scholarly journals Layered double hydroxide/sepiolite hybrid nanoarchitectures for the controlled release of herbicides

2019 ◽  
Vol 10 ◽  
pp. 1679-1690 ◽  
Author(s):  
Ediana Paula Rebitski ◽  
Margarita Darder ◽  
Pilar Aranda
Keyword(s):  
Controlled Release ◽  
Ion Exchange ◽  
Single Step ◽  
Basal Spacing ◽  
In Vitro Tests ◽  
Bidistilled Water ◽  
Continuous Release ◽  
Agricultural Applications ◽  
Double Hydroxides

In this work, organic–inorganic hybrid nanoarchitectures were prepared in a single coprecipitation step by assembling magnesium–aluminum layered double hydroxides (MgAl-LDH) and a sepiolite fibrous clay, with the simultaneous encapsulation of the herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) as the MgAl-LDH retains its ion exchange properties. The synthetic procedure was advantageous in comparison to the incorporation of MCPA by ion exchange after the formation of the LDH/sepiolite nanoarchitecture in a previous step, as it was less time consuming and gave rise to a higher loading of MCPA. The resulting MCPA-LDH/sepiolite nanoarchitectures were characterized by various physicochemical techniques (XRD, FTIR and 29Si NMR spectroscopies, CHN analysis and SEM) that revealed interactions of LDH with the sepiolite fibers through the silanol groups present on the outer surface of sepiolite, together with the intercalation of MCPA in the LDH confirmed by the increase in the basal spacing from 0.77 nm for the pristine LDH to 2.32 nm for the prepared materials. The amount of herbicide incorporated in the hybrid nanoarchitectures prepared by the single-step coprecipitation method surpassed the CEC of LDH (ca. 330 mEq/100 g), with values reaching 445 mEq/100 g LDH for certain compositions. This suggests a synergy between the inorganic solids that allows the nanoarchitecture to exhibit better adsorption properties than the separate components. Additionally, in the release assays, the herbicide incorporated in the hybrid nanoarchitectures could be completely released, which confirms its suitability for agricultural applications. In order to achieve a more controlled release of the herbicide and to act for several days on the surface of the soil, the hybrid nanoarchitectures were encapsulated in a biopolymer matrix of alginate/zein and shaped into spheres. In in vitro tests carried out in bidistilled water, a continuous release of MCPA from the bionanocomposite beads was achieved for more than a week, while the non-encapsulated materials released the 100% of MCPA in 48 h. Besides, the encapsulation may allow for better handling and transport of the herbicide.

Bio-Resorbable Nanoceramics for Gene and Drug Delivery

MRS Bulletin ◽  
2004 ◽  
Vol 29 (1) ◽  
pp. 33-37 ◽  
Author(s):  
Waltraud M. Kriven ◽  
Seo-Young Kwak ◽  
Matthew A. Wallig ◽  
Jin-Ho Choy
Keyword(s):  
Drug Delivery ◽  
Controlled Release ◽  
Layered Double Hydroxides ◽  
Negative Charge ◽  
Acidic Environment ◽  
Biological Cells ◽  
Double Hydroxides ◽  
Or Genes

AbstractNanoscale ceramic particles, such as layered double hydroxides (LDHs), have been developed to deliver drugs or genes into biological cells. In this article, we describe the controlled-release properties of LDHs as drug delivery carriers, the formation of bio-LDH nanohybrids, theirin vivoandin vitrocytotoxicity tests, and their potential as anticancer gene delivery carriers. Unstable biomolecules can be intercalated into LDHs, displacing the interlayer anions; the drug or gene's negative charge is thus shielded, enabling penetration into the cell. In the slightly acidic environment of the cell, ceramic nanoplatelets of ∼100 nm diameter dissolve, thus releasing the intercalates in a controlled manner.

scholarly journals Synthesis of Hybrid Organic-Inorganic Hydrotalcite-Like Materials Intercalated with Duplex Herbicides: The Characterization and Simultaneous Release Properties

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 5086
Author(s):  
Sheikh Ahmad Izaddin Sheikh Mohd Ghazali ◽  
Is Fatimah ◽  
Farah Liyana Bohari
Keyword(s):  
Controlled Release ◽  
Basal Spacing ◽  
X Ray Diffraction ◽  
Order Model ◽  
Release Formulation ◽  
X Ray ◽  
Release Property ◽  
Pseudo Second Order ◽  
Dichlorophenoxy Acetic Acid ◽  
Double Hydroxides

