Timolol Concentrations Research Articles

Novel quantum dots-based assay for the determination of anti-hypertensive drugs minoxidil and timolol in different matrices

The present work reports a sensitive, affordable, and ecologically friendly spectrofluorimetric method for the assessment of two antihypertensive medications, namely minoxidil and timolol. Blue-emitting sulfur and nitrogen co-doped carbon quantum dots (S,N-CQDs) were generated by exposing soluble starch and thiourea to a 15-minute microwave treatment. The so- prepared nanodots displayed fluorescence at 276/430 nm with a quantum yield of 22 %. Inspection of the so-prepared nano-sensor verified their doping with nitrogen and sulfur, and their size was in the range of 4.5–9.03 nm. The proposed method was found to be rectilinear in the range of 0.20–5.0 and 2.0–30.0 µg/mL, with LOQs of 0.16 and 0.82 µg/mL for minoxidil and timolol, respectively. The developed method was employed to assess the concentrations of minoxidil and timolol in their pharmaceutical formulations, with %recoveries varying between 99.00 % and 101.94 %, and low RSD values (less than 2 %). The high sensitivity of the developed method allowed its use for timolol measurement in artificial aqueous humor, with % recoveries between 97.60 %.and 101.57 %. The study further examined how each analyte interacted with the prepared dots, leading to a quenching of their fluorescence. Additionally, an interference study was utilized to evaluate the specificity of the proposed approach through determining analyte levels in the existence of common additives, co-formulated drugs, and co-administered drugs. The analytical eco-scale, GAPI and AGREE assessment techniques were utilized to confirm the suggested method greenness.

Patient Factors Influencing Intraocular Penetration of Brimonidine-Related Eye Drops in Adults: A Post Hoc Pooled Analysis.

The factors related to the ocular penetration of drugs after the administration of eye drops in humans have not been examined in detail. Therefore, this study assessed the influence of patient factors on the intraocular penetration of eye drops. A pooled analysis was performed on the data of 42 participants from three studies to evaluate the ocular pharmacokinetics in humans after the topical application of brimonidine-related eye drops. The patients were scheduled for vitrectomy and received brimonidine-related eye drops (0.1% brimonidine tartrate ophthalmic solution, 0.1% brimonidine tartrate and 0.5% timolol fixed-combination ophthalmic solution, or 0.1% brimonidine tartrate and 1% brinzolamide fixed-combination suspension) twice daily for 1 week. We analyzed the effects of patient factors (sex, the presence or absence of lens, age, corneal thickness, corneal endothelial cell density, tear secretion, eye axial length, height, weight and body mass index [BMI]) on brimonidine, timolol and brinzolamide concentrations in the aqueous and vitreous humor after topical application. The drug concentrations in the aqueous and vitreous humor were not significantly different, regardless of sex or the presence or absence of lens. Age correlated positively with brimonidine (r = 0.3948, p = 0.012) and brinzolamide (r = 0.6809, p = 0.030) concentrations in the aqueous humor; the correlation with timolol showed a trend towards significance (r = 0.6425, p = 0.086). Corneal thickness, corneal endothelial cell density, tear secretion, eye axial length, height and BMI did not correlate with the drug concentrations in the aqueous or vitreous humor. Timolol concentration in the vitreous humor was negatively correlated with weight (r = - 0.8333, p = 0.010). The findings of this study emphasize the necessity of considering individual differences in ocular pharmacokinetics during drug therapy (formulation design of the eye drops and dose regimen).

A randomized clinical trial comparing three fixed combinations of bimatoprost with timolol in patients with open-angle glaucoma or ocular hypertension

