Dr. Jayachandra Babu Ramapuram is currently a Professor of Pharmaceutics at the Harrison School of Pharmacy, Auburn University, AL. His research interests include 3D printed implants, nanoparticle-based formulations for topical, transdermal, oral delivery, solubility improvement of insoluble drugs, and percutaneous penetration enhancement techniques. He has supervised/supervising 12 graduate students and four postdoctoral fellows in his laboratory. Federal grants and pharmaceutical companies have funded him. He has authored and co-authored 80 peer-reviewed papers, research papers, and ten book chapters and presented his research work in 100 posters/oral presentations in several national and international conferences.
Dr. C. Ramapuram
Aug 4, 2021 Presentation at the Global Conference for Lipid Nanoparticles & Other Non-viral Nanocarriers
Dr. C. Ramapuram: Improvements for Oral Delivery of Pharmaceutical Nanomedicines
T_T Scientific_ Dr. C. Ramapuram_ Improvements for Oral Delivery of Pharmaceutical Nanomedicines
Dr. Nima Tamaddoni
Hey, Dr. Ramapuram, how are you?
Hey, Dr. Nima Tamaddoni. I am doing good. How are you?
Dr. Nima Tamaddoni
Thank you very much. It is great to see you, nice to meet you officially, thank you so much for talking with us. Searching for formulation scientists in this field truly caught my eyes how you differently use the nanoparticles in your applications. So as you know, they are mostly injectable as of now in the market. But there is a lot of room to grow in oral delivery of these Nano medicines and that is truly being lagged. So, I could not wait to see your presentation, thanks for joining us.
Thank you for letting me speaks at the global conference. Thanks for organizing for everyone. And, I hope my topic aligns with your rest of the topics in terms of the content. I thought I will present some information from the work that we have done from our lab in terms of improving the solubility of insoluble drugs for focusing on the overall delivery of some insoluble drug molecules, so…
Dr. Nima Tamaddoni
Exactly! Yeah, that is great, that is the biggest problem with the oral delivery of APIs or as the solubility, when they are hydrophilic or better say hydrophobic, how can you suspend or make it the way that it can be delivered as with the oral way. So, I did not mean to cut you off, I just want to wait to make sure we hit the 3:30 clock, so everybody can take advantage of your presentation.
Great! Can I go ahead?
Dr. Nima Tamaddoni
Oh, yes, absolutely. Yeah, right now 3:30, go ahead. Please.
Alright, good afternoon everybody, good afternoon and good evening for people for representing globally. Thank you to the organizers of this global conference for giving me an opportunity to present some of our research work that is being performed in our lab and I will be focusing on one of the technologies for the solubility improvement of some insoluble drugs for the overall delivery of nanoparticle based formulation. So, we will be focusing, I will briefly talk about a super critical technology approach for improving the solubility of nanoparticles of a model drug molecule. So, a very brief introduction, not to bore you with already known information which has been published and several reviews and books and book chapters, you might have come across this information that this area is very of great importance, very challenging for formulation scientists. There are sixty percent of nuclear entities which are considered fully water soluble and half of the drug molecules which are orally administered, suffer from formulation problems because of high lipophilicity and difficult to formulate in terms of solubilizing them to enable absorption. Especially for class 2 BCS, biopharmaceutical classification system, class 2 compounds.
Those who are not similar to BCS classification system, drugs are broadly classified into four classes, and the class 1 drugs are highly permeable and highly soluble, class 2 drugs are highly permeable but less soluble, in order to make them permeable you need to improve the solubility. So, these are the class of drugs which have got a lot of challenges in terms of formulation for effective delivery across the oral route and other biological membranes as well. So, class three, low permeability high solubility, meaning the formulation has nothing much role to play, and class 4, low permeability low solubility and we will be focusing on class 2 drug molecules in terms of improving their solubility, thereby improve the absorption. So, very brief introduction about looking at this picture here, when you give… Sorry. Okay. So, these are the events as shown in the picture which would occur following oral administration of the solid doses form. Except in case of control release formulations, the disintegration and de-aggregation of the solid dosage forms occur upon ingestion of a tablet or a capsule by oral tract. So, following this the drug must be liberated from this aggregates by the dissolution process, the drug must get into solution, only the solubility drug particles can cross the intestinal membrane barrier and enter into blood circulation.
