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Journal of Drug Delivery and Therapeutics

Open Access to Pharmaceutical and Medical Research

Copyright  © 2024 The  Author(s): This is an open-access article distributed under the terms of the CC BY-NC 4.0 which permits unrestricted use, distribution, and reproduction in any medium for non-commercial use provided the original author and source are credited

Open Access   Full Text Article                                                                                                                                                     Research Article

Stabilization of the pharmaceutical finished dosages form by using various techniques

Vikas Chandel ¹*, Hemendra Pratap Singh ², Nilesh Rarokar ³, Kamlesh Wadher ⁴

¹ DGM Formulation Development, Anthea Pharma Pvt. Ltd., Hyderabad, Telangana, India

² B N Institute of Pharmaceutical Sciences, B N University, Udaipur, Rajasthan, India

³ G H Raisoni Institute of Life Sciences, Department of Pharmaceutics, Shradha Park, Hingna MIDC, Nagpur-440016, India

⁴ BCYRC’S KDK College of Pharmacy and Research Institute , Nandanvan, Nagpur-440009, India

INTRODUCTION 

The stabilization of pharmaceuticals means that the drug product is physically, chemically and microbiologically stable at the recommended storage condition throughout the predefined shelf life of the product. The physical stability means that the drug product shall retain its original shape, size, color, particle size, globule size and texture throughout the recommended shelf life of the product. The chemical stability means that the drug product and its critical constituents e.g. Active pharmaceutical ingredient(s), preservatives, antioxidants, rate controlling excipients etc. remains within the predefined limits. 

The microbiological stability means that the drug product is not contaminated with the microbes; if the drug product contains antimicrobial preservatives, then these preservatives should be in sufficient amount to prevent the growth of microbes throughout the shelf life of the product. Any changes in any of these parameters should be within the acceptable range as determined during development and finalization of the limits at various stages of product development, filing and approval process. Apart from this the specifications can be modified to some extent during the commercial run of the product, after due discussion and approval from the regulatory agencies.  Stabilization of the pharmaceuticals is one of the most challenging but important task for the pharmaceutical industry this is applicable for drug products which are stable at room temperature as well as the drug products which are stable at refrigerated condition. 

The drug products which are not stable at room temperature but are stable at refrigerated storage condition poses a grave challenge for maintenance of the cold chain during the manufacturing, transportation, storage and subsequent distribution for the end use of the drug product. As per the Pharmaceutical & Medical Packaging News, surveyed supply chain experts in 2015 and concludes these findings that amongst the temperature sensitive products shipped, 51% were ambient, 31% were refrigerated, 17% were frozen, and 32% should not be allowed to freeze¹.

Due to advent of research and development in the arena of pharmaceuticals evolving past traditional chemical based small molecular therapeutics to more complex and more effective large molecular biologics which are sensitive to environmental condition are available as an opportunity to stabilizes from all possible destabilizing phenomenon viz. hydrolysis, Oxidation, Reduction, microbial contaminants, aggregation, etc.^2,3 The exact number of pharmaceutical products affected by prolonged storage and temperature is difficult to pinpoint. The improper exposure to temperature during storage and even in distribution chain may also leads some untoward effect

In August 2017, for instance, a shipment from a single lot of Intralipid 20% IV fat emulsion, 100 mL bags (Baxter International, Inc.), was improperly exposed to subfreezing temperatures which one is outside the labeled acceptable storage range, on its way to a distribution facility. These frozen condition leads to an enlargement of the product’s emulsion droplets and forming aggregates that can obstruct pulmonary circulation, leading to serious health problems and possible death⁴. The company voluntarily recalled this parenteral-nutrition product about two months later and warned patients and the health care practitioner to dispose of their supplies to avoid the serious consequences.  Hence, it would be always beneficial to stabilize more and more drug products irrespective of their physicochemical peculiarities at room temperature from their prescribed storage condition which require refrigeration or subzero temperature storage for maintaining the desired quality of the drug throughout the shelf life of the product. 

The Posaconazole injection is such drug product wherein the recommended storage of the drug product is 2 - 8°C. This work will focus on stabilizing the drug product at room temperature by one or more the techniques discussed subsequently in this work.  The storage temperature of the drug product is decided based on the extent of impurities generated at the stability conditions as specified by the ICH guideline Q1A (R2) “Stability Testing of New Drug Substances and Products.⁵

The RLD formulation Noxafil is available in the market which is in solution form and is stable at Refrigerator condition i.e. 2 to 8 °C. The refrigerated condition is difficult to maintain at manufacturing location, transportation and at the site of end user i.e patient or the small dispensaries in the remote areas^6-9. This may sometimes lead to inadvertent exposure of the drug product to a higher temperature leading to degradation of the drug product thus jeopardising the efficacy of the formulation.

The aim of the present work is to stabilize the formulation at room temperature which otherwise is stable at 2-8°C or refrigerated storage condition, to achieve the same different permutation and combination of drug and the excipient were tried to develop the formulation of desired efficacy and stability.

