Increased Viscosity for Stability of Suspension Preparations

by | May 23, 2023 | Cellulose Ether | 0 comments

Every day you often meet with materials such as honey, oil, lubricants, and syrup, right? The consistency of the honey will be different from that of the syrup. As well as the viscosity of the oil which is different from honey and lubricants. The medicine you take such as liquid drugs is also very concerned about the level of viscosity.

People who cannot take tablets or capsules like children and the elderly usually look for a liquid form of medicine to make it easier for them to absorb nutrients. The manufacture of liquid medicinal preparation is concerned with the level of viscosity in addition to the large sedimentation volume, ease of pouring into serving bottles, dispersibility, and particle size.

The Importance of Suspension Preparations

With the increasing modernity in society, the threat to our health and fitness is raising. People are competing to be at the forefront by minimizing sleep time, adding nutritious intake, and maintaining health with supplements.

They also do exercise as a modern habit. If they are already sick, many people choose drugs that work quickly so that the pain can be cured to return to being productive again as usual. Unfortunately, most drugs are chemically unstable in solution but are stable when suspended.

The manufacture of suspensions is also important for releasing therapeutic properties, storage stability, and releasing aesthetic elements because the preparations usually have an attractive appearance.

So, what does the pharmaceutical industry expect in the manufacturing process of suspension preparations? They expect a suspension that settles slowly and is redispersed when the bottle is shaken. Therefore, it is important to maintain the stability of the suspension to slow down the accumulation of particles.

Various Types of Suspension

You may not always get detailed information about the drugs you are taking. Doctors only prescribe medicines that you have to pay for at the pharmacy. Meanwhile, the pharmacist may only explain how it is used daily and the risks that may arise for long-term use. You better know the types of suspension preparations that you may take home from the pharmacy. So, you can store drugs with a certain viscosity in the proper way.

Suspension preparations consist of three kinds that circle in the market.

  • Oral suspension. This is a liquid medicine that you usually take at least three times a day. This suspension has fine solid particles and is dispersed in the liquid phase using a suitable flavoring material. Since it is consumed by drinking, the viscosity of the oral suspension is adjusted to the suction power of the throat organ. The throat is connected to the sense of smell, so flavoring materials must also be used in this kind of suspension.
  • Suspension for injection. It is a type of sterile suspension in which the preparation is solid and dry with the carrier being adjusted to form a sterilizing solution.
  • Eardrop suspension. The outer ear can be treated using a liquid ear drop suspension containing fine particles. The viscosity of this suspension is different from the oral one. It’s lighter than the oral suspension.

The Effect of Viscosity on The Suspension Preparation

We know that liquid drug preparation should have a viscosity that is not too thick so that the particles they contain can be slowed down and the flow velocity is as required. Suspension stability can be maintained in several ways like the following:

  • Avoid precipitation by reducing the particle size. When the particle size gets smaller, the larger the surface area then the compressive force on the liquid will slow down the movement of the particles.
  • Avoid collisions between particles that can cause a precipitate to form. This can be done by reducing the number of particles or concentrations in a container. If the number of particles is high, the particles will be difficult to move freely. This activity will have the potential to cause high deposition.
  • Last but not least, pay attention to the viscosity of a liquid. The increase in viscosity will affect the downward movement of a particle. When you make suspension preparation with high viscosity, the suspension will be difficult to shake and pour. The purpose of shaking the suspension preparation is to make the preparation redispersed. The viscosity of a suspension should be increased properly so that the particle descent can be slowed down.

Factors Affecting Viscosity

Viscosity is fluid resistance if it receives an external force. Many factors can affect the viscosity of an object such as temperature, cohesive strength, molecular weight, and pressure.


We know that viscosity is inversely proportional to temperature. Heating can make the cohesion between molecules weaken. If the temperature rises, the viscosity will decrease and vice versa. Liquids and gases have different reactions when heating occurs or the temperature increases. 

Rising temperature in a liquid will cause the viscosity level to decrease. While the temperature rises the gas substance will increase its viscosity. 

Cohesive Strength

Viscosity will always be affected by cohesive forces between like molecules in the object. The level of viscosity will be higher if the strength of the cohesive force is greater. 

Molecular Weight

The level of viscosity will be higher if the molecular mass of the object is getting heavier.


Pressure will make the viscosity level of a liquid rise because pressure affects the bonding of liquid molecules. Meanwhile, pressure will not affect the level of viscosity in gaseous substances. 

Viscosity for Quality Control

Each step of the production line urgently requires viscosity measurement. This is done to ensure the consistency of incoming raw materials, verify the consistency of the final product, and provide immediate information about the permeability of a material. 

Suspension dosage products in the pharmaceutical and food industries require stabilization to maintain their quality. The increased viscosity level will help the stability of the suspension preparations as long as the increase is not excessive. How to measure viscous material is to use the workings of a rotational viscometer. The higher the range of viscosity levels, the stronger the spring is needed in rotational viscometer measurements. 

Meanwhile, a single-cylinder type rotational viscometer will be used to measure the viscosity of an adhesive.