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Cross-Linked Polymers for Drug Delivery Systems
Published in Munmaya K. Mishra, Applications of Encapsulation and Controlled Release, 2019
Galgatte et al. prepared mucoadhesive in situ gel formulations for prolonged residence time and enhanced drug uptake [56]. The gels were loaded with sumatriptan succinate, a drug used for the treatment of cluster headaches and migraine, which is limited by low oral bioavailability resulting from hepatic metabolism. Its transportation across the blood–brain barrier is also poor. To overcome the aforementioned limitations associated with the drug, it was loaded onto in situ gels prepared from deacetylated gellan gum. The in vitro drug release from the formulation was 98.6% within 5 h, and the ex vivo drug release on sheep nasal mucosa was 93% within 5 h. An in vivo study on Sprague-Dawley (SD) rats revealed an absolute bioavailability of 165%, and the drug targeting index for brain tissues was 1.87. The drug release from the formulation was influenced by the viscosity of the formulation. The drug targeting index suggested that sumatriptan reached the brain via the olfactory pathway. The in situ gel enhanced the permeation of drug molecules across the nasal mucosa through olfactory pathways [56]. Jagdale et al. loaded timolol maleate, a drug used to treat hypertension, onto in situ gels prepared from HPMC and Poloxamer 407 [57]. The drug suffers from extensive hepatic first-pass metabolism with a half-life of 4 h. The highest percentage drug release from both the optimized formulations via egg membrane was 81% and 84%. The drug release was influenced by the viscosity of the in situ gel. Ex vivo drug diffusion via nasal mucosa was 61% and 67% for both formulations. The gelation temperature for the formulations was in the range of 31–36°C, and it decreased with increasing concentration of Poloxamer 407 and HPMC in the formulations. Intranasal administration of the drug via in situ gel has the potential to improve the drug bioavailability and lower the dosing frequency [57]. Wang et al. loaded geniposide onto in situ mucoadhesive, thermoreversible gel to increase the residence time of the drug in the nasal cavity [58].
Timolol loaded microemulsion laden silicone contact lens to manage glaucoma: in vitro and in vivo studies
Published in Journal of Dispersion Science and Technology, 2021
Ning Wei, Hui Dang, Chao Huang, Yanjuan Sheng
New Zealand rabbits (male and female) were used to investigate the release profiles of timolol in the tear fluid from selected TB-SM-3 (234.3 ± 18.5 μg) and TB-ME-SM-2 (215.3 ± 9.1 μg) contact lenses in comparison to a 0.5% w/v timolol eye drop solution (Lopres, MICROVISION) (1 drop ≈ 50 µl ≈ 250 µg timolol maleate). The sterile timolol-contact lens was placed on the left eye (n = 6) of rabbits (right eye was kept control) without local anesthesia. In the eye drop group, the rabbit’s left eye received single drop of timolol eye drop (right eye was kept control). The rabbit tear fluid was collected using disposable glass capillary from the cul de sac and preserved at -20 °C until analysis. The timolol-tear fluid samples were treated with 1 ml of methanol to precipitate proteins, followed by freeze and centrifugation (Remi freeze-centrifuge) for 1 h at 5000 RPM. The collected supernatant was analyzed for timolol by HPLC method.
Synthesis and evaluation of modified lens using plasma treatment containing timolol-maleate loaded lauric acid-decorated chitosan-alginate nanoparticles for glaucoma
Published in Journal of Biomaterials Science, Polymer Edition, 2023
Maryam Sadat Hosseini, Mojdeh Mohseni, Masood Naseripour, Mehdi Mirzaei, Kowsar Bagherzadeh, Sayyed Amirpooya Alemezadeh, Bita Mehravi
Ocular hypertension associated with an increase in intraocular pressure (IOP) is the reason for glaucoma [5]. Pharmacological and surgical treatments try to prevent the progression of the disease and new damage by reducing IOP [6]. Timolol-maleate (TM) is a beta-adrenergic receptor antagonist as an effective drug treatment for glaucoma [7]. Although 90% of the drugs are in the form of eye drops, these formulations are very weak in penetrating with a high rate of elimination. The increment of systemic absorption of TM, and side effects in the central nervous, respiratory, and cardiovascular systems, limit this drug’s clinical applications [8, 9].
Therapeutic contact lenses for ophthalmic drug delivery: major challenges
Published in Journal of Biomaterials Science, Polymer Edition, 2020
Xiuju Zhang, Xiuzhen Cao, Ping Qi
Lipophilic vitamin E was used as a barrier to retard the release of ocular drugs. Vitamin E possess antioxidant and UV blocking properties, it slow down the progress of age-related macular degeneration, and inhibit keratocyte apoptosis [49]. The unprocessed contact lens is soaked in the vitamin E ethanol solution, were the contact lens matrix swell to form a big pores in the contact lens to partition vitamin E. The swollen lens is removed after 24 h from the vitamin E concentrated ethanol solution and washed with the saline solution to shrink in the pre-deformed shape trapping vitamin E in the matrix of the lens [50–52]. Chauhan and his coworkers demonstrated the use of vitamin E as a physical barrier to create extended wear contact lens without affecting the optical transparency. Other molecules like timolol, fluconazole, and dexamethasone were tested with vitamin E, which showed prolong release up to factor 400 with 0.4 g vitamin E/g of hydrogel [53]. Integration of vitamin E sustained the release of latanoprost for 10 days with > 50% bioavailability in comparison to the eye drops [54]. The anti-bacterial efficacy of ofloxacin- vitamin E loaded contact lens was promising against Staphylococcus aureus and Pseudomonas aeruginosa in an ex vivo rabbit corneal model [55]. The release of ketorolac tromethamine and flurbiprofen sodium was sustained using vitamin E and surfactants [56]. The Beagle dog studies demonstrated the efficacy of vitamin E laden timolol and dorzolamide lens to be as potent eye drop solutions. The contact lenses with 20% vitamin E increase the release rate duration from 2 h to 24 h with 5 mmHg reduction in the IOP. The dual drug delivery is possible using such system. However, the critical issues like increase in the size (30% vitamin E loading in the lens cause 6.5% increase in lens size), decrease in ion-permeability (10% loading shows 50% reduction), increase in protein adherence and decrease in oxygen diffusion (75% loading shows 40% reduction) [53] need to be addressed. Commercial manufacturing point of view, the system needs additional step of vitamin E incorporation in the lens, followed by drug loading and sterilization. The uncontrolled release of drug with time in the packaging solution is not the major issue, as the method is based on equilibrium drug loading mechanism. The ongoing safety evaluations in the human trails attracted the commercial implementation.