Objective: To compare the efficacy and safety of two fixed combination, preservative-free eye drops (bimatoprost 0.01% in combination with either timolol 0.1% or 0.5%) in a gel formulation, with bimatoprost 0.03%/timolol 0.5% in patients with open-angle glaucoma (OAG) or ocular hypertension (OHT). Methods: Phase II, randomized, investigator-masked, multicenter, 3-arm parallel group (Eudract No. 2017-002823-46). Eighty-six patients aged ≥18 years with OAG or OHT, with intraocular pressure (IOP) initially controlled for at least 6 months by a combination therapy of a dual prostaglandin and timolol or insufficiently controlled by first-line monotherapy were included. Patients were randomized to receive T4030a (bimatoprost 0.01%/timolol 0.1%; N = 29), T4030c (bimatoprost 0.01%/timolol 0.5%; N = 29) or bimatoprost 0.03%/timolol 0.5% (N = 28), administered once daily in the evening for 12 weeks. Primary endpoint was defined as change in IOP from day 1 to week 12 measured at 08:00 (±1 hour). Further efficacy, safety and pharmacokinetic endpoints were assessed as secondary outcomes. Results: The mean change in IOP from baseline to week 12 was -9.8 ± 2.1 mmHg for T4030a, ­10.1 ± 2.5 mmHg for T4030c and -10.0 ± 2.8 mmHg for bimatoprost 0.03%/timolol 0.5%. All treatments were well tolerated with no safety issues identified in any group. In patients treated with T4030a, the systemic concentration of timolol was significantly lower after 12 weeks than in patients treated with T4030c or bimatoprost 0.03%/timolol0.5%. Conclusions: These study results suggest that the preservative-free ophthalmic formulation of T4030a (bimatoprost 0.01%/timolol 0.1%) can be regarded as a useful tool in the therapeutic management of OAG and OHT.

Numerical simulation and analysis of the temporal concentration of timolol after topical administration in the human eye

The temporal distribution of drugs in the eye tissues after the topical dosing is required to study the efficacy of the drugs. Glaucoma is one of the primary causes of vision impairment around the world and timolol is used in the treatment of glaucoma in general. This paper contributes to developing a model to represent the more accurate biophysics of the human eye through the finite element method compared to other state-of-the-art simulation models. A 2D human-eye model is used to simulate the temporal distribution of timolol after topical dosing within the COMSOL Multiphysics environment. The biophysics of the human eye including temperature regulation, fluid flow in the anterior segment, convection, diffusion, reaction kinetics of timolol, and metabolic consumption are incorporated in the proposed simulation model. The temporal concentration of timolol is analyzed for seven ocular tissues (cornea, iris, sclera, aqueous humor, lens, ciliary body, and trabecular meshwork) in this work. The peak concentration of timolol takes place within 2500 s in the ocular tissues considered in the simulation and the peak in the anterior chamber is observed at 1150 s. The comparison based on the normalized concentration of timolol in the anterior chamber demonstrates that the results of the proposed ocular model comply close with the practical findings. The mean difference with the experimental results is lower in this study compared to the recent numerical works on timolol. The proposed model can be used for analyzing the physiological behavior of human eyes under different types of drug delivery with varying initial concentrations.

Analysis of topical dosing and administration effects on ocular drug delivery in a human eyeball model using computational fluid dynamics

Predicting the spatial and temporal drug concentration distributions in the eyes is essential for quantitative analysis of the therapeutic effect and overdose issue via different topical administration strategies. To address such needs, an experimentally validated computational fluid dynamics (CFD) based virtual human eye model with physiologically realistic multiple ophthalmic compartments was developed to study the effect of administration frequency and interval on drug concentration distributions. Timolol was selected as the topical dosing drug for the numerical investigation of how administration strategy can influence drug transport and concentration distribution over time in the human eye. Administration frequencies employed in this study are 1–4 times per day, and the administration time intervals are Δt = 900 s, 1800 s, and 3600 s. Numerical results indicate that the administration frequency can significantly affect the temporal timolol concentration distributions in the ophthalmic compartments. More administrations per day can prolong the mediations at relatively high levels in all compartments. CFD simulation results also show that shorter administration intervals can help the medication maintain a relatively higher concentration during the initial hours. Longer administration intervals can provide a more stable medication concentration during the entire dosing time. Furthermore, numerical parametric analysis in this study indicates that the elimination rate in the aqueous humor plays a dominant role in affecting the drug concentrations in multiple ophthalmic compartments. However, it still needs additional clinical data to identify how much drugs can be transported into the cardiac and/or respiratory systems via blood circulation for side effect assessment.

Sustained Delivery of Timolol Using Nanostructured Lipid Carriers-Laden Soft Contact Lenses.

