Nanoparticle-Based Delivery of Plant Metabolites
Megh R. Goyal, Hafiz Ansar Rasul Suleria, Ademola Olabode Ayeleso, T. Jesse Joel, Sujogya Kumar Panda in The Therapeutic Properties of Medicinal Plants, 2019
DDS are therapeutic delivery agents or devices that aid the introduction of a specific substance(s) into the body with enhancement to its effectiveness and safety, by having an effect on the degree, rate, and discharge of the substance in the body. DDSs are known to be delivered via various routes of administration, dependent on the nature of the drug delivery vehicle. Irrespective of the route of administration, the therapeutic agent(s) is/are released from the drug delivery vehicle via two major forms of release systems: Sustained Release Systems: This is a therapeutic release system, which functions as a gradual discharge of the therapeutic agent over a prolonged duration, with the time being sufficient to provide the desirable effect.Controlled Release Systems: This is a therapeutic release system, which manages the conveyance of the drug at a specific rate and for a fixed duration.
Polymer/Surfactant Interaction in Applied Systems
E. Desmond Goddard, James V. Gruber in Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
bridging systems at high flocculant levels and this is due to the adsorption of the polymer onto both the surfaces, resulting in repulsion between the surfaces, rather than bridging. The effect of surfactant concentration may be due to the following. At very low surfactant level, there is excess polymer to adsorb on the particles as well as on the surface, resulting in repulsion between the two. With increase in the surfactant level, the polymer is likely to be partitioned among the surface, the particle, and the micelle, leading to a reduction in the binding to the particle and the surface, and consequently, to a decrease in the repulsion between the particle and the surface. At very high surfactant levels, however, the polymer is predominantly adsorbed on the micelle surface and is not available for bridging. Controlled Release
Selected topics
Henry J. Woodford in Essential Geriatrics, 2022
Lamotrigine's potential adverse effects include rash, insomnia and tremor. Doses have to be slowly titrated upwards at two-week intervals and takes around six weeks to reach the lower end of the therapeutic range. Sodium valproate may cause tremor and weight gain. There is some limited evidence from heterogeneous populations (also used as a mood stabiliser) that it could occasionally cause parkinsonism.49 There have been rare reports of valproate-induced hyperammonaemic encephalopathy.50 Carbamazepine tends to be the least well tolerated AED in older people.47,48 It has a higher risk of drug interactions and hyponatraemia (secondary to SIADH).46 It can also cause a rash. It is usually best avoided in older people.39 When prescribed, controlled release formulations may cause fewer adverse effects.43 Gabapentin is associated with weight gain, tremor and ataxia. Possible adverse effects from levetiracetam include reduced concentration, drowsiness, depression, agitation and irritability.39 Psychosis has also been reported with levetiracetam and topiramate.51 Psychiatric disorders were the commonest adverse event with levetiracetam (26–30% of relatively young people in randomised studies).44,45 AEDs can increase the risk of osteoporosis.
Overcoming challenges for development of amorphous powders for inhalation
Published in Expert Opinion on Drug Delivery, 2020
Rachel Yoon Kyung Chang, Lan Chen, Donghao Chen, Hak-Kim Chan
Hydrophobic excipients may impede the dissolution rate of the amorphous drug which will be detrimental if insufficient drug is released, e.g., for antibiotics where the lung concentration must be above the minimum inhibitory concentration for bacterial killing and minimizing development of drug-resistant strains. Conversely, this trait can potentially be used to an advantage for controlled release to reduce the dose frequency and promote patient compliance. The concept of co-spray drying two drugs (hydrophobic drug with amorphous hydrophilic drug) is popular as it provides added benefit of synergistic activity, such as antimicrobial effect along with moisture protection to the powder by the hydrophobic component. However, this approach should be taken with caution as varying dissolution rates of the two drugs may not necessarily result in synergy.
Preparing of aspirin sustained-release granules by hot-melt granulation and micro-crystal coating
Published in Drug Development and Industrial Pharmacy, 2019
Ran Li, Tian Yin, Yu Zhang, Jingxin Gou, Haibing He, Xing Tang
In this study, two methods for the preparation of aspirin sustained-release granules were proposed, micro-crystal coating and hot-melt granulation. These two methods achieved sustained release by membrane-controlled and matrix-controlled release, respectively. As shown by experiments, granules prepared by hot-melt granulation released completely in 2 h, thus the method was not suitable for making ASP sustained-release granules which meant the matrix-controlled mechanism did not effectively control the release of ASP. For micro-crystal coating, ASP was coated with an isolation layer of PVP, then coated with a sustained-release layer of either Eudragit RL/RS or EC. The release of the two sustained-release granules in vitro was measured in four different dissolution media. The granules coated with an EC released 80% in 24 h, while the granules coated with the Eudragit RS/RL30D released completely in 5 h. This indicated that organic solvent (EC) was more suitable for the preparation of ASP sustained-release granules with micro-crystal coating than the aqueous polymeric dispersion (Eudragit RS/RL30D). The results showed that the micro-crystal coating method was more suitable than hot-melt granulation for the preparation of ASP sustained-release granules, and particularly that micro-crystal coating technology using EC was most suitable for ASP sustained-release granules.
Drug delivery across length scales
Published in Journal of Drug Targeting, 2019
Derfogail Delcassian, Asha K. Patel, Abel B. Cortinas, Robert Langer
In contrast to ingestible devices, transdermal drug delivery methods offer many benefits over the more traditionally administered oral route [37]. First, compared to orally delivered pharmacologics of the same dose, they can provide increased levels of circulating, bioavailable drugs. This leads to a reduction in the drug dose needed to elicit a specific pharmacological effect [38–40], and can, therefore, reduce side effects. Transdermal patches provide a controlled release system which is well suited to the delivery of small molecules, though dermal penetration and delivery efficacy is affected by both the molecular size and hydrophilicity of the therapeutic being administered. Transdermal patches have been widely used to deliver small molecules, such as nicotine in smoking cessation therapies [41] and contraceptive/postmenopausal hormones, such as oestradiol and oestrone [38]. Drug delivery patches are well suited for the continuous, systemic delivery of low dose therapeutics. Drug delivery profiles range from a few days to a few weeks due to limitations in drug loading capacity and patches must remain attached to the skin for the duration of delivery.
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