Syrup, Types & Preparation of Syrup: Pharmaceutics

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Pharmaceutical Syrup

Definition

Syrup is a saturated or concentrated, viscous aqueous solution of sucrose or a sugar substitute, with or without flavoring or medicinal substances, prepared in purified water.

Technical Specifications

USP Standard

85% w/v (65% w/w)
Specific gravity: 1.313

IP / BP Standard

66.7% w/w

Table Of Contents
  1. Pharmaceutical Syrup
  2. Comparison: Simple Syrup IP vs. USP
  3. Composition of Syrup
  4. Types of Pharmaceutical Syrups
  5. Advantages of Syrups
  6. Methods of Preparation of Syrups
  7. Formulation of Syrup
  8. MCQs: Pharmaceutical Syrups
  9. FAQ on Pharmaceutical Syrup
  10. 📢 Join Our Pharma Community

Comparison: Simple Syrup IP vs. USP

FeatureSimple Syrup (IP)Simple Syrup (USP)
Concentration66.7% w/w solution of sucrose85% w/w solution of sucrose
PreparationPrepared by hot processPrepared by cold process
Process MonitoringCan be checked using saccharometerCannot be checked during process
CompositionContains Invert sugar (due to heat)Contains pure Sucrose
StabilityMore stableLess stable

Composition of Syrup

Most syrups consist of the following essential components alongside purified water and active drugs:

🍬

Sweetening Agents

Usually sucrose or sugar substitutes to provide sweetness and viscosity.

Sugar-free alternatives: Sorbitol, Saccharine, Aspartame.
🛡️

Preservatives

Antimicrobial agents used to prevent microbial growth.

🎨

Flavor & Color

Flavorants and colorants are added to improve palatability and aesthetics.

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Additives

May contain solubilizing agents, thickeners, or stabilizers as needed.

ℹ️ Preservative Note

Glycerin, methylparaben, benzoic acid, and sodium benzoate are used to prevent bacterial and mold growth. Commonly used antimicrobial agents include:

  • Glycine & Benzoic acid (0.1%–0.2%)
  • Sodium benzoate (0.1%–0.2%)
  • Paraben combinations: Methylparaben, propylparaben, and butylparaben
  • Alcohol

Types of Pharmaceutical Syrups

1. Simple Syrup

A saturated or concentrated, viscous aqueous solution of sucrose in purified water only.

IP Formulation: Sucrose 66.7g, Water q.s. 100g.
USP Formulation: Sucrose 85g, Water q.s. 100mL.

2. Medicated Syrup

Contains medicinal substances. Examples include cough syrup and Ginger syrup.

Example (Ginger): Strong Ginger tincture 5mL, Syrup q.s. 100mL.

3. Flavoured Syrup

Syrups containing flavoring agents but no medicinal substances.

Examples: Cherry and Raspberry syrup.

Advantages of Syrups

  • Antioxidant: Sugar partly hydrolyzes into dextrose and levulose, preventing decomposition of many substances.
  • Preservative: Exerts high osmotic pressure to prevent growth of microorganisms like bacteria and fungi.
  • Palatable: Acts as a palatable sweet vehicle for bitter or nauseous substances[cite: 30].
  • Stability: Prevents the decomposition of many vegetable drugs.
Illustration of three types of pharmaceutical syrups: simple syrup being poured, a medicated syrup bottle, and a flavoured syrup bottle with cherries
Types of pharmaceutical syrups: simple, medicated, and flavoured varieties with examples shown

Methods of Preparation of Syrups

1. Solution with Heat

Suitable for non-volatile, heat-stable constituents.

  • Heat purified water to 80–85°C.
  • Add sucrose with vigorous agitation.
  • Add heat-stable components, then cool.
  • Incorporate heat-labile agents after cooling.

Examples: Syrup IP, Acacia Syrup NF, Cocoa syrup NF, Tolu Syrup IP.

2. Solution by Agitation

Used for heat-labile substances to avoid degradation.

Sucrose and ingredients are dissolved in purified water via agitation without heat.

Example: Sulphate syrup.

3. Addition of Sucrose

Commonly used with fluidextracts or tinctures.

Addition may cause precipitation of alcohol-soluble materials due to dilution.

Example: Aromatic eridictyon syrup NF.

4. Percolation (Cold Process)

Purified water or medicated liquid is passed slowly through a bed of crystalline sucrose.

  • Sucrose is placed in a percolator.
  • Liquid is allowed to pass through the sucrose bed.
  • Adjust final volume with purified water.

Example: Ipecac syrup.

Understanding Inversion of Sugar

Invert sugar: When heat is used in the preparation of syrups, inversion of a slight portion of the sucrose (a disaccharide) into monosaccharides, dextrose (glucose), and fructose (levulose) by hydrolyzation process. This hydrolytic reaction is referred to as “inversion,” and the combination of the two monosaccharide products is “invert sugar.”