The contact lens prepared by the conventional soaking method using timolol-soaking solution showed poor drug uptake and high burst release with altered critical lens properties. In this study, timolol-loaded nanostructured lipid carriers (NLCs) were prepared and evaluated for enhanced timolol uptake and sustained release for the effective management of glaucoma. The characterization studies indicated that timolol-loaded NLCs were spherical in shape with an average size of 130-138 nm and a zeta potential of -46.6 to 51.3 mV. Critical lens properties such as swelling, optical transmittance, and protein adherence were improved with NLC-laden lenses compared to the conventional soaked lenses (SM-TB). Moreover, SM-TB lens showed low timolol uptake, high burst release, and short release duration up to 24 h compared to timolol-NLC-laden lens that showed high timolol uptake, and the cumulative release was sustained up to 96 h. The ability to sustain timolol release improved proportionally with an increase in the amount of Capmul MCMC8 (liquid lipid) in NLCs. In addition, NLC-laden lens was found to be safe according to the results of ocular irritation and histopathological studies. In the rabbit tear fluid model, NLC-30%-Cap-CL batch showed high timolol concentration at all time points up to 60 h. Further, pharmacodynamic study showed sustained reduction in IOP by NLC-30%-Cap-CL batch for 96 h compared to 48 h and 6 h with SM-TB lens and eye drop solution, respectively. In conclusion, NLCs enhanced timolol uptake in the contact lens from the soaking solution using soaking method with improved in vitro and in vivo results for better clinical outcomes in the patients with glaucoma.

Combination product of dermal matrix, human mesenchymal stem cells, and timolol promotes diabetic wound healing in mice

Diabetic foot ulcers are a major health care concern with limited effective therapies. Mesenchymal stem cell (MSC)-based therapies are promising treatment options due to their beneficial effects of immunomodulation, angiogenesis, and other paracrine effects. We investigated whether a bioengineered scaffold device containing hypoxia-preconditioned, allogeneic human MSCs combined with the beta-adrenergic antagonist timolol could improve impaired wound healing in diabetic mice. Different iterations were tested to optimize the primary wound outcome, which was percent of wound epithelialization. MSC preconditioned in 1 μM timolol at 1% oxygen (hypoxia) seeded at a density of 2.5 × 105 cells/cm2 on Integra Matrix Wound Scaffold (MSC/T/H/S) applied to wounds and combined with daily topical timolol applications at 2.9 mM resulted in optimal wound epithelialization 65.6% (24.9% ± 13.0% with MSC/T/H/S vs 41.2% ± 20.1%, in control). Systemic absorption of timolol was below the HPLC limit of quantification, suggesting that with the 7-day treatment, accumulative steady-state timolol concentration is minimal. In the early inflammation stage of healing, the MSC/T/H/S treatment increased CCL2 expression, lowered the pro-inflammatory cytokines IL-1B and IL6 levels, decreased neutrophils by 44.8%, and shifted the macrophage ratio of M2/M1 to 1.9 in the wound, demonstrating an anti-inflammatory benefit. Importantly, expression of the endothelial marker CD31 was increased by 2.5-fold with this treatment. Overall, the combination device successfully improved wound healing and reduced the wound inflammatory response in the diabetic mouse model, suggesting that it could be translated to a therapy for patients with diabetic chronic wounds.

Fractional 2940-nm Er:YAG laser-assisted drug delivery of timolol maleate for the treatment of deep infantile hemangioma

Objective To study the efficacy and safety of fractional 2940 nm laser-assisted drug delivery of timolol maleate 0.5% solution for the treatment of deep IHs. Methods In this study, 30 deep IHs were included, and a fractional 2940 nm laser was applied with 2-weeks intervals. Topical timolol maleate 0.5% was applied under occlusion for 30 min four times/day for 24 weeks. The plasma concentration of timolol maleate was monitored for 0.5 h after the first treatment. The HAS scores and the depth, lateral diameter, vertical diameter of hemangiomas were evaluated before treatment, at 8 weeks and 24 weeks of treatment, and at 4 weeks after treatment. Results Twenty-three patients (76.7%) demonstrated excellent regression, 4(13.3%) showed good response, and 3(10%) experienced moderate regression. The HAS score was declined from 3.6 ± 0.7 to 2.3 ± 0.6 at 8 weeks, and from 1.3 ± 0.5 to 0.8 ± 0.5 at 24 weeks (p < .05). Plasma timolol concentration was not detected in 11 infants, and the rest ranged from 1.580 pg/mL to 14.718 pg/mL, which were <1 ng/mL. No systemic complications were observed in any patients. Conclusion Fractional 2940 nm laser-assisted drug delivery of timolol maleate 0.5% is considered to be an effective and safe method for treating deep IHs.

