Rapid Precipitation of Drug

Nanoparticles using Ultrasound

By PATIL CHETAN CHANDRAKANT Dissertation submitted to the Faculty of the Indian Institute of Technology Gandhinagar, in partial fulfillment of requirements for the degree of Bachelor of Technology, Chemical Engineering 2014

Advisor: Dr. Sameer V. Dalvi Department of Chemical Engineering Indian Institute of Technology, Gandhinagar

© Copyright by

Patil Chetan Chandrakant B.Tech 2014

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Abstract

Title of Document: RAPID PRECIPITATION OF DRUG NANOPARTICLES USING ULTRASOUND

Patil Chetan Chandrakant,

Bachelor of Technology, Department of Chemical Engineering, 2014

Directed By: Dr. Sameer V. Dalvi,

Department of chemical engineering

The Liquid Antisolvent (LAS) precipitation process for production of

ultra-fine particles has been widely researched for a last few decades.

In LAS process, precipitation of solute is achieved by decreasing the

solvent power for the solute dissolved in a solution. This is done by

addition of a non-solvent for solute called as Antisolvent. The method

is applicable for a wide range of materials such as pharmaceutical

ingredients, inorganic compounds, polymers and proteins. Particle

formation by the Liquid Antisolvent (LAS) method involves two steps:

mixing of Solution-Antisolvet stream to generate superasturation and

precipitation (which involves nucleation and growth by coagulation

and condensation).

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The objective of this work is to develop a better understanding of the

use of LAS for precipitation and stabilization of ultrafine particles of

Curcumin. The process of precipitation of drug nanoparticles through

addition of LAS can be controlled by either controlling the mixing of

the Solution and Antisolvent or by controlling the precipitation i.e.

controlling the nucleation and the growth.

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Acknowledgements

First I would like to express my deep sense of gratitude to my project

guide Dr. Sameer V. Dalvi to give me the opportunity to work on this

project under his guidance. His Guidance, advices and support to my

work were very helpful.

I would also like to thank Ms. Alpana Thorat for helping me throughout

the project providing innovative ideas for the experiments.

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Table of Contents

Abstract 2

Acknowledgements 3

Table of Contents 4

List of Figures 6

List of Tables 7

Chapter 1: Introduction 8

Chapter 2: Theoretical 9-12

2.1 Nucleation 9-10

2.1.1 Primary Nucleation 9

2.1.2 Secondary Nucleation 10

2.2 Growth 10

2.3 Mixing 11

2.4 Induction Time 12

Chapter 3: Experiment 13-14

3.1 Material 133

3.2 Apparatus and Experimental Procedure 133

Chapter 4: Reults and Conclusion 15-18

4.1 Experiment1 155

4.2 Experiment 2 16

4.3 Conclusion 17

References 19

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.

Nomenclature

Symbol Description Units

Qm mixing time ratio Qm

K Boltzmann's constant (1.381×10−23 J/K) K

τmeso mesoscale mixing time (ms) τmeso

Vm molecular volume Vm

k kinetic energy (J) k

Dt turbulent diffusivity constant Dt

Greek Alphabet

Symbol Description Units

γ solution activity coefficient γ

ε energy dissipation rate (W/kg) ε

σ interfacial energy (J/m2 ) σ

ηB viscosity of aqueous solution (cP) ηB

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List of Figures

Figure 1: Shematic of Particle precipitation process

Figure 2: Experimental setup for LAS precipitation method

Figure 3: SEM image for sample 1 for 0 min Figure 4: SEM image for sample 1 for 24 hrs Figure 5: SEM image for sample 2 for 0 min Figure 6: SEM image for sample 2 for 24 hrs

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List of Tables

Table 1: Particle size distribution for sample1 for 0-4 hrs

Table 2: Particle size distribution for sample2 for 0-4 hrs

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Chapter 1: Introduction

Crystallization is one of the important unit operations, which

involves chemical solid liquid separation. It has many

application in pharmaceutical and chemical industries such as

purification and separation of pure active pharmaceutical

ingredients (API) etc. the process of making of solid crystal

from a solution involves such as nucleation, growth and

agglomeration as shown in Fig.1 . The extent o these steps

determines the size of crystal and their distribution.

Since the properties of material affect the other process and

other characteristics of the material itself. Particle size is one

such property, which has huge impact on the reaction

involving the material. So monitoring and controlling the size

of the solid particles through crystallization is very essential.

Pharmaceutical and chemical grade crystalline products

require a narrow range of particle size distribution.

Figure 1: Schematic of particle precipitation process.