MATERIAL AND METHODS

Posaconazole was procured from Dr. Reddy’s Laboratory. Betadex sulfobutyl ether sodium (SBECD), edetate disodium, propylene glycol, dimethyl acetamide, ethanol, sodium metabisulfite (SMBS), sodium ascorbate, sodium ascorbate, polysorbate 80, arginine, L-Cysteine, hydrochloric acid, sodium hydroxide were obtained from Loba Chemie PVT. LTD.. All other reagents used in the study were of analytical grade

Formulation of posaconazole solution

About 10 formulation trials of posaconazole solution were designed based on solubility profile of posaconazole drug and its compatibility with the excipients as shown in table 1. The water for injection (80 %), purged nitrogen to achieve the dissolved oxygen content of 2 ppm or less. Continued nitrogen purging throughout the batch manufacturing. The pH of the water for injection was checked. A sodium ascorbate and sodium metabisulfite was added slowly under continuous stirring. The stirring was continued till get clear solution. This was followed by addition of propylene glycol, and ethanol with stirring. The pH was adjusted to 2.6. The posaconazole was then added slowly under stirring for 2 h and was observed for complete solubility of the API in the selected solvent system.

Table 1: Formulation trials of posaconazole solution

Lyophilization 

The prepared solution was filled in a glass vials, the vials were half stoppered and were loaded on the precooled shelf in the lyophilizer. During the secondary drying the cycle time at step 40°C was 1000 minutes. The total duration of cycle was 66 hours.²

Evaluation of lyophilized powder and or Cake

The lyophilized powder or cake was evaluated for physical appearance, moisture content and reconstitution time 

Physical appearance

The physical appearance i.e description and color of the lyophilized powder was determined.

Moisture Content 

Moisture content was determined using Karlfisher titration. The cake was weighed approximately 400 mg and was added to the KF titrator ^3. 

Reconstitution time

The Vial having lyophilized powder was taken and removed flip off seal. The 17 mL of water for injection was taken in 20 ml disposable syringe and injected in to the vial. Then the vial was shaken till the lyophilized powder and or cake was completely dissolved. The time at which the solution becomes clear colourless solution recorded. 

RESULT AND DISCUSSION

Development of the Lyophilization Cycle

Lyophilization cycle depends upon the number of parameters viz.  freezing point, critical temperature and vapor pressure of the formulation. To optimize all these 13 trials were done and results are summarized in table no.2. 

Fixing of Freezing Stage

The shelves of the lyophilizer were pre-cooled to 5°C before loading the vials into the lyophilizer; this was done in order to minimize the rate of degradation due higher temperature. As discussed above, the freezing temperature was finalized as -45°C since the drug formulation was aqueous based. The ramp rate selected was neither too high e.g. 1°C per minute or neither too slow of 0.1°C per minute, but optimum ramp rate of 0.35°C per minutes was chosen for freezing step. The complete freezing was ensured by providing sufficient time for freezing.

Development of Primary Drying

After freezing the product to -45°C, the product was slowly heated to -30°C at the ramp rate of 0.35°C per minute. Since conservative approach was adopted for the initial development of lyophilization cycle, the temperature of -30°C (critical temperature -25°C) was selected as the primary drying temperature which was in-line with the literature references which indicates that the primary drying temperature shall be lower than the critical temperature ^10-12. After carrying out the drying for 20 hours (1200 minutes) at -30°C, the product was slowly ramped to 20°C at rate of 0.11°C per minute to -20°C at this temperature product was hold for 10 hours (600 minutes) after completing the hold, the product was ramped to 10°C slightly at a higher rate of 0.6°C per minute, at the temperature of 10°C the product was held for 16.67 hours before proceeding for secondary drying. During the entire primary drying at all the temperature condition vacuum of 100 mtorr was maintained.

Secondary Drying

After completion of the primary drying stage the product was heated to 40°C at the slow ramp rate of 0.3°C per minute, at this temperature the product was held for 33.33 hours at the vacuum of 50 mtorr to ensure complete drying. After completion of the lyophilization cycle the lyophilizer was back filed partially with nitrogen and the vials were stoppered and unloaded from the lyophilizer. The cycle of the trial was illustrated in the table 2.

Table 2: Lyophilization cycle of the Trial 1

The vials were observed for physical appearance, reconstitution time and moisture content and the results were given in the table 3.

Table 3: Results of evaluation of lyophilized powder and or cake

Table 4: Lyophilization cycle of the Trial 2

 The vials were observed for physical appearance, reconstitution time and moisture content and the results are given in table 5. 

Table 5: Results of evaluation of lyophilized powder and or cake

Table 6: Results of evaluation of lyophilized powder and or cake (Trial 3)

Table 7: Results of evaluation of lyophilized powder and or cake (Trial 4)

In the further trials from 6 to 13 the focus will remain on the temperature optimization and reducing the cycle time. The freezing step was kept same as the previous trial; The following changes were done in the primary drying stage:

1. The step of -10°C was removed (which was there in Trial 6).
2. After completion of freezingstep the temperature was raised to -5°C from -45°C slowly at the ramp rate of 0.235°C per minute.
3. The overall duration of primary drying was decreased from 51.72 hours to 40.33 hours.
4. The overall cycle time was reduced from 101 hours to 89 hours 

After completion of the lyophilization cycle, the vials were stoppered, unloaded from the lyophilizer and sealed. The observation of the lyophilized vials is given in table 8. 