Ocular and Systemic Pharmacokinetics of Brimonidine and Timolol After Topical Administration in Rabbits: Comparison Between Fixed-Combination and Single Drugs.

IntroductionThis study was aimed to compare ocular tissue distribution and systemic exposure of brimonidine and timolol after single topical administration to rabbits of fixed-combination ophthalmic solution of 0.1% brimonidine tartrate and 0.5% timolol and single drugs (0.1% brimonidine tartrate ophthalmic solution or 0.5% timolol ophthalmic solution) or concomitant administration of single drugs.MethodsRabbits were treated with a single topical administration of each ophthalmic solution or concomitant administration of single drugs. For concomitant administration, 0.1% brimonidine tartrate was administered after 0.5% timolol instillation successively within 10 s (without interval) or with 5-min intervals. Brimonidine and timolol concentrations in the aqueous humor, retina/choroid, vitreous body, and plasma were determined with liquid chromatography-tandem mass spectrometry.ResultsThe area under the curve values of both drugs in the aqueous humor after fixed-combination administration were comparable to those after concomitant administration. The value of brimonidine was comparable to that after 0.1% brimonidine tartrate administration, whereas the value of timolol was 1.6-fold higher than that after 0.5% timolol administration. The plasma area under the curve value of brimonidine did not differ between fixed-combination and single-drug administrations, but that of timolol was higher after fixed-combination administration than after single-drug administration. Similar concentration-time curves of brimonidine were observed in the posterior ocular tissues in all groups. For concomitant administration, both drug concentrations in the aqueous humor without an administration interval were lower than those with 5-min intervals.ConclusionThere was no difference in the effect of formulation compositions on ocular and systemic pharmacokinetics among the ophthalmic solutions, but brimonidine may alter the ocular and systemic absorption of timolol, which is possibly due to its pharmacologic action. We demonstrated the importance of an administration interval in the concomitant administration of these drugs. This concern could be avoided by using a fixed combination of brimonidine and timolol.

New technique to reduce systemic side effects of timolol eye drops: The tissue press method-Cross-over clinical trial.

Nasolacrimal occlusion (NLO) is effective in reducing systemic absorption of eye drop medication but it is difficult and often performed poorly. We propose an alternative easier and equally effective technique. To test the effectiveness of systemic absorption, we evaluated plasma concentration and ocular effects after topically administered timolol and compared to NLO. Cross-over trial carried out in Capital Eye Specialist, Wellington. A total of 21 subjects over 18 years without contraindications for topical beta-blocker medication and not using systemic beta-blockers. During three clinic visits separated by at least one week, alternative approaches to reduce systemic eye drop absorption were tested. These were: (a) nasolacrimal (punctal) occlusion for 5 min, (b) tissue press method or (c) no intervention. Timolol plasma levels were measured 1 h after drop application. At each visit, baseline measurement of blood pressure, heart rate and intraocular pressure (IOP) were performed, and repeated 1 h after timolol 0.5% eye drop application. Comparison of timolol plasma concentration after each intervention. Secondary outcome measurements included effects on blood pressure, heart rate and IOP. Plasma timolol concentrations after tissue press method and NLO were significantly lower than those without intervention. Comparing tissue press method to NLO, there were no significant differences in plasma levels of timolol, blood pressure, heart rate or IOP. The tissue press method is equally effective as NLO in reducing systemic absorption of timolol. It is also easier and faster to administer.

Absorption and Safety of Topically Applied Timolol for Treatment of Chronic Cutaneous Wounds.

