An overview of Oral Liquid Formulations

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Homogeneous liquid preparations containing a solution, an emulsion, or a suspension of one or more than one ingredient appropriate for a liquid base are known as Oral Liquid Formulations. These prepared liquids can either be used just like it or maybe when they can be diluted.

The prepared formulation contains several other ingredients, such as flavorings, sweetening agents, and other coloring agents approved for usage. Suppose these preparations are made for pediatric purposes. In that case, their sweetening agents, such as potassium or sodium saccharin, should be restricted to only 5 mg/kg of the child’s body weight.

You should no further dilute the oral liquid after it has already been diluted for the first time, and neither should it be stored unless mentioned in the instructions. The reason for not storing these liquid formulations is that once kept for an extended period, and they can become very unstable. Therefore, it should be used when it is freshly diluted or as mentioned in the instruction manual.

Difference between a vial and an ampoule

When we talk about vials and ampules, one thing common about both of them is that they both require reconstruction. One thing you commonly see lying around on the shelves of the pharmaceutical laboratory is an ampoule or a vial. The vessels used for both have great importance since they have a significant role when preserving and storing liquid, medicine capsules, medicinal fluids, and other contents that you may use for practical pharmaceutical purposes. These are typically used to mix medicines you must deliver to a particular patient. The storage containers generally are glass bottles or sometimes even good-quality plastic ones.

An ampoule

In short words, we can say that an ampoule is nothing but a vial to be consumed in one shot, a single dose with a sealed neck. The ampulla is closed at its neck so that the liquid inside is not contaminated. Breaking the seal of these ampoules is extremely easy and requires no extra effort as it is just a matter of twist, and the sale breaks. Once these ampoules are broken, you cannot reuse them. Important to remember here is that if the liquid needs to be stored or preserved for further use, it can be stored in a sterile vial or thin or slim pins. 

A vial

When we speak of a vial, it is a much broader term than an ampoule. These are multidose glass containers that Store serum, drugs in liquid form, and several other medical compounds. A vail cannot be sealed like an ampule and usually has a screw back on the lid of the container used for storage. You would most commonly see that the container is generally flat on its base, so it can comfortably sit on a platform.

The difference between them

Let’s discuss the difference between an ampoule and a vial based on certain factors:

1. Application: an ampoule is most commonly used for pharmaceuticals, dental, first-aid, spa items, veterinary, Diagnostics, toiletries, health, and beauty aids. At the same time, you can use a vial in industrial applications, scientific sample vessels, research applications, and autosampler devices.

2. Potency protection: storage of chemical compounds that do not remain in good health after exposure to oxygen or any such element is stored in ampoules to keep their potency intact. Manufacturers ensure that the oxygen is sucked out from the ampoule before sealing it, so the solution does not get contaminated. In the case of a vial, since it is not a hermetic type, it is a perfect choice to store stable elements.

3. Re-usage: Ampoules, as we already mentioned, are not reusable after the glass bottle has been broken, whereas, in the case of the vial, you can easily store it for re-usage.A vial can be frequently reused and cleaned since it has a lesser risk of contamination.

4. Volume: Ampoules mostly hold lesser quantities, and since they have to be sealed, there may be chances of some disparity in the volume of medicine or liquid added to them. In the case of the vial, a much more accurate Storage can be done along with useful Visual indicators.

Different classes of oral liquid formulations 

1. Syrups: Syrup is a kind of oral formulation made from more than one ingredient. The base of the syrup is mainly made with large quantities of sucrose, sweetening agents, and sugar, and ethanol is added to the solution as a preservative. Apart from these, syrups also contain antimicrobial agents to maintain the preparation quality.

2. Oral suspension: in most short words, we can say that this is a liquid that contains more than one active ingredient further dissolved in the desired base.

3. Oral drops: these are oral liquids that are prepared to keep in mind the small dosage and usually come with a measuring device commonly known as a dropper.

4. Oral solution: when an oral liquid that contains more than one Active ingredient is further resolved in a particular place, it is known as an oral Solution.

5. Oral emulsion: certain oral liquids contain more than one active ingredient, and these are usually unstable when in the water phase, and once they are oil in water dispersion, they stabilize. You can find dissolved solids in one of the phases or both of them.

6. Mixtures: oral liquids have more than one active ingredient and are dispersed or dissolved in a particular base.

7. Elixir: a flavored and precise solution that contains more than one active ingredient dissolved in a base with high sucrose levels. These liquids may also include either ethanol or its diluted version.

8. Linctus: An oral and viscous liquid that contains either one active ingredient or more than one active ingredient and is further dissolved in a base primarily high in sugar or sucrose.

9. Dry powder suspension: these solutions are made by finely powdering the desired drug and then suspended in a suitable liquid vehicle. These dry powders are further reconstructed using the filtered sterile water that comes with them in the prescribed quantity.