Sucrose solutions are dextrorotary, but, as hydrolysis proceeds, the optical rotation decreases and becomes negative when the reaction is complete. The rate of inversion is increased greatly by the presence of acids; the hydrogen ion acts as a catalyst in this hydrolytic reaction.

Fructose is responsible for the darkening of syrup.

Invert sugar is more readily fermentable than sucrose and tends to be darker in color. But, its two reducing sugars prevent the oxidation of other substances..

Chemical reaction: Sucrose hydrolysis into glucose and fructose

Formulation of Syrup

💧

1. Vehicle

Purified water is primarily used to prepare all pharmaceutical syrups.

🧪

2. Additives

Chemical Stabilizers

Glycerin, sorbitol, and propylene glycol are added in small quantities to prevent the crystallization of sucrose.

Colouring Agents

Coal tar dyes, such as Amaranth, Tartrazine, and Green S, are commonly used.

Flavouring Agents

  • Tincture: Lemon, ginger.
  • Fruit Juice: Raspberry juice, wild cherry.
  • Essence: Vanilla, orange.

Preservatives

Benzoic acid and its derivatives, sodium benzoate, and methylparaben are used to prevent microbial growth.

📦 Storage Requirements

Syrups should be stored in dried, well-closed containers in a cool, dark place (not exceeding 25°C).

Note on Crystallization: Syrups may be subject to crystallization during storage, which can cause the container cap to lock. Glycerin, sorbitol, and propylene glycol are added to prevent this.

Note on Fermentation: Syrups may develop a dark color due to the fermentation of sugar.

MCQs: Pharmaceutical Syrups

1. Syrup is a concentrated aqueous solution of:
2. Simple syrup contains how much sucrose as per IP?
3. Specific gravity of simple syrup as per USP is:
4. Simple syrup IP contains:
5. Which of the following is a sugar-free syrup substitute?
6. In medicated syrup, the syrup contains:
7. Which is an example of medicated syrup?
8. Flavoured syrups are also known as:
9. Example of flavoured syrup is:
10. Syrup acts as antioxidant because sugar hydrolyzes into:
11. Which method of preparation involves heat?
12. Inversion of sugar produces:
13. The reaction converting sucrose to glucose and fructose is:
14. Which agent accelerates inversion?
15. Fructose is responsible for:
16. Solution by agitation is suitable for:
17. In percolation, purified water is passed through:
18. Glycerin/sorbitol are added to syrup to:
19. Common preservatives in syrup:
20. Ideal storage for syrup:

FAQ on Pharmaceutical Syrup

1. What is a syrup in pharmaceutical preparation?

A syrup is a saturated or concentrated, viscous aqueous solution of sucrose or a sugar substitute with or without flavoring or medicinal substances in purified water[cite: 2].

2. What percentage of sucrose is present in simple syrup as per Indian Pharmacopoeia?

Simple syrup contains about 66.7% w/w sucrose according to the Indian Pharmacopoeia[cite: 3].

3. What is the specific gravity of simple syrup according to USP?

The specific gravity of simple syrup is 1.313 as per the United States Pharmacopeia (USP)[cite: 3].

4. What are the main components of a syrup?

Syrups generally contain sugar or sugar substitutes, antimicrobial preservatives, flavorants, colorants, solubilizing agents, thickeners, and sometimes stabilizers[cite: 32].

5. What are commonly used sugar substitutes in syrups?

Common sugar-free alternatives include sorbitol, saccharine, and aspartame[cite: 32].

6. What are the types of syrups used in pharmacy?

The three main types are simple syrup, medicated syrup, and flavored syrup[cite: 7].

7. What is simple syrup made of?

Simple syrup contains only sucrose (sugar) and purified water[cite: 11].

8. What is a medicated syrup?

A medicated syrup is one that contains a medicinal substance, such as cough syrup or ginger syrup[cite: 20].

9. What is a flavored syrup?

A flavored syrup contains flavoring agents but no medicinal substances. Examples are cherry syrup and raspberry syrup[cite: 25, 26].

10. What are the main advantages of syrups?

They act as antioxidants, preservatives, and sweet vehicles that improve taste and help prevent decomposition of certain drugs[cite: 28, 29, 30].

11. What are the four methods for preparing syrups?

The methods include solution with heat, solution by agitation (without heat), addition of sucrose to a liquid medication, and percolation[cite: 33].

12. When is the hot process method used in syrup preparation?

It is used when ingredients are not volatile and not degraded by heat[cite: 39].

13. What is inversion of sugar in syrup preparation?

It is the hydrolysis of sucrose into dextrose (glucose) and levulose (fructose), increasing reducing sugar content and improving stability[cite: 46].

14. Which agents are used to prevent crystallization in syrup?

Glycerin, sorbitol, and propylene glycol are added in small quantities to prevent crystallization of sucrose[cite: 69].

15. How should syrups be stored?

They should be stored in well-closed, completely filled bottles at a temperature below 25°C in a cool and dark place to prevent crystallization or fermentation[cite: 69].

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