Objective: There are no safety or absorption studies to guide topical timolol therapy for treatment of chronic wounds. This study was undertaken to address this gap. Approach: A prospective, observational, cross-sectional comparative study of timolol plasma levels in patients after topical administration to a chronic wound, compared with levels in patients after timolol ocular administration for the indication of glaucoma. Results: There was no statistically significant difference in the average plasma level of timolol in wound as compared with glaucoma patients. No bradycardia or wheezing was observed after administration. Innovation: We determined the single time point concentration of timolol in plasma 1 h after application of timolol 0.5% gel-forming solution to debrided chronic wounds, providing insight as to the safety of this emerging off-label treatment. Conclusion: The topical application of timolol for chronic wounds shares the same safety profile as the widely used application of ocular administration for glaucoma.

Chemotherapy-induced isolated right pan-retinal atrophy

INTRODUCTIONTopically applied ocular medications could be sufficiently absorbed to inflict untoward systemic consequences.1-4 Timolol, a non-selective beta blocker is capable of eliciting severe asthmatic attacks in susceptible individuals. Timolol absorption is via nasal mucosa to systemic circulation. On another hand, systemically administered medications could through ophthalmic and ciliary arteries reach ocular tissues to unleash lethal effects. For instance chloroquine and its derivative, hydroxychloroquine sulphate, which have been useful in treating malaria and in larger doses, collagen-vascular disease, cause a cumulative dose-related pigmentary retinopathy.5,6 Mechanisms of action include inhibition of critical enzymes and interference with the metabolic functions of Retinal Pigment Epithelium (RPE) and photoreceptors. Both drugs apparently have a selective affinity for melanin, so they get concentrated in RPE and uveal tissue and are retained for long periods, even after their usage is stopped.

936 Systemic absorption and safety of topical timolol for chronic wounds

936 Systemic absorption and safety of topical timolol for chronic wounds

Effect of gold nanoparticles on timolol uptake and its release kinetics from contact lenses: In vitro and in vivo evaluation

Contact lenses are ideally suited for extended drug delivery to the ocular tissues, but incorporation of any particulate system affects the critical properties of the contact lens. Timolol loading by the conventional soaking method does not significantly alter the critical properties of the contact lens. However, there are challenges of low drug loading and high burst release. This research work aimed to investigate the effect of gold nanoparticles (GNPs) on loading and its release kinetics from the contact lens using the soaking method. In one approach, GNPs were loaded into the timolol soaking solution (GNPs-SS), and in another approach, GNPs were incorporated into the contact lenses (GNPs-CL) during fabrication. The contact lenses were soaked at two different concentrations of timolol (i.e., 2 mg/ml and 4 mg/ml). Swelling and optical transmittance were not significantly affected by the presence of GNPs in the contact lenses. A significant uptake/loading of timolol using the GNPs in both the approaches was observed. The in vitro flux data showed no significant improvement in the release rate profiles of timolol when using both approaches. However, the in vivo study in the rabbit tear fluid showed high timolol concentration with the GNPs-laden contact lens at all timepoints in comparison to the soaked contact lenses without GNPs. The in vivo pharmacodynamic study in rabbits showed a 2 mmHg average fall in intraocular pressure (72 h) using the GNPs-laden contact lenses, while the soaked contact lenses without GNPs and eye drops solution (0.5 %w/v) showed 2 mmHg. The drug distribution study in the ocular tissue showed a significant improvement in the drug deposition with the GNPs-laden contact lenses in the ciliary muscle and conjunctiva. This study successfully demonstrated the potential of GNPs to enhance the uptake of drug from the drug soaking solution to treat glaucoma without compromising the critical properties of contact lens. Statement of SignificanceIn this study, we have overcome the limitation of the conventional soaking method of low drug loading and high burst release from the contact lenses. We have investigated the effect of gold nanoparticles (GNPs) on the timolol loading and its release kinetics from the contact lenses. The study revealed the potential of GNPs to enhance the uptake of timolol from the timolol soaking solution to treat glaucoma without compromising the critical lens properties.

Effect of dosing regimen and microneedle pretreatment on in vitro skin retention of topically applied beta-blockers.

