Rheological Studies on Different Oily Vehicles for Pharmaceutical Preparations

Omran M. Alhamami, Najah R. Hadi, Ashok K. Shakya, Najah H. Al-Janabi, Mosa O. Alhamami


Aims: The rheological properties of oily vehicles based on patents of non-aqueous vehicles for pharmaceutical suspensions were studied. The effects of different concentrations of suspending agents and different excipients on the flow curves were also investigated.

Methods: A Rotovisko viscometer (Haake) fitted with concentric cylinder sensors, NV measuring head– 500 and a temperature controlled water jacket at 37 0C was used.

Results: The results showed that Fractionated Coconut Oil (FCO) alone and with 0.7% w/v lecithin exhibited Newtonian behavior. Dispersions of aluminium stearate, hydrogenated castor oil, Cab-o-sil and sucrose in FCO exhibited pseudoplastic behavior. Aluminium stearate 1% w/v and above and the oily vehicle containing aluminium stearate, hydrogenated castor oil, lecithin and sucrose exhibited thixotropic pseudoplastic properties. The omission of lecithin from the later vehicle resulted in a decrease in the apparent viscosity and the loss of thixotropy.

Conclusion: The thixotropic pseudoplastic behavior of oily vehicles is a desirable property in liquid pharmaceutical systems that ideally should have a high consistency in the container, yet pour or spread easily after they had been stirred vigorously. Possible reasoning and suggestions were discussed.


Fractionated Coconut Oil (FCO), rheology, thixotropy, pseudoplastic behavior, Newtonian behavior.

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