In this study, a controlled-release formulation of duplex herbicides, namely, 2,4,5-trichlorophenoxybutyric acid (TBA) and 3,4-dichlorophenoxy-acetic acid (3,4D), was simultaneously embedded into Zn-Al-layered double hydroxides (LDHs). The resulting nanohybrid Zinc-Aluminium-3,4D-TBA (ZADTX) was composed of a well-ordered crystalline layered structure with increasing basal spacing from 8.9 Å to 20.0 Å in the Powder X-ray Diffraction (PXRD) with 3,4D and TBA anions located in the gallery of LDHs with bilayer arrangement. The release of 3,4D and TBA fit the pseudo-second-order model. This duplex nanohybrid possessed a well-controlled release property (53.4% release from TBA and 27.8% release from 3,4D), which was highly effective, requiring the use of a small quantity and, hence, environmentally safer.

Efficacy of controlled-release papaverine pellets in preventing symptomatic cerebral vasospasm

2001 ◽  
Vol 95 (1) ◽  
pp. 44-50 ◽  
Author(s):  
Tayfun Dalbasti ◽  
Murat Karabiyikoglu ◽  
Nurcan Ozdamar ◽  
Nezih Oktar ◽  
Sedat Cagli
Keyword(s):  
Controlled Release ◽  
Sustained Release ◽  
Treated Group ◽  
Local Application ◽  
Control Group ◽  
In Vitro Tests ◽  
Aneurysm Surgery ◽  
Content Type ◽  
Fine Print

Object. Vasospasm as a complication of subarachnoid hemorrhage is a major concern in clinical practice. The systemic drugs in current use are of limited value. Topical, intrathecal, or intraarterial papaverine administered during surgical or angiographic procedures is a potent vasodilating drug; however, hypotension limits its systemic application. Local application of papaverine in a biodegradable controlled- or sustained-release matrix is proposed for vasospasm prophylaxis to be used in patients scheduled for aneurysm surgery. Methods. Controlled-release papaverine (PapaCR) drug pellets were prepared using the biodegradable aliphatic polyester poly(DL-lactide-co-glycolide) as the carrier matrix. In vitro tests were performed to determine drug kinetics. One hundred seventeen patients, 73 assigned to the control group and 44 assigned to the PapaCR-treated group, participated in this study. Patients who were deemed to be at high risk for the development of vasospasm were selected to participate in the study. During aneurysm surgery, drug pellets were placed in cisterns over arterial segments. In two patients, cerebrospinal fluid was sampled every 6 hours for the first 5 days through a lumbar catheter that had been inserted at the beginning of aneurysm surgery. The incidence of clinical vasospasm and Glasgow Outcome Scale scores in the patients were evaluated statistically. The results of in vitro studies showed that effective local concentrations of papaverine could be maintained for more than 10 days. The first-degree drug-release profile was demonstrated using this design. In clinical studies no adverse effects due to the drug were seen. The PapaCR effectively prevented development of clinical vasospasm, and outcome scores were significantly better in patients in the treated group. Conclusions. Local application of controlled- or sustained-release papaverine can be safely used in preventing vasospasm.

Anti-Diabetic Activity of a Mineraloid Isolate, in vitro and in Genetically Diabetic Mice

2011 ◽  
Vol 81 (1) ◽  
pp. 34-42 ◽  
Author(s):  
Joel Deneau ◽  
Taufeeq Ahmed ◽  
Roger Blotsky ◽  
Krzysztof Bojanowski
Keyword(s):  
Dna Microarrays ◽  
Human Fibroblasts ◽  
Diabetic Animal ◽  
In Vitro Tests ◽  
Diabetic Mice ◽  
Fossil Material ◽  
Expression Of Genes ◽  
Enhanced Expression ◽  
Genetically Diabetic Mice

Type II diabetes is a metabolic disease mediated through multiple molecular pathways. Here, we report anti-diabetic effect of a standardized isolate from a fossil material - a mineraloid leonardite - in in vitro tests and in genetically diabetic mice. The mineraloid isolate stimulated mitochondrial metabolism in human fibroblasts and this stimulation correlated with enhanced expression of genes coding for mitochondrial proteins such as ATP synthases and ribosomal protein precursors, as measured by DNA microarrays. In the diabetic animal model, consumption of the Totala isolate resulted in decreased weight gain, blood glucose, and glycated hemoglobin. To our best knowledge, this is the first description ever of a fossil material having anti-diabetic activity in pre-clinical models.