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Chapter 2: Theoretical

2.1 Nucleation

Nucleation is the process of formation of initial crystals from a given solution, in which a small number of ions, atoms or molecules become arranged in a pattern, characteristics of a crystalline solid. Hence it forms sites on which additional particles can be deposited

2.1.1 Primary Nucleation

Primary nucleation is the formation of crystals in the initial

stage when no other crystal are present and if present then

are in so small amount that they don’t influence the formation

of new nuclei.

These are further classified as homogeneous and

heterogeneous nucleation. In homogeneous nucleation;

nucleation is not influenced by wall of crystallizer and any

foreign substance. Heterogeneous nucleation includes the

enhanced nucleation because of presence of foreign particles.

For primary nucleation

Where B = no. of nuclei formed per unit volume per unit time Kn = rate constant C= solute concentration C*= solute equilibrium concentration N= empirical exponent

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2.1.2 Secondary Nucleation

Secondary nucleation includes nucleation formation in the influence of microscopic crystals. It occurs because of the fluid shear and other collisions between the already existing nuclei and newly formed nuclei. For secondary nucleation

MTj =Suspension density

K1 = rate constant

2.2 Growth

The solute molecules present near the nuclei formed get attached to the nuclei and hence increases the size of the nuclei resulting into its growth. This happens mainly because nuclei formed are unstable due to super-saturation. The rate of increase of size of the nuclei is known as growth rate. It is influenced by several factors, such as surface tension of solution, pressure, temperature, relative crystal velocity in the solution etc. The Relation between mixing time, induction time and crystal growth time is calculated using Damkohler number: for nucleation

for growth

Low Da suggests that mixing will have minimal effect, while increasing Da increases criticality of mixing. For growth, at low value of Da mixing would have minimal effect on the particle size distribution. For high values of Da, slow mixing and fast nucleation or crystal growth, mixing would impact the particle size distribution since localized concentrations would lead to variable nuclei generation or crystal growth rate throughout the solution

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2.3 Mixing

In LAS precipitation process, mixing generates superasturation which is followed by, nucleation and growth. Accordingly, there are two main time scales associated with the process of particle formation, namely mixing time (τmix) and the precipitation or induction time (τprecipitation)

τm i x = τm e s o + τm i c r o

Qm can also be predicted as follows:

Dt=the turbulent diffusivity (Baldyga et al., 1995),

U= solution velocity,

qo = volumetric flow rate, ν the kinematic viscosity,

ε = energy dissipation rate ( Torbacke and Rasmuson,

2001 and Baldyga et al., 1995).

Qm= relative degree of exchange of material between eddies in a

suspension (Vicum et al., 2004),

contributions of mesomixing and micromixing to the redistribution of

material can be evaluated using Qm

When

In cases where Qm is large and greater than 1, mesomixing controls and if Qm is small and lower than 1, micromixing controls. Consequently, if mesoscale mixing controls the mixing rate, shear

forces (viscous) are the main components controlling the process.

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2.4 Induction Time

Induction time is defined as the time difference between reaching super-saturation and formation of first nuclei in the solution. But because of measurement difficulties in detecting first few nuclei, another modified definition of induction time is developed, as the time needed for the number density (Nm/V) of nuclei to reach a fixed value. This fixed value depends upon the method of detection of nuclei. If the instrument that is used to detect the nuclei is more sensitive the number density taken will be small, however for less sensitive device it would be a greater value. Factors affecting induction time:

Degree of super-saturation: For high super-saturated solution induction time will be less in comparison to solution with less super-saturation. Since in case of high superasturation, there will be more driving force for precipitation because of a bigger change in free energy of solution.

Degree of mixing: For more degree of mixing induction time will be less in comparison to lower degree of mixing.

Antisolvent Solvent ratio: For more Antisolvent degree of precipitation will be higher hence lower will be the induction time.

Temperature of the solution: For higher temperature the degree of superasturation will decrease resulting into higher induction time of precipitation.

Stabilizer: Presence of stabilizer will increase the induction time by reducing the instability of solution. The change in the value of induction time also depends upon the amount of stabilizer added to the solution. For higher amount of stabilizer added, the value of induction time will also increase.

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Chapter 3: Experiment

3.1 Materials

Curcumin,Ethanol (99.8 % pure) were purchased from Sigma-Aldrich Inc. India. All these chemicals were used without further purification. Deionized Millipore water was used as an Antisolvent

3.2 Apparatus and experimental procedure

Figure 2. Experimental Setup for LAS precipitation method

The diagram represent Flowcell having a jacket around its boundary, through which hot or cold liquid can be passed in order to maintain the desired temperature. There are two peristaltic pumps to maintain the continuous flow of Solvent and Antisolvent stream in the Flowcell. At the start of the experiment desired flow rates for the solvent and Antisolvent streams were set on the pumps. Using a chiller temp of the Flowcell was maintained at 1°C, the Flowcell was connected to the Ultrasound probe for ultra-sonication with power of 115 W. for various

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concentrations of Curcumin in the solvent and for various Solvent-Antisolvent ratio experiments were performed using the same set up. Then those sample were tested in LSI3 Beckman Coulter Laser Diffraction machine to check for the Particle size distribution over a period of time.

