Difference Between Syrup and Suspension (With Table)

Medicines are available in many forms for human consumption. Some of them are tablets, capsules, syrups, suspensions, emulsions, injections, lozenges, etc. These are taken based on the compatibility of patients. Tablets and syrups are the most common dosage forms. While tablets are suitable for the adult age group, children and the elderly are given liquid dosage forms such as syrup or suspension based on patient compatibility. 

Syrup vs Suspension

The difference between syrup and suspension is that syrup is a solution consisting of sugar that is readily dissolvable in other solvents, while the suspension is a biphasic liquid system containing insoluble solute particles in the liquid medium. The drug is completely soluble in syrup, while suspension consists of solid particles in the liquid phase.

A syrup is a liquid dosage form consisting of sugar and active pharmaceutical ingredient being completely soluble in it. Syrups are a clear monophasic liquid system consisting of a homogeneously mixed active ingredient. The sugar in the syrup helps to increase the palatability of the formulation.

Suspension is a biphasic liquid dosage form consisting of particles that are not completely soluble in the liquid media. The particle size for suspension is greater than 1 μm. The particles are in motion as such that they can settle down in a bottle and can be re-dispersed when shaken. The distribution of the drug or the active pharmaceutical ingredient should be uniform when the suspension is shaken.

Comparison Table Between Syrup and Suspension

Parámetros de comparación SyrupSuspension
DefiniciónMonophasic liquid dosage form consisting of sugar and active pharmaceutical ingredient which is completely soluble in it.Biphasic liquid dosage form consisting of particles that are not completely soluble in the liquid media.  
Solvent systemSyrups can be aqueous-based or alcoholic syrups (called elixirs).Suspensions are usually water-based systems.
Ideal paraYoung children and the elderly are more compatible with syrup due to the sweet taste.Ideal for diabetic patients who cannot administer syrup due to the presence of sugar.  
EtapasA monophasic dosage form as the drug is completely dissolved.A biphasic dosage form as the solid particles are not completely dissolved.
Types (based on usage)Simple syrup, medicinal syrup, elixirs, flavoured syrupOral suspension, parenteral suspension, topically applied suspension(creams, lotions).

What is Syrup?

A syrup is a solution consisting of sugar and an active pharmaceutical ingredient completely dissolved in it. This solute is completely dissolved in the solvent, and the resulting mixture is called a solution which is homogeneous in nature. This is the most convenient way of administering drugs in a liquid dosage form. The patients can easily administer it without any shaking requirement.

The solute particles are evenly distributed throughout the solvent system. This is one of the major advantages of this formulation. 

Syrups can be aqueous-based systems or alcohol-based systems. The alcohol-based syrups are known as elixirs. Some syrups are incorporated with a high amount of sugar to increase palatability (in cases where the drug has an inappropriate taste). This helps in the administration of medication to children with ease.

Syrups can be of different types. The simple syrup is a sucrose solution having a concentration of 66.66% sucrose in water (e.g., Syrup USP). Flavoring syrups are syrups having specific flavored substances to give a different taste (e.g., Cherry Syrup). The syrups to which an active pharmaceutical ingredient has been added is known as a medicinal syrup (e.g., Guaiphenesin Syrup).

What is Suspension?

Suspension is a colloidal system having solid particles undissolved in the liquid phase. The particle size of the solid particles in suspension is in the range of 1 μm. The solid particles are suspended in the liquid medium, making it difficult for the drug particles to dissolve completely in the media. The solid particles here are in continuous Brownian motion, which helps the particles to be suspended in the media.

The solid particle in the suspensions is subjected to different kinds of external forces like Brownian motion, gravity, attraction, and repulsion forces. These forces are responsible for the movement and settling down of the particles. After the settling of particles, the two distinct layers can be seen, the bottom layer being more concentrated. This is the reason that suspensions are needed to be shaken before administration so that the particles get evenly distributed. All the suspensions have the instruction on their label: Shake well before use. 

The suspension is a biphasic dosage form. The two phases are the internal phase and the external phase. The internal phase consists of the insoluble solid particles, while the external phase consists of the solvent front. The external phase is also known as the suspending medium. There are two types of suspension: flocculated and deflocculated.

Main Differences Between Syrup and Suspension

  1. The syrup is a sugar solution consisting of uniformly distributed active pharmaceutical ingredients or drugs, while the suspension is a heterogenous mixture where the drugs are not completely dissolved in the liquid media.
  2. The solvent system can be aqueous or alcoholic, while suspensions are usually aqueous-based.
  3. Both of them are administered to children and the elderly, but syrups cannot be taken by diabetic patients while suspension can be used by them.
  4. The syrup is a monophasic liquid dosage form, while the suspension is a biphasic liquid dosage form.
  5. The syrup contains evenly distributed drug particles, while suspension consists of insoluble solid drug particles.
  6. The syrup doesn’t require shaking before administration, while suspension requires shaking for re-dispersion of particles.

Conclusión

There is an abundant dosage form available in the market. While choosing a specific dosage form for the patient, the doctor must have knowledge of all the available options, and the formulator must have a sound knowledge of each and every dosage form.

Syrups and suspensions both are liquid dosage forms containing active pharmaceutical ingredients. The syrup is a homogenous mixture, while the suspension is a heterogeneous mixture of solids in liquids. Syrups being sweet are more compatible for patients as they mask the bitter taste of the drug. Suspensions are also flavored and are often used for drugs that are insoluble in aqueous media.

Referencias

  1. https://adc.bmj.com/content/98/9/725.short 
  2. https://jamanetwork.com/journals/jama/article-abstract/309326