Comparison of High Purity Factor IX Concentrates and a Prothrombin Complex Concentrate in a Canine Model of Thrombogenicity

1991 ◽  
Vol 66 (05) ◽  
pp. 609-613 ◽  
Author(s):  
I R MacGregor ◽  
J M Ferguson ◽  
L F McLaughlin ◽  
T Burnouf ◽  
C V Prowse
Keyword(s):  
High Purity ◽  
Time Course ◽  
Prothrombin Complex Concentrate ◽  
Degradation Products ◽  
Canine Model ◽  
Factor Ix ◽  
In Vitro Tests ◽  
Albumin Infusion

SummaryA non-stasis canine model of thrombogenicity has been used to evaluate batches of high purity factor IX concentrates from 4 manufacturers and a conventional prothrombin complex concentrate (PCC). Platelets, activated partial thromboplastin time (APTT), fibrinogen, fibrin(ogen) degradation products and fibrinopeptide A (FPA) were monitored before and after infusion of concentrate. Changes in FPA were found to be the most sensitive and reproducible indicator of thrombogenicity after infusion of batches of the PCC at doses of between 60 and 180 IU/kg, with a dose related delayed increase in FPA occurring. Total FPA generated after 100-120 IU/kg of 3 batches of PCC over the 3 h time course was 9-12 times that generated after albumin infusion. In contrast the amounts of FPA generated after 200 IU/kg of the 4 high purity factor IX products were in all cases similar to albumin infusion. It was noted that some batches of high purity concentrates had short NAPTTs indicating that current in vitro tests for potential thrombogenicity may be misleading in predicting the effects of these concentrates in vivo.

A Comparison of the in Vitro and in Vivo Thrombogenic Activity of Factor IX Concentrates Using Stasis (Wessler) and Non-Stasis Rabbit Models

1980 ◽  
Vol 44 (02) ◽  
pp. 081-086 ◽  
Author(s):  
C V Prowse ◽  
A E Williams
Keyword(s):  
Platelet Rich Plasma ◽  
Thrombus Formation ◽  
Factor Ix ◽  
Coagulation System ◽  
In Vitro Tests ◽  
Clinical Use ◽  
Low Activity

SummaryThe thrombogenic effects of selected factor IX concentrates were evaluated in two rabbit models; the Wessler stasis model and a novel non-stasis model. Concentrates active in either the NAPTT or TGt50 in vitro tests of potential thrombogenicity, or both, caused thrombus formation in the Wessler technique and activation of the coagulation system in the non-stasis model. A concentrate with low activity in both in vitro tests did not have thrombogenic effects in vivo, at the chosen dose. Results in the non-stasis model suggested that the thrombogenic effects of factor IX concentrates may occur by at least two mechanisms. A concentrate prepared from platelet-rich plasma and a pyrogenic concentrate were also tested and found to have no thrombogenic effect in vivo.These studies justify the use of the NAPTT and TGt50 in vitro tests for the screening of factor IX concentrates prior to clinical use.

In Vitro Thrombogenicity Tests of Factor IX Concentrates

1979 ◽  
Vol 42 (05) ◽  
pp. 1355-1367 ◽  
Author(s):  
C V Prowse ◽  
A Chirnside ◽  
R A Elton
Keyword(s):  
Factor Viii ◽  
Partial Thromboplastin Time ◽  
Generation Time ◽  
Activated Partial Thromboplastin Time ◽  
Factor Ix ◽  
In Vitro Tests ◽  
Factor Viii Inhibitor ◽  
Factor Ixa ◽  
Viii Inhibitor

SummaryVarious factor IX concentrates have been examined in a number of in vitro tests of thrombogenicity. The results suggest that some tests are superfluous as in concentrates with activity in any of these tests activation is revealed by a combination of the non-activated partial thromboplastin time, the thrombin (or Xa) generation time and factor VIII inhibitor bypassing activity tests. Assay of individual coagulant enzymes revealed that most concentrates contained more factor IXa than Xa. However only a small number of concentrates, chiefly those that had been purposefully activated, contained appreciable amounts of either enzyme.

Inhibition of Fibrinolysis and Fibrinogenolysis in Man: Comparison of ε-Aminocaproic Acid and Kallikrein Inhibitor

1963 ◽  
Vol 10 (01) ◽  
pp. 106-119 ◽  
Author(s):  
E Beck ◽  
R Schmutzler ◽  
F Duckert ◽  
Keyword(s):  
Aminocaproic Acid ◽  
Side Reactions ◽  
In Vitro Tests ◽  
Factor V ◽  
Clinical Use ◽  
Strong Inhibitor ◽  
Kallikrein Inhibitor ◽  
Therapeutic Possibilities

SummaryInhibitor of kallikrein and trypsin (KI) extracted from bovine parotis was compared with ε-aminocaproic acid (EACA): both substances inhibit fibrinolysis induced with streptokinase. EACA is a strong inhibitor of fibrinolysis in concentrations higher than 0, 1 mg per ml plasma. The same amount and higher concentrations are not able to inhibit completely the proteolytic-side reactions of fibrinolysis (fibrinogenolysis, diminution of factor V, rise of fibrin-polymerization-inhibitors). KI inhibits well proteolysis of plasma components in concentrations higher than 2,5 units per ml plasma. Much higher amounts of KI are needed to inhibit fibrinolysis as demonstrated by our in vivo and in vitro tests.Combination of the two substances for clinical use is suggested. Therapeutic possibilities are discussed.