Topical beta-blocker formulations are commonly used to treat infantile hemangiomas (IHs); however, the skin concentrations and drug permeation through the skin have not been quantified. Microneedles (MNs) may increase local skin concentrations, which could further enhance lesion clearance and improve dosing regimens. The objective of this study was to quantify skin concentrations and drug permeation of two beta-blockers, propranolol and timolol, in vitro after application to intact skin and skin pretreated with solid MNs of two lengths. Propranolol skin concentrations and drug permeation were significantly higher than timolol skin concentrations for all study conditions, which is likely due to the lipophilic nature of propranolol compared to the hydrophilicity of timolol. Propranolol skin concentrations were significantly influenced by dosing regimen, as skin concentrations increased with increasing drug application. Pretreatment of the skin with solid 250μm and 500μm length MNs increased local skin concentrations of timolol; propranolol skin concentrations did not significantly increase after MN pretreatment. Propranolol and timolol permeation through the skin increased after MN pretreatment with both MN lengths for both compounds. Taken together, solid MN pretreatment prior to application of topical timolol may be beneficial for deep or mixed IHs upon further optimization of the MN treatment paradigm.

A Novel Method to Eliminate Preservatives in Eye Drops.

Multiuse eye drops must maintain sterility and typically accomplish this by added preservatives. However, preservatives often cause harmful side effects. A gauze barrier dressing ("BIOGUARD®") recently cleared by the FDA has an immobilized poly diallyldimethylammonium chloride (p-DADMAC) coating and is an effective antimicrobial with minimal compound release into solution. To implement use of this dressing as a replacement for preservatives in multidose eye drop bottles, its ability to maintain sterility without interacting with the active ingredient (AI) of the ophthalmic medication was tested. To determine immobilized p-DADMAC's microbicidal efficacy, it was added to eye drop bottles, then contaminated with Staphylococcus aureus (SA113) bacteria. To assess interference with AI in eye drops, high performance liquid chromatography was used to determine whether the AIs timolol and dorzolamide were affected after exposure to p-DADMAC. To further investigate effects on AI, the microbicidal activity of Vigamox® (moxifoxacin) was assessed after p-DADMAC gauze exposure. S. aureus bacteria were eliminated by p-DADMAC-treated gauze for all samples. The concentrations of both timolol and dorzolamide increased after exposure to p-DADMAC-treated gauze, but spectrometric analysis showed that this did not occur when the p-DADMAC-coated material was presoaked in deionized water. The microbicidial activity of moxifloxacin was unaffected by exposure to p-DADMAC-treated gauze. Due to its lack of effect on eye drop AI and its microbicidal efficacy, p-DADMAC treatment would make an excellent candidate for replacing preservatives in eye drops.

Development of a novel ion-pairing UPLC method with cation-exchange solid-phase extraction for determination of free timolol in human plasma

A novel UPLC-UV method was developed for analysis of timolol in human plasma using a simple, fast, and cost effective ion-exchange SPE procedure, followed by separation on a C18 UPLC column with a mobile phase consisting of acetonitrile, phosphate buffer, and sodium 1-octane sulfonate as an ion pairing agent. The method was fully validated according to US-FDA guidelines, and was found to be sufficiently accurate and precise for analysis of timolol in human plasma for clinical pharmacokinetic studies. The application of ion-exchange SPE cartridges for purification of timolol in plasma produced excellent percent recoveries and good sample clean-up, while the ion-pairing separation described here allowed quantitation of timolol without interference from endogenous sample components. The method lower limit of detection was 1.7 ng/mL and the lower limit of quantitation was 5.0 ng/mL, allowing for analysis of therapeutic concentrations of timolol in plasma.

Influence of Pilocarpine and Timolol on Human Meibomian Gland Epithelial Cells.