This means that there is an important prerequisite here that the absorption of a drug by all mechanisms except endocytocytosis is that it must be presented accurate solution. This process in turn depends on drugs accurate solubility and the dissolution rate. Unless the drug goes into solution it cannot be absorbed into systemic circulation focusing on class 2 drugs. So, the table here shows nanoparticle based drug formulations, which are available in the market, which are usually generally prepared by a media milling or ball milling process. Elon technologies, Elon is known for this process for decades and these formulations often use surfactants to aid the milling and de-aggregation of the milling particles. There are many drug molecules here which are solubilized, which are made effective in terms of delivering across the GI-tract. So, there is another table, this table shows the nanoparticle based formulations prepared by high pressure homogenization. Even though these are Nano emulsion formulations meant for topical use and parental use, but there is a high potential for delivering drug molecules by this approach. Nano emulsion approach by oral trout as well. So, let us look at some of the nanoparticle-based systems under development by other technologies other than the top-down of approaches. The nanoparticles are produced broadly by top-down approaches and bottom-up approaches.
Meaning that either you grind the drug particles to Nano size or build up the nanoparticles from the solution state. So, when you look at a bottom up approach or build up approach, so there is a technology commonly used is a super critical fluid based technology. So, there are several techniques under supercritical fluid technologies, supercritical fluid milling and super critical fluid extraction of emulsions and super critical anti-solvent process and solution enhanced dispersion by super critical fluids. All these technologies are used, as one of these technologies is used generally to build the nanoparticles from a solution. So, when you look at some of the advantages of the buildup technologies, build-up technologies have got low energy, it requires low energy for the process, and required simple and less expensive instruments. These are operated at low temperature and suitable for thermal level drugs and narrow particle size distribution and these technologies can be combined with top-down approaches for effective making of the nanoparticles. So, when you look at some of the disadvantages of traditional methods like crystallization. So, crystallization involves temperature induced super saturation and it uses antisolvents and, you know, there are chemical reactions involved in terms of inducing precipitation or crystallization. So, you know, like there are some common issues which are pertinent to visualization or product contamination, large volumes of waste solvents are generated and yield. There is an issue of the yield, there is a lot of drug loss during the crystallization process, and the particle says generally cannot be controlled, they are too large which are non-uniform. So, when you look at other traditional methods for the micronization, generally do crushing, grinding, and milling. But, there are certain problems inherent to the milling approaches or thermal degradation, chemical degradation, product contamination, and more importantly the aggregation problem which is not listed here.
So, common methods to produce a particle formation using super critical fluid technologies, these are the four common methods used which is a rapid expansion of super critical solution, super critical fluid based anti-solvent process, we got a precipitation by compression fluid anti-solvent and a CDS, which is a solution enhance the dispersion of supercritical fluid. So, first of all, let us look at what is meant by a super critical fluid when you talk about supercritical fluid. I will spend a minute to go over this process. So, super critical fluid, this has been illustrated here by means of phase diagram, containing three phases for any given material and so for every substance there is a temperature above which there is it can no longer exist as a liquid, as shown here and similar likewise in the same lines, there is a pressure above which the substance can no longer exist as a gas, no matter how high the temperature is raised. So, these points are called supercritical temperature and super critical pressure and so, they meet at a critical point. So, beyond which the substance has properties, intermediate between liquid and a gas, called a supercritical fluid.