Effect of coating method on release of Glimepiride from porosity osmotic pump tablets (POPTs)

2020 ◽  
pp. 37-45
Keyword(s):  
In Vitro Release ◽  
Osmotic Pump ◽  
Release Time ◽  
Once Daily ◽  
Coating Solution ◽  
Continuous Release ◽  
Red Color ◽  
Coating Method ◽  
Osmotic Agent

In this study, once-daily porosity osmotic pump tablets (POPTs) of Glimepiride were prepared using HPMC K100M (61%), osmotic agent (30% NaCl) coated using two different coating techniques spraying and dipping methods. The coating solution composed of ethyl cellulose (7.5%) w\w in ethanol (90%), castor oil (2%) as water-insoluble plasticizer and Gingo red color (0.5% w\w). In both techniques, the coating level was adjusted to give a 10% increase in the weight of the tablets. The effect of the coating by dipping technique with an increase in the weight of tablet (10 %, 20% & 50%) was also investigated to see the effect coating level on the percentage of drug release from POPTs. The results of the in vitro release of Glimepiride from tablets coated by the spraying method showed longer release time (24 hrs) than those coated with dipping method. On the other hand, increasing the coating level by dipping method retarded the release of the drug from tablets. However, the same retardation effect on release as shown with the spraying technique was only obtained by increasing the coating level with a 50% increase in the weight of the tablet. Thus, coating by spraying is more efficient to prepare POPTs to give a continuous release of Glimepiride from once daily table with the lowest increase in the total weight of the tablet.

Controlled Release of Metformin Hydrochloride I. In vitro Release from Physical Mixture Containing Xanthan Gum as Hydrophilic Rate Retarding Polymer

1970 ◽  
Vol 4 (1) ◽  
Author(s):  
Mashkura Ashrafi ◽  
Jakir Ahmed Chowdhury ◽  
Md Selim Reza
Keyword(s):  
Controlled Release ◽  
Xanthan Gum ◽  
In Vitro Release ◽  
Correlation Coefficients ◽  
High Ratio ◽  
Water Soluble ◽  
Metformin Hydrochloride ◽  
Model Drug ◽  
Very High

Capsules of different formulations were prepared by using a hydrophilic polymer, xanthan gum and a filler Ludipress. Metformin hydrochloride, which is an anti-diabetic agent, was used as a model drug here with the aim to formulate sustained release capsules. In the first 6 formulations, metformin hydrochloride and xanthan gum were used in different ratio. Later, Ludipress was added to the formulations in a percentage of 8% to 41%. The total procedure was carried out by physical mixing of the ingredients and filling in capsule shells of size ‘1’. As metformin hydrochloride is a highly water soluble drug, the dissolution test was done in 250 ml distilled water in a thermal shaker (Memmert) with a shaking speed of 50 rpm at 370C &plusmn 0.50C for 6 hours. After the dissolution, the data were treated with different kinetic models. The results found from the graphs and data show that the formulations follow the Higuchian release pattern as they showed correlation coefficients greater than 0.99 and the sustaining effect of the formulations was very high when the xanthan gum was used in a very high ratio with the drug. It was also investigated that the Ludipress extended the sustaining effect of the formulation to some extent. But after a certain period, Ludipress did not show any significant effect as the pores made by the xanthan gum network were already blocked. It is found here that when the metformin hydrochloride and the xanthan gum ratio was 1:1, showed a high percentage of drug release, i.e. 91.80% of drug was released after 6 hours. But With a xanthan gum and metformin hydrochloride ratio of 6:1, a very slow release of the drug was obtained. Only 66.68% of the drug was released after 6 hours. The percent loading in this case was 14%. Again, when Ludipress was used in high ratio, it was found to retard the release rate more prominently. Key words: Metformin Hydrochloride, Xanthan Gum, Controlled release capsule Dhaka Univ. J. Pharm. Sci. Vol.4(1) 2005 The full text is of this article is available at the Dhaka Univ. J. Pharm. Sci. website

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