Investigators have discovered that topical antiglaucoma drugs may induce meibomian gland dysfunction. This response may contribute to the dry eye disease commonly found in patients with glaucoma taking such medications. We hypothesize that drug action involves a direct effect on human meibomian gland epithelial cells (HMGECs). To test this hypothesis, we examined the influence of the antiglaucoma drugs, pilocarpine and timolol, on the morphology, survival, proliferation, and differentiation of HMGECs. Immortalized (I) HMGECs (n = 2-3 wells/treatment/experiment) were cultured with multiple concentrations of pilocarpine or timolol for up to 7 days. Experiments included positive controls for proliferation (epidermal growth factor and bovine pituitary extract) and differentiation (azithromycin). Cells were enumerated using a hemocytometer and evaluated for morphology, neutral lipid staining, and lysosome accumulation. Our results demonstrate that pilocarpine and timolol cause a dose-dependent decrease in the survival of IHMGECs. The clinically used concentrations are toxic and lead to cell atrophy, poor adherence, or death. By contrast, drug levels that are known to accumulate within the conjunctiva, adjacent to the meibomian glands, do not influence IHMGEC survival. These latter concentrations also have no effect on IHMGEC proliferation or differentiation, and they do not interfere with the ability of azithromycin to stimulate cellular neutral lipid and lysosome accumulation. This dose of pilocarpine, though, did suppress the epidermal growth factor+bovine pituitary extract-induced proliferation of IHMGECs. Our results support our hypothesis and demonstrate that these antiglaucoma drugs, pilocarpine and timolol, have direct effects on HMGECs that may influence their morphology, survival, and proliferative capacity.

Colorimetric determination of Timolol concentration based on localized surface plasmon resonance of silver nanoparticles

In this work, a rapid and simple colorimetric method based on the surface plasmon resonance of silver nanoparticles (AgNPs) was developed for the detection of the drug Timolol. The method used is based on the interaction of Timolol with the surface of the as−synthesized AgNPs, which promotes aggregation of the nanoparticles. This aggregation exploits the surface plasmon resonance through the electric dipole–dipole interaction and coupling among the agglomerated particles, hence bringing forth distinctive changes in the spectra as well as the color of colloidal silver. UV−vis spectrophotometery was used to monitor the changes of the localized surface plasmon resonance of AgNPs at wavelengths of 400 and 550 nm. The developed colorimetric sensor has a wide dynamic range of 1.0 × 10−7 M–1.0 × 10−3 M for detection of Timolol with a low detection limit of 1.2 × 10−6 M. The proposed method was successfully applied for the determination of Timolol concentration in ophthalmic eye−drop solution with a response time lower than 40 s.

Advantages of Efficacy and Safety of Fixed-Dose Tafluprost/Timolol Combination Over Fixed-Dose Latanoprost/Timolol Combination.

PurposeTo compare the safety and efficacy of fixed-dose tafluprost/timolol combination (Taf/T-FDC) with those of fixed-dose latanoprost/timolol combination (Lat/T-FDC) by measuring the intraocular pressure (IOP)-lowering effect, ocular pharmacokinetics, and ocular surface toxicity.MethodsThe IOP-lowering effect of Taf/T-FDC and Lat/T-FDC in ocular normotensive monkeys was evaluated at 4 and 8 h after instillation in study A, at 12, 14, 16, and 18 h after instillation in study B, and at 24, 26, 28, and 30 h after instillation in study C. Drug penetration into the eye was evaluated by measuring the concentrations of timolol, tafluprost acid (active metabolic form of tafluprost), and latanoprost acid (active metabolic form of latanoprost) using liquid chromatography coupled with tandem mass spectrometry after single instillation of Taf/T-FDC or Lat/T-FDC to Sprague Dawley rats. Cytotoxicity following 1–30 min exposure of SV40-transformed human corneal epithelial cells to Taf/T-FDC or Lat/T-FDC was analyzed using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assays. Undiluted and 10-fold diluted solutions of each FDC were evaluated.ResultsThe IOP-lowering effect of Taf/T-FDC was almost equivalent to that of Lat/T-FDC at 4–8 h after instillation. The peak IOP reduction of Taf/T-FDC and Lat/T-FDC was observed at 8 h after instillation, and there is no difference between the two. The difference between them was observed at 24–30 h after instillation, and Taf/T-FDC demonstrated a significantly greater IOP-lowering effect than Lat/T-FDC at 24–30 h after instillation. The IOP-lowering effect of Taf/T-FDC was sustained up to 30 h after instillation, while that of Lat/T-FDC had almost disappeared at 28 h after instillation. Timolol concentrations in aqueous humor after Taf/T-FDC instillation were higher than those after Lat/T-FDC instillation (Cmax, 3870 ng/mL vs 1330 ng/mL; AUCinf, 3970 ng·h/mL vs 1250 ng·h/mL). The concentrations of tafluprost acid and latanoprost acid in aqueous humor after instillation of Taf/T-FDC and Lat/T-FDC, respectively, were similar to those after instillation