So, in this region the fluid has good solvating power and high diffusivity. So, the solvent properties are beneficial in drug solubilization because the diffusivity of the supercritical fluid and also there are certain properties unique to supercritical fluid or polymer plasticization and extraction of organic solvents or impurities and gas like properties significantly enhance the mass transfer, promote the extraction and reactive selectivity. So, we take advantage of supercritical region in terms of producing nanoparticles in our case. So what are the supercritical fluids, we are talking about, in pharmaceutical use, certain supercritical fluids, like supercritical carbon dioxide is being used. The benefits of supercritical carbon dioxide in terms of its properties are low critical temperature; you are really not talking about increasing the temperature, very high temperature. They are only talking about close to room temperature, 31 degrees for example here and pressure is also somewhat high but not too high. So, low cost and non-flammability and low toxicity environmentally brining properties of carbon dioxide is taken as an advantage here and for pharmaceutical application you use a supercritical carbon dioxide for producing the nanoparticles and also use the extraction of drugs like caffeine from coffee seeds. But, you know, we talk about super critical fluid here in focusing pharmaceutical application. So, which technique, there are many techniques super critical for, which technique to use? If the drug is soluble in carbon dioxide, you follow rapid expansion as a super critical solution technology. If a drug is not soluble in carbon dioxide, then you follow supercritical anti-solvent process or precipitation by compression fluid by anti-solvent or solution enhanced dispersion of supercritical fluid. There are many, you know, you can choose appropriate method based on the solubility of the drug in a particular supercritical fluid.
So, again certain disadvantages of top-down approaches, Micronesia drugs, the main disadvantage we must talk here is the particle of collaboration. Particles Nano-sized drugs have got high surface free energy therefore they are agglomerate. And, so once they agglomerate, the particle size, you know, effective particles decreases and there is a decrease in the solubility and the dissolution rate, not solubility, dissolution rate. So, therefore we have to, we must enhance the, we must keep the Nano size particles de-agglomerated. So, generally how do you de-agglomerate them? Simply by using high shear mixers or tumblers, cannot de-agglomerate them, rotary and vibratory ball mills are not effective and currently there are no effective methods to de-elaborate the particles. So how can we prevent the agglomeration? How can we de-agglomerate the drug particles? So, we follow, in our lab we followed a supercritical anti-solvent drug recipient mixing process, which is a single step process, which has got several advantages. Single step process provides high flow able mixer and potent drugs can be handled and homogeneous drug XP and mixer can be obtained by de-agglomerating the nanoparticles in a single step, that is that benefit.
So, in terms of the process details, so here is the, let us look at the some of the process details before we go. So, the figure here shows the design for the products of nanoparticles for simultaneous co-processing with excipients. As shown here, it consists of carbon dioxide cylinder, and there is a chiller, piston pump for pumping carbon dioxide, there is a heater and high pressure stirred vessel, and high pressure liquid pump here for pumping the drug solution, there is a back pressure regulator. The picture should not appear and the process should not appear too complicated from the picture. Basically, you subject the drug solution to the supercritical fluid in order to produce the nanoparticle. I will explain that. I will try to explain that here briefly. So, the temperature of the vessel is maintained, you know, usually typically for carbon dioxide at around 40 degree Celsius and then the desired amount of excipient such as lactose or microcrystalline cellulose is placed here, typically about one to three grams, it is a lab scale process. Then the material is subjected to desired pressure, like say close to 100 bars. Then the high pressure chamber is stirred at typically around 200 to 300 RPM during the operation and never Epping solution. So, we use the model drug never Epping, the drug solution is made in dichloromethane, highly volatile organic solvent and pumped through the liquid form into the high-pressure vessel and carbon dioxide is pumped as well from the cylinder at a flow rate of 15 gram per minute and in order to prevent the loss of the powder, there is a membrane filter installed, so that the particles are trapped in the high-pressure breadth measure. So, after complete injection of the drug solution, the high pressure vessel is flushed with… after pressurizing and depressurizing the vessel is flushed with several cycles of carbon dioxide to remove the traces of dichloromethane. So, the drug solution from which the particles are built up in the high-pressure belt while the particles are being formed, you have lactose or another excipient like micro-Christine cellulose, one of them is placed here in the vessel, so that the drugs are deposited directly onto the executed particles.
