A Short Note on Liquids

Liquid dosage forms are those forms of drugs that are pourable medicines. They contain a mixture of more than one drug, either in the dissolved or suspended form, in an appropriate solvent. The formulation of liquid dosage forms was found to be the best alternative option for those who had problems swallowing medication. It has rapid therapeutic effects after consumption. 

Liquid dosage forms are ready-to-use medications without any suspended drugs in the solvent. The oral and parenteral routes for liquid dosages are injectable, otic, nasal, inhalation, ophthalmic, and topical. 

Types of Liquid Dosage Forms

Based upon the broad classification, liquid dosage forms are of two types: monophasic and biphasic.

Monophasic 

Monophasic is the single-phase system of liquid dosage form, which contains two components i.e. solute and solvent of the solution. It is one of the simplest and most effective ways of medication as it quickly absorbs medicinal products.

Classification of Monophasic Liquid Dosage Forms

The monophasic liquid dosage form is further distinguished into the following forms: 

• For oral uses: This liquid dosage form consists of a single-phase pourable medication drug for oral application. This pharmaceutical formulation is available in the following examples:

• Mixture: The mixture is the form of liquid dosage that is prepared for liquid oral consumption by mixing more than one drug in either insoluble or suspended form. These mixtures are freshly prepared for short-term health problems like cough, diarrhoea, constipation, etc.
• Linctuses: Linctuses are the liquid dosage forms prepared from more than one medication dissolved in a vehicle with a higher value of sucrose. It is of viscous oral liquid. This medication can be consumed in small doses and needs to be trickled down the throat in undiluted form.
• Draughts: Draughts are an older type of liquid dosage used for medication in the form of large doses. Every dose must be kept in separate bottles, just like the traditional technique.
• Elixirs: Elixirs are different from other liquid dosage forms in flavour as they have a sweet, clear, and hydroalcoholic liquid dosage form. The presence of hydroalcoholic enables the liquid dosage to be water-soluble. The liquid-soluble oral medication makes it different from syrups.
• Syrups: Syrups are the concentrated aqueous solution consisting of more than one sugar component in the liquid dosage form. They contain approximately 66.7% W/W concentration of sugar.
• Drops: Drops are such a liquid dosage form in which a potent drug was administered to the patient in small calculated doses with the help of the dropper suitably. 
• Liquid dosage form for external use: In liquid dosage form for external use, the drug is administered to the patient externally. Examples of the given dosages are lotions, liniments, etc. 
• Liquid dosage form for special use: In liquid dosage form for special use, the drugs are potentially consumed differently from oral consumption. The consumption of drugs is in small doses. Examples of the same are mouthwashes, nasal drops, ear drops, douches, enemas, inhalation, aerosols, etc.
• Liquid dosage for parental solutions: In liquid dosage forms, the drug is administered into the patient’s body by injecting a specific amount according to the particular health problem.

Biphasic

In biphasic liquid dosage forms, the drug is prepared in two phases of the solution. The two phases are solid and liquid. When the liquid dosage form is used for internal use, it is termed suspension. When it is used for external use, then it is called emulsion.

Advantages and Disadvantages of Liquid Dosage Forms 

Advantages

• Liquid dosage forms are quite helpful for patients who suffer from swallowing the medicine.
• The rate of absorption of liquid dosage is relatively better than the solid dosage.
• It is quite flexible as it can be consumed in several doses.

Disadvantages

• Liquid dosages require a lot of storage capacity.
• It can be easily affected by microorganisms due to its sweetness. 
• It will be wasted if the container in which it is kept breaks.

Conclusion

Liquid dosage forms are pourable medicines which contain a mixture of more than one drug, either in the dissolved or suspended form, in an appropriate solvent. They are classified into monophasic and biphasic, which are further divided into specific types. The article confirmed that linctuses, mixtures, draughts, elixirs, syrups, and drops belong to the category of the monophasic liquid dosage form, while suspension and emulsion belong to the biphasic liquid dosage form. Liquid dosage forms are the best alternative due to their consumption, rapid effectiveness, and flexibility in the number of doses. However, its higher storage capacity and need for careful handling may prove to be disadvantageous.