Amorphous and Crystalline Particulates: Challenges and Perspectives in Drug Delivery

2017 ◽  
Vol 23 (3) ◽  
pp. 350-361 ◽  
Author(s):  
Hisham Al-Obaidi ◽  
Mridul Majumder ◽  
Fiza Bari

Crystalline and amorphous dispersions have been the focus of academic and industrial research due to their potential role in formulating poorly water-soluble drugs. This review looks at the progress made starting with crystalline carriers in the form of eutectics moving towards more complex crystalline mixtures. It also covers using glassy polymers to maintain the drug as amorphous exhibiting higher energy and entropy. However, the amorphous form tends to recrystallize on storage, which limits the benefits of this approach. Specific interactions between the drug and the polymer may retard this spontaneous conversion of the amorphous drug. Some studies have shown that it is possible to maintain the drug in the amorphous form for extended periods of time. For the drug and the polymer to form a stable mixture they have to be miscible on a molecular basis. Another form of solid dispersions is pharmaceutical co-crystals, for which research has focused on understanding the chemistry, crystal engineering and physico-chemical properties. USFDA has issued a guidance in April 2013 suggesting that the co-crystals as a pharmaceutical product may be a reality; but just not yet! While some of the research is still oriented towards application of these carriers, understanding the mechanism by which drug-carrier miscibility occurs is also covered. Within this context is the use of thermodynamic models such as Flory-Huggins model with some examples of studies used to predict miscibility.

Author(s):  
Bhikshapathi D.v.r.n.

Objective The main objective of the present study is systematic development of solid dispersions of Candesartan cilexetil by solvent evaporation method to enhance the solubility and bioavailability. Methods In the present study, eighteen formulations of solid dispersions were prepared with 1:1 and 1:3 ratios of drug: carrier and with and without surfactant. There was significant improvement in the rate of drug release from all 20 solid dispersions and the formulation (SD16) comprising Candesartan: containing Soluplus (1:3 ratio of drug:  Soluplus with 2% SLS as surfactant) by solvent evaporation process. Results Final optimized design SD16 contained maximum drug content of 99.08%. In in vitro dissolution studies it shows greater dissolution rate i.e. 99.7±4.2% associated through additional designs and pure drug. The drug was compatible with all the excipients as per FTIR (Fourier transform infrared spectroscopy). From powder X-ray diffraction (p-XRD) and by (SEM) studies it was evident that crystalline form of Candesartan has been converted into amorphous form within solid dispersion design.  Conclusion From these studies we can accomplish solid dispersions are one of the greatest favorable formulation for Candesartan cilexetil for enhancing the solubility and bioavailability of poorly water soluble drugs in the effective group of hypertension and other cardiac problems.


Author(s):  
Sumant Saini ◽  
Yashwant .

Solid dispersions are one of the most promising strategies to improve the oral bioavailability of poorly water soluble drugs. By reducing drug particle size to the absolute minimum, and hence improving drug wettability, bioavailability may be significantly improved. This article reviews the various preparation techniques for solid dispersion and compiles some of the recent technology transfers. The different types of solid dispersions based on the molecular arrangement have been highlighted. Some of the practical aspects to be considered for the preparation of solid dispersions, such as selection of carrier, solvent and methods of physicochemical characterization, along with an insight into the molecular arrangement of drugs in solid dispersions are also discussed. In this review, it is intended to discuss the recent advances related on the area of solid dispersions.


INDIAN DRUGS ◽  
2013 ◽  
Vol 50 (06) ◽  
pp. 13-19
Author(s):  
R. O Sonawane ◽  
◽  
S. Nayak ◽  
M. D. Chaudhari ◽  
V. V. Pande

The poorly water soluble drugs tend to have low bioavailability and this can be improved by several methods. Solid dispersion is a promising formulation approach to improve solubility and dissolution and ultimately oral bioavailability of these drugs. The aim of this study was to prepare and characterize solid dispersion of anti-diabetic glimepiride, a BCS class II drug, with the hydrophilic carrier PVP K30 by solvent evaporation and microwave induced fusion methods. Scanning electron microscopy (SEM), X–ray powder diffractometry (XRD) and differential scanning calorimetric (DSC) were used to evaluate the physical state of the drug. The solid dispersions were also evaluated for drug content, solubility and dissolution studies. Solid dispersions prepared by solvent evaporation method were showed maximum enhancement of solubility and dissolution in comparison to that prepared by other method.


Author(s):  
RUCHI AGRAWAL ◽  
ABID RAZA ◽  
OM PRAKASH PATEL

Objective: This review article explores solid dispersions (SDs) as one of the suitable approaches to formulate poorly water-soluble drugs. The objective of this review on SD techniques is to explore their utility as a feasible, simple, and economically viable method for augmentation of dissolution of hydrophobic drugs. Methods: Various types of SDs are classified and compared. Use of surfactants to stabilize the SDs and their potential advantages and disadvantages has been discussed. Different techniques for preparing and evaluating SDs are appraised along with discussions on scalability and industrial production. Review of the current research on SD along with future trends is also offered. Results: Based on the various researches, SDs offer an efficient means of improving bioavailability while concurrently contributing to lower toxicity and dose-reduction. Conclusion: Solid-dispersions have been and continue to be one of the key technologies for solving the issue of poor solubility for newer hydrophobic molecules which are being discovered. This would give a new lease of life for such drugs enabling them to be delivered in an effective way.