So, there is no scope for the drug particles to get agglomerated. So that is the key step here and key achievement here in this process. Basically, de-agglomerate the particles while they are being formed. So, in terms of characterization, you know, we once we made the nanoparticles, we looked at surface properties by SEM, and we did the solid state characterization by DHC, X-Ray diffraction, and infrared spectroscopy, and then we also looked at the particle size determination and drug loading and dissolution thoroughly tested we have performed. So, when you look at surface properties, so never Epping pure drug has got crystalline properties. Crystal, as shown in the picture here, they got needle shaped crystals, and by SAS process pure neuropin produces particles, nanoparticles but however they are agglomerate and as you can see the particles and high-resolution images, you can see. Even though the particles, nanoparticles are formed, they are agglomerated in the absence of an excipient like lactose or MCC. Therefore, we have introduced the lactose or MCC into the high pressure vessel. Therefore, the particles are deposited directly onto the surface of the excipient as shown in the picture here.
Now, you can see, we got the lactose particles which are phosphorus lacquers at spherical shape and on the surface of the lactose particles, we got the drug particles deposited. Lactose very soluble when you place the particle agglomerate in solution. The lactose dissolves and liberates the nanoparticles in solution. So, after different regulating’s, are ten percent drug loading, and 30 percent drug loading, you see the agglomerates and agglomerates basically on surface of lactose, insoluble drug particles are deposited, so when you place them in solution in a liquid and lactose dissolves and liberate drug particles which will rapidly go into solution. So, we did the same thing for micro crystalline cylinders also. I do not want to go in the interest of time. I want to skip this information because like lactose, natural microcrystalline cellulose also, we got the particle de-agglomeration by depositing onto the surface of MCC. So, when you look at x-ray diffraction analysis of pure drug as well as unprocessed drug as a process drug, they got the similar crystallinity. Crystallinity is not affected; amorphous state is not formed, so therefore there are no physical instability problems by this process and FDI spectrum shows the spectra are super impossible showing that there are no physical chemical interactions of the drug and the excipients, meaning that there are no changes the crystallinity or no conversion to amorphous state. So, there is no chemical interaction between the experience and drugs which is good and DSC again is super impossible in terms of the melting point of new wrapping showing that the directive strength is not altered for neighboring. So, when you look at the dissolution studies for the supercritical fluid-based nanoparticles that are obtained. As you can see naverafin has got four dissolution and SAS process produced neuropin.
As again shows somewhat improved dissolution but the reason for no significant improvement in the dissolution rate for the SAS produced nanoparticles is because they are agglomerate, because it is a highly insoluble drug. The particles tend to agglomerate; we got the similar dissolution profile. However, when we mix with highly soluble material like lactose, we are able to observe somewhat improvement in the dissolution rate. However, when we co-process the lactose and never Epping together in the nanoparticles as you can see, when the particles are, nanoparticles are deposited onto lactose particles as explained before. There is substantial increase in the dissolution rate for neuropathy. So, this is the achievement that we have in our research that we are able to substantially improve the dissolution rate without affecting the crystalline properties of the drug that means that the drug is… the drug excipine mixer is highly stable. So, likewise with the different drug loadings, as you can see the dissolution rate at 10 percent drug loading, 21 percent drug loading, 31 percent drug loading, and beyond 51 percent drug loading, the dissolution rate is for never Epping having substantially higher compared to the physical mixer or SAS drug or the pure commercial drug.
