available over the counter. There are creams, ointments, gels and lotions, all of which can be medicinal or cosmetic. While they are similar and are made using various overlapping ingredients, there are some key differences between these formulations. These products, in order of thinnest to thickest, are gels, lotions, creams and then ointments. Gels and lotions typically contain very little to no oil in their base and are quite easy to wash off the body. Creams usually have an even split of oil to water in their bases, and ointments typically are mostly oil-based. The more oil in the base of a product, the harder it is to wash off the body with plain water. 

Gels and lotions are good for conditions where you don’t need a thick coverage and don’t want a lot of oil. An example of a common gel is aloe vera, which many people use for sunburn treatment. Gels and lotions are usually better for people who already have oily skin, especially if they’re using them for cosmetic purposes or rehydration of the skin. Creams and ointments are thicker and contain more oil. Depending on how dry your skin is, a cream may suffice, or if you want extra moisture, then ointments will do the job. One OTC medication that comes in both cream and ointment forms is hydrocortisone, which is used for skin swelling, redness, itchiness and allergic reactions. 

There are many different and potentially confusing factors that come into play when choosing an OTC product. There are so many aspects involved in finding the most appropriate option for you. Ultimately, the best advice is to find a pharmacist and ask for help if you are struggling with choosing an OTC product, because they are the most knowledgeable about this.

Elizabeth writes primarily about self-care and pharmacological topics. You can reach her at [email protected].

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