10. Powder: is prepared by mixing given quantities of particular drugs, whether in diluted form or not. Also, if necessary, specific flavoring agents can be added to these respective powders.

   Monophasic Liquid forms

    These are homogenous solutions prepared with active ingredients dissolved in water or other solvents like alcohol, ether, or glycerine. Some of the most commonly known forms are explained as under:

◦ Syrup Essence: These doses are mainly alcoholic forms or sometimes hydro-alcoholic solutions of particular volatile substances. These substances could either be solid, liquid, or gas. When these solutions are in solution form, you can widely use them in treatments or as flavoring agents.

◦ Elixir: These are flavored and sweetened, clear-looking solutions, and these solutions also include active ingredients in them. These may be less sweet and dense than syrups and maintain much more alcohol or water-soluble materials when in solution. On the contrary, these elixirs cannot easily mask the taste or after taste of drugs as efficiently as syrups.

◦ Fluid extracts: therapeutic or drug solutions made from solvent extraction from plant materials are known as fluid extracts.

◦ Gargles or mouthwash: The liquids used for girdles are mostly alcohol-water Solutions which are further medicated mildly to treat any problems that may arise in teeth or gums.

   Biphasic liquid form

These solutions are commonly seen when there is a dissolution of any active ingredients that may eventually not dissolve in any particular common solvent. Widely encountered are emulsions, suspensions, or mixtures.

◦ Oral suspension: oral suspension is a suspension in liquid form that uses active ingredients that are further suspended in a suitable base. As time passes, some solid particles may separate from the solution, and as soon as you reshake, it will redisperse.

◦ Oral emulsions: These solutions are made up of active ingredients that may be very unstable when in the water phase. The part here is that it can stabilize again when in oil-in-water dispersions. Either one step of both can contain any form of dissolved solids. It is also essential to know that both the liquids being used can separate from each other, but when they are shaken, they come back together. The prepared solution is stable and can be made into a homogenous dose once shaken.

◦ Mixtures: when liquid contains Active ingredients, which may be dissolved, all but the suspended in a suitable place is termed the mixtures. Like in oral emulsions, active ingredients can also have a few suspended solids, which you can combine again by retaking them.

• Linctus: These are only active ingredients dissolved in a particular solution that may be high in sugar. The most common usage is cough syrups, and you can take this oral liquid preparation with or without water.    

Advantages of oral liquid formulations

Oral Liquid formulations are a perfect choice for people who find it extremely hard to swallow other forms of medication like tablets. Many additions are made to this liquid formulation, such as stabilizers, preservatives, and vehicles. Apart from these, it also includes emulsifiers, suspending agents, colors, flavors, and solubilizers. Some of the most commonly known benefits of liquid dosage forms are:

1. Oral liquid formulations are a perfect way to get the medicine in one’s body for children and adults who find it extremely hard to swallow medication. These are much simpler in usage as compared to tablets and also capsules.

2. Sweetened and flavored vehicles are a perfect way of masking the unpleasant and bitter taste of the drug.

3. Since its appearance of this is extremely attractive, it provides psychological advantages.

4. The absorption of capsules and tablets is challenging compared to liquid form, which is more straightforward.

5. Antacids and absorbents deliver results when liquid from what they would otherwise do in any other form.

6. A liquid formulation is preferred for particular medications, such as cough syrups.

7. In the case of liquid dosage, they are unstable from the beginning, and the shelf life of these liquid forms is much shorter.

8. Certain liquid formulations, such as vaccines, require storage in liquid form since water cannot be available everywhere.

Requirements for manufacturing units of oral liquids

The premises that need to be made shall be constructed, designed, and maintain in such a way that it precisely suits the manufacturing of a particular liquid. The overall design of the unit should be made to avoid any contamination.

The drainage should also be appropriate and may have good traps to drain any waste.

You should use appropriate materials such as stainless steel, for any part that comes in direct contact with the final product. In this case of manufacturing, minimum to no glass utensils should be used.

Properly having purified water, which is not only monitored regularly but also maintained at certain levels, is extremely important.

Individuals coming in close contact with the oral liquid preparation area should wear proper gear to avoid contamination. Wooden pallets and gunny bags should be restricted to areas where the final product is stored or cleaned. The manufacturing unit should take proper care to maintain appropriate emulsion homogeneity by using suitable suspensions and emulsifiers. The packaging area should always have five filter air supply.


Torque Pharma is a leading company that ensures proper safety while manufacturing oral liquid formulations. Products like Multi power syrups, Azetor -100, Alox antacid, Babysit drops and several others are a range of products the company manufactures. As mentioned before, oral liquid formulations are an excellent way for senior citizens, so children who find taking tablets complicated. In several cases, the consumption of oral liquids has better results since they are absorbed better than pills.

The above explains all about oral liquid formulations.

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