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Chapter 4: Results and Conclusions

4.1 Experiment 1

5 mg/ml of curcumin was dissolved in EtOH (Solvent)+ Deionized water (Antisolvent) maintaining the Solvent to Antisolvent flow rate at 1:10 resp. Table.1 : Particle size distribution for sample1 for 0-4 hrs

0 min 15 min 30 min 45 min 1 hr 4 hr

mean 0.715 1.073357 20.21273 18.13803 19.8064 19.7912

median 0.500 1.306547 18.63263 17.34808 18.40393 18.10837

d10 0.176 0.134934 5.118763 4.7083 4.90727 4.706263

d50 0.500 1.306547 18.63263 17.34808 18.40393 18.10837

d90 1.659 1.925503 37.35407 32.33.403 36.5329 36.99333

Figure 3. SEM image of sample1 for 0 min reading

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Figure 4. SEM image of sample1 for 24 hrs reading

By the images and the Table we can see that at the beginning when the nucleation just takes place the molecules are very small and the process of nucleation and agglomeration is taking place, but the growth of the particle is not specific as there is no control on the growth of the particles. We can see that that the particles are not stable and they keep on growing till they reach till 30 microns (± 10 microns)

4.2 Experiment 2

5 mg/ml of curcumin was dissolved in EtOH (Solvent)+ Deionized water maintaining the Solvent to Antisolvent flow rate at 1:3 resp. Table2. Particle Sixe Distribution for smaple 2 for 0-4 hrs

0 min 15 min 30 min 45 min 1 hr 4 hr

mean 3.82359 3.223427 5.504133 5.500883 5.753948 6.007013

median 3.315547 2.734123 4.707977 4.90877 5.056284 5.203797

d10 0.706049 0.62808 0.701396 0.652097 0.667331 0.682564

d50 3.315547 2.734123 4.707977 4.90877 5.056284 5.203797

d90 8.00452 6.681507 11.75647 11.47133 12.0.832 12.6653

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Figure 5. SEM image of sample2 for 0 min reading

Figure 6. SEM image2 of sample for 2 hrs reading

The same thing that we observed for the sample one is repeated here but here the particles grew from 3microns to 6 microns even after 4 hrs. Which means for lower flow rate ratio of Solvent-Antisolvent there was better mixing and the particles were well sonicated and growth of the particle was very less as compared to the sample

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4.3 Conclusion

In this work, a Flowcell in combination with ultrasound, has been demonstrated for precipitation of ultra-fine particle APIs by LAS. It has been shown that the use of ultrasound in a Flowcell induces uniform mixing conditions. In the absence of ultrasound, micromixing controls the mixing process and hence it becomes difficult to achieve better control over particle size. However, use of ultrasound improves micromixing and drastically reduces values of Da below 1, which indicates that the process of particle formation is precipitation controlled and a greater control over particle size can be obtained through manipulation of physicochemical properties of the constituent materials.

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References

Liquid antisolvent precipitation and stabilization of nanoparticles of poorly water soluble drugs in aqueous suspensions: Recent developments and future perspective Alpana A. Thorat, Sameer V. Dalvi

Binay K. Dutta N.d. Principles of Mass Transfer andSeparation Processes. PHI learning Private Limited, Eastern Econommy

G.L. Amidon, H. Lennernas, V.P. Shah, J.R. Crison A theoretical basis for a biopharmaceutical drug classification: the correlation of in vitro drug product dissolution and in vivo bioavailability

Controlling Particle Size of a Poorly Water-Soluble Drug Using Ultrasound and Stabilizers in Antisolvent Precipitation Sameer V. Dalvi and Rajesh N. Dave*

Controlling particle size of a poorly water-soluble drug using

ultrasound and stabilizers in antisolvent precipitation Ind.

Eng. Chem. Res., 48 (16) (2009), pp. 7581–7593

J. Dodds, F. Espitalier, O. Louisnard, R. Grossier, R. David, M.

Hassoun, F. Baillon, C. Gatumel, N. Lyczko

The effect of ultrasound on crystallization–precipitation

processes: some examples and a new segregation model

Part. Syst. Charact., 24 (2007), pp. 18–28

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