Author(s):  
Isaiah Ufuoma Efenudu ◽  
Ehi Robert Orhue ◽  
Ogochukwu Jennifer Ikeh ◽  
Michael Aimiesomon Erhayimwen ◽  
Blessing James

The effectiveness of three different extractants soil mixtures—HCl, HCl + H2S04, and DTPA-TEA, in order to determine Si from soil and the forms of Silicon as influenced by different parent materials under acidic medium. Seven forms of Silicon; namely water soluble, specifically adsorbed, oxides bound, organic matter bound, exchangeable, residual, total viz sequential fractionation. Extractable Si value established in this study was (50.0 mg kg-1), indicating negative effect on plant physiology. The physico-chemical properties decreased significantly with increase in soil depth vs soil parent materials. In addition, the forms of Si in the parent materials decreased in the pattern RES, bound residual fractions > EXC, soluble & exchangeable fractions > OM, organic matter fraction. Among the properties the silt fraction, pH & OM significantly and positively correlated with the forms of silicon, with negative correlation vs clay which maybe due to silicon adsorption by clayey fraction of the soil (redox). Therefore the soil maybe be maintained and conserved for farming activities.


Author(s):  
Sanjoy Kumar Das

Improving oral bioavailability of drugs those given as solid dosage forms remains a challenge for the formulation scientists due to solubility problems. The dissolution rate could be the rate-limiting process in the absorption of a drug from a solid dosage form of relatively insoluble drugs. Therefore increase in dissolution of poorly soluble drugs by solid dispersion technique presents a challenge to the formulation scientists. Solid dispersion techniques have attracted considerable interest of improving the dissolution rate of highly lipophilic drugs thereby improving their bioavailability by reducing drug particle size, improving wettability and forming amorphous particles. The term solid dispersion refers to a group of solid products consisting of at least two different components, generally a hydrophilic inert carrier or matrix and a hydrophobic drug. This article reviews historical background of solid dispersion technology, limitations, classification, and various preparation techniques with its advantages and disadvantages. This review also discusses the recent advances in the field of solid dispersion technology. Based on the existing results and authors’ reflection, this review give rise to reasoning and suggested choices of carrier or matrix and solid dispersion procedure.


Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 281
Author(s):  
Nikhila Miriyala ◽  
Daniel J. Kirby ◽  
Aude Cumont ◽  
Ruoying Zhang ◽  
Baogui Shi ◽  
...  

Given the great potential of porous carrier-based drug delivery for stabilising the amorphous form of drugs and enhancing dissolution profiles, this work is focussed on the synthesis and application of carbon onion or onion-like carbon (OLC) as a porous carrier for oral amorphous drug delivery, using paracetamol (PA) and ibuprofen (IBU) as model drugs. Annealing of nanodiamonds at 1100 °C produced OLC with a diamond core that exhibited low cytotoxicity on Caco-2 cells. Solution adsorption followed by centrifugation was used for drug loading and results indicated that the initial concentration of drug in the loading solution needs to be kept below 11.5% PA and 20.7% IBU to achieve complete amorphous loading. Also, no chemical interactions between the drug and OLC could be detected, indicating the safety of loading into OLC without changing the chemical nature of the drug. Drug release was complete in the presence of sodium dodecyl sulphate (SDS) and was faster compared to the pure crystalline drug, indicating the potential of OLC as an amorphous drug carrier.


Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1679
Author(s):  
Thao T.D. Tran ◽  
Phuong H.L. Tran

In recent decades, solid dispersions have been demonstrated as an effective approach for improving the bioavailability of poorly water-soluble drugs, as have solid dispersion techniques that include the application of nanotechnology. Many studies have reported on the ability to change drug crystallinity and molecular interactions to enhance the dissolution rate of solid dispersions using hydrophilic carriers. However, numerous studies have indicated that insoluble carriers are also promising excipients in solid dispersions. In this report, an overview of solid dispersion strategies involving insoluble carriers has been provided. In addition to the role of solubility and dissolution enhancement, the perspectives of the use of these polymers in controlled release solid dispersions have been classified and discussed. Moreover, the compatibility between methods and carriers and between drug and carrier is mentioned. In general, this report on solid dispersions using insoluble carriers could provide a specific approach and/or a selection of these polymers for further formulation development and clinical applications.


Pharmaceutics ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 548 ◽  
Author(s):  
Serena Bertoni ◽  
Beatrice Albertini ◽  
Nadia Passerini

Delivery of poorly water soluble active pharmaceutical ingredients (APIs) by semi-crystalline solid dispersions prepared by spray congealing in form of microparticles (MPs) is an emerging method to increase their oral bioavailability. In this study, solid dispersions based on hydrophilic Gelucires® (Gelucire® 50/13 and Gelucire® 48/16 in different ratio) of three BCS class II model compounds (carbamazepine, CBZ, tolbutamide, TBM, and cinnarizine, CIN) having different physicochemical properties (logP, pKa, Tm) were produced by spray congealing process. The obtained MPs were investigated in terms of morphology, particles size, drug content, solid state properties, drug-carrier interactions, solubility, and dissolution performances. The solid-state characterization showed that the properties of the incorporated drug had a profound influence on the structure of the obtained solid dispersion: CBZ recrystallized in a different polymorphic form, TBM crystallinity was significantly reduced as a result of specific interactions with the carrier, while smaller crystals were observed in case of CIN. The in vitro tests suggested that the drug solubility was mainly influenced by carrier composition, while the drug dissolution behavior was affected by the API solid state in the MPs after the spray congealing process. Among the tested APIs, TBM-Gelucire dispersions showed the highest enhancement in drug dissolution as a result of the reduced drug crystallinity.


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