So, similar results were obtained for MCC co-process systems as well and I am not going to talk about MCC, just wanted to give illustration with the lactose itself to enable finish the presentation on time and at different drug loadings of MCC, you can see 13 percent, 37 percent, and then 51 percent of micro crystalline cellulose. The substantial improvement in the dissolution rate for the nanoparticles compared to the physical mixture of nanoparticles with MCC at 1 is to 9 ratio or SAS drug nanoparticles or drug, itself, as you can see compared to the drug, nanoparticles produced by SAS process by co-processing with the excipients, very substantially increasing the dissolution rate. So, in summary, the simultaneous nanoparticle formulation for neuropin has been achieved and while the particles are being de-agglomerated in the presence of either lactose or micro crystalline cellulose, by a process called SASDM process. So, SASDM stands again the super critical anti-solvent technology, process for drug exciting mixing, this is achieved in a particle formation and de-agglomeration are achieved in a single step. So, solid state characterization of the SAS nanoparticles has demonstrated that there are no changes in the crystallinity of the drug and the drug did not undergo any specific chemical interaction with the excipients by the SASDM method that we followed. So, due to formation of a homogeneous drug nanoparticle and excipient mixture, a substantially faster dissolution for the neuropin, which has been achieved by this SAS process? So, the high dissolution rate for neuropin was attributed to efficient de-agglomeration as well as sufficient weighting of the drug particles due to highly soluble excipients, basically which serve as a medium for carrying the nanoparticles in the process. So, with this, I stop my presentation given time allotment by enabling five minutes for answering any questions… I will try to answer your questions. I want to acknowledge my lab group, Satish Chatigari and Ganesh Sang Anwar are the people worked in this project and other fabric people have as assisted. I want to thank my collaborators; Dr. Ram Gupta Professor chemical engineering, and Dr. Oladidon Fassina Professor in bio system engineering at Auburn University. Thank you very much and I hope I can take one or two questions to answer your questions.
Dr. Nima Tamaddoni
Yeah. Thank you so much. It was a great presentation, definitely a different direction of view, for sure. We do have one question, actually two questions from Susan. We have what scale this is being cross produced now?
It is only one gram quantity lab scale quantity, one to three gram quantity, it is lab scale equipment and Dr. Ram Gupta has got a patent on this, and so who is the inventor of this process, and so this is currently, it is a lab scale only.
Dr. Nima Tamaddoni
Okay and two more questions. The first one is for the supercritical preparation method, is it suitable for RNA or peptide encapsulation? And did the temperature and pressure be harmful for the RNA or peptide if you…?
RNA peptide yes, protein no, due to pressure and sometimes may use some organic solvent. Yes RNA and peptides can be handled because the temperature is only 40 degree, room temperature, slightly above room temperature and in terms of this if you follow anti-solvent process, if the drug is soluble, if the peptide is soluble you can follow as explained in the one of the slides here, you can follow the process called… sorry. Just wanted to show the process, which method to follow, the drug, if the peptide RNA is soluble in supercritical carbon dioxide then you can follow rapid expansion of supercritical solution. So, it is very friendly and very gentle in terms of the process, if the drug or RNA, Peptide RNA is not soluble in carbon dioxide, they did not follow other techniques like a supercritical anti-solvent process that means you have to be soluble in a suitable solvent and pump it to the supercritical fluid and the other anti-solvent that used should be volatile, highly volatile solvent like in our case we use a dichloromethane and any anti-solvent can be, sorry, any suitable organic solvent can be used, volatile organic solvent can be used which is an anti-solvent to carbon dioxide, thereby you will be able to produce the nanoparticles. I hope I answered the question and yes it is possible but it requires some research in terms of…
Dr. Nima Tamaddoni
That was great! Good answer and the last question is how scalable is this method and can it be a scale to commercial use in the future?
Yeah. That is the hope. Actually, this technology has been used for extracting the caffeine from the coffee seeds, if that can be done and it can be definitely scalable to larger scale and it is a batch process, of course! And, so this can definitely be scalable to produce kilogram quantities of the nanoparticles in the future.
Dr. Nima Tamaddoni
That is great! That is wonderful. Thank you so much for your time, it was very informational, took a lot of notes and looking forward to seeing you soon again, doctor.
Thank you very much for giving the opportunity to speak in the global conference and I also thank all the audience for their kind attention, appreciate it, thank you.
Dr. Nima Tamaddoni
Of course! Thank you so much.