Liquid dosage forms are pourable pharmaceutical preparations which contain a mixture of drug substance and excipients dissolved or suspended in a suitable solvent or mixtures of solvents. They are designed to provide the maximum therapeutic response in patients who have problem of swallowing solid dosage forms and/or to produce rapid therapeutic effects.
Liquids dosage forms can be solutions or dispersions. Pharmaceutical solutions are clear, homogeneous, and single-phase systems containing one or more drug substances dissolved in one or more solvents, while liquid dispersions can be two-phase or multiphase systems, composed of one phase dispersed through another phase(s). The dispersed phase can be composed of solid particles (suspensions), oil droplets (emulsions), micelles (surfactant solutions), and lipid vesicles (liposomes).
Liquid dosage forms can be administered by oral and parenteral (injectable, inhalation, ophthalmic, otic, nasal, and topical) routes.
This article focuses on the advantages and disadvantages of liquid dosage forms
Advantages of liquid dosage forms
1. Liquid dosage forms (for oral use) are the most suitable dosage form for patients who have difficulty taking tablets or capsules, as might be the case with pediatric or geriatric patients.
2. They are attractive in appearance and gives beneficial psychological effects.
3. Drugs with bitter and unpleasant taste can be given in sweetened, coloured and flavoured vehicles.
4. There is higher flexibility in dosing when compared to solid dosage forms like tablet and capsules. The dose of the drug substance can be easily and conveniently adjusted by measuring a different volume.
5. If given orally, liquid dosage forms are rapidly available for absorption than tablets and capsules.
6. Hygroscopic and deliquescent medicaments which are not suitably dispensed in solid dosage forms can easily be given in liquid dosage form.
7. The products like adsorbents and antacids are more effective in liquid dosage form.
8. The liquid dosage form is expected for certain types of products like cough medicaments
Disadvantages of liquid dosage forms
1. Liquid dosage forms are usually more susceptible to chemical degradation when compared to solid dosage forms.
2. They are bulky and therefore inconvenient to transport and store.
3. Accidental breakage of the container results in loss of whole dosage form.
4. The shelf-life of a liquid dosage form is often much shorter than that of the corresponding solid preparation due to low stability.
5. Solution often provides suitable media for microbial growth and may, therefore, require the incorporation of a preservative.
6. Liquid dosage forms e.g., vaccines may require special storage conditions
7. The taste of a drug which is usually unpleasant is always more prominent when in solution than in a solid form.
8. There is a higher chance of dose variability since the delivery of the dose depends upon the patient measuring the proper volume. This can be significant issue for vision-impaired patients, patients with arthritis, or patients unable to read the numbers on an oral dosing syringe or medicine cup.
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