Pharmaceutical Syrups: Definition, Composition, Preparation Methods, Evaluation, and Importance in Pediatric Dosage Forms

Definition

Syrups are concentrated aqueous solutions of sugar or sugar substitutes containing one or more active pharmaceutical ingredients (APIs). They are oral liquid dosage forms intended for systemic or local therapeutic effects. Syrups are especially useful for children, elderly, or patients with difficulty swallowing solid dosage forms.

A syrup is a concentrated, viscous, aqueous preparation of sugar or sugar substitutes, with or without medicinal substances, suitable for oral administration.

 

Composition of Syrups

Syrups generally consist of the following components:

1. Active Pharmaceutical Ingredient (API): Therapeutic agent providing pharmacological effect.
2. Sugar / Sweetening Agents: Sucrose is commonly used; alternatives include glucose, sorbitol, or artificial sweeteners for diabetic patients.
3. Solvents: Primarily purified water; sometimes alcohol or glycerin is added to improve solubility.
4. Preservatives: Prevent microbial growth (e.g., sodium benzoate, methylparaben).
5. Flavoring Agents: Improve palatability for children (e.g., orange, cherry, vanilla).
6. Coloring Agents: Enhance appearance and patient acceptance.
7. Viscosity Enhancers / Thickeners: Improve consistency and mouthfeel (e.g., tragacanth, acacia).
8. Buffering Agents / pH Adjusters: Maintain chemical stability of the API.

 

Preparation Methods of Syrups

Syrups can be prepared using several methods depending on solubility of the API and desired properties.

A. Simple Solution Method

• Dissolve sugar in water with gentle heating.
• Add API if soluble.
• Add flavoring and preservatives.
• Cool and fill into bottles.

B. Solution by Heat Method

• Heat water and sugar to form concentrated solution.
• Dissolve API in the solution.
• Add preservatives, flavor, and color after cooling.

C. Agitation Method (Cold Process)

• For heat-sensitive APIs.
• Dissolve sugar in cold water.
• Slowly add API with continuous stirring.
• Add flavor and preservative.

D. Extract or Infusion Method

• Used for herbal or plant-based syrups.
• Prepare extract or infusion from plant material.
• Mix with sugar solution and preservatives.

 

Evaluation of Pharmaceutical Syrups

Quality control ensures safety, stability, and patient compliance. Key evaluation parameters include:

Parameter	Purpose / Description
Appearance	Uniform color, clarity, absence of particulate matter.
Viscosity	Ensures proper flow and mouthfeel.
pH Measurement	Stability of API and palatability.
Density / Specific Gravity	Confirms uniform concentration.
Refractive Index	Ensures correct sugar concentration.
Assay / Drug Content	Confirms accurate API concentration.
Microbial Limit Tests	Ensures absence of harmful microorganisms.
Sedimentation / Precipitation Check	Ensures stability during storage.
Organoleptic Evaluation	Taste, color, odor acceptable for pediatric use.

 

Importance of Syrups in Pediatric Dosage Forms

Syrups are preferred dosage forms for children due to several advantages:

1. Ease of Administration: Easy to swallow compared to tablets or capsules.
2. Accurate Dosing: Oral syringes or measuring cups allow precise dose administration.
3. Enhanced Palatability: Sweeteners and flavors improve compliance.
4. Flexible Formulation: Can be formulated with multiple drugs, vitamins, or minerals.
5. Rapid Onset of Action: Oral liquids can be absorbed faster than solids in certain cases.
6. Customizable Strengths: Concentration can be adjusted according to age or weight.
7. Reduced Choking Risk: Safe for young children who cannot swallow solid forms.

 

Advantages of Syrups

• Non-irritant and generally safe for children.
• Good chemical and physical stability.
• Can mask unpleasant taste of bitter drugs.
• Provides flexibility for multi-drug formulations.
• Convenient for patients with swallowing difficulties or tube feeding.