Table 8: Results of evaluation of lyophilized powder and or cake (Trial 5)

In this trial (Trial 7) the primary drying temperature was further increased to 0°C from -5°C  and to +20°C from +10°C respectively, as compared to the previous trial 7. The primary drying duration was kept unchanged. The vials were stoppered unloaded and sealed. The observation of the sealed vials is given in table 9.

Table 9: Results of evaluation of lyophilized powder and or cake (Trial 6)

Table 10: Results of evaluation of lyophilized powder and or cake (Trial 7)

In the trial 8 all the parameters were kept constant and the hold time during the primary drying (20°C) and secondary drying (40°C) was reduced by 400 minutes and 500 minutes respectively. The total cycle time was reduced by 900 minutes i.e. 11 hours when compared with the trial 9. After completion of the lyophilization cycle, the vials were stoppered, unloaded, sealed. The drug product was evaluated for parameters given in table 11. 

Table 11: Results of evaluation of lyophilized powder and or cake (Trial 8)

Following success of this trial one more trial (Trial 9) was planned in which the temperature at the primary drying stage was increased to +10°C from the 0°C, during the cycle slight melt back was observed through the watch glass hence, the cycle was aborted in between.

The Lyophilization cycle in trial 9 is given in table 12.

Table 12: Lyophilization cycle of the Trial 9

Since, the above trial (Trial 9) resulted in melt back when the temperature was raised to +10°C from 0°C; another trial (This trial 10) was planned in which primary drying temperature was set at 5°C without any other changes. After completion of the lyophilization cycle(table No. 5.12). The vials were stoppered, unloaded and sealed. The drug product was evaluated for the parameters given in the table No. 5.12.

Table 13: Lyophilization cycle of the Trial 10

Table 14: Results of evaluation of lyophilized powder and or cake

The success of trial 10 gives assurance that the trial 9 can be further optimized with respect to time without causing melt back or any other cake defects. The primary drying temperature of 0°C also have required cushion in trial 9 also have the required  Based on this trial it was decided to further optimize the lyophilization cycle of trial 9. 

The first and second step of primary drying i.e. 0°C and 20°C respectively was finalized in the trial 9. This cycle (Trial 11) and further trials will be executed for optimization of cycle time with the aim to reduce the duration of cycle so as to make the product more cost effective.

In this trial the duration of cycle was reduced during the step by 200 minutes and 300 minutes at step of 20° and 40°C respectively, thereby decreasing the cycle time by 9 hours i.e. from 78 hours to 69 hours.

The observations of the lyophilized vials are given below in Table No. 5.14

Table 15: Lyophilization cycle of the Trial 11

Table 16: Results of evaluation of lyophilized powder and or cake

In this trial during the secondary drying the cycle time at step 40°C was reduced by by 200 minutes i.e. the cycle time was reduced from 1200 minutes to 1000 minutes. The total duration of cycle was reduced by 3 hours as compared to previous trial i.e. from 69 hours to 66 hours. The observations of the lyophilized vials are given below in table  

Table 16: Lyophilization cycle of the Trial 12

Table 17: Results of evaluation of lyophilized powder and or cake

In this trial the cycle time was reduced at the following steps as compared with the previous cycle:

1. 0°C : Cycle time was reduced from 1200 minutes to 1000 minutes.
2. 20°C: Cycle time was reduced from 600 minutes to 400 minutes.
3. 40°C: Cycle time was reduced from 1000 minutes to 800 minutes

The total duration of Lyophilization cycle was reduced by 600 minutes i.e. 10 hours hence, the cycle was reduced from 66 hours as in trial 12 to 56 hours in trial 13. The observations of the lyophilized vials are given below table 18.

Table 18: Results of evaluation of lyophilized powder and or cake

From the above observations it is evident that the further reduction in the cycle time would not be feasible as this would result in increase in moisture content which may lead to degradation of the drug product over stability and other product related issues hence, further stability batches will be manufactured using the Lyophilization cycle.

Stability study

Based on the various trials carried out in order to optimize the lyophilization cycle – The lyophilization cycle of trial 12 was finalized. The same cycle is presented below:

Table 19:  Stability data

Evaluation of lyophilized powder and or cake

The cake obtained after lyophilization were subjected to evaluate for its physical appearance, moisture content and reconstitution time. The cake is white, free flowing granular dry powder moisture content of cake was ranges in between. The cake was completely dissolved in few    min.  Same type of results were obtained in previously published literature¹³. Based on the physical test results it was depicted that the lyophilized product was within the acceptance criteria. 

CONCLUSION

The results obtained in this study demonstrated the drug product stability upto 12 months at real time stability condition and 6 months at accelerated stability condition. Hence, it can be inferred that by adding suitable excipients and by subjecting the drug product to lyophilization has helped to stabilize the drug product at room temperature which was originally stable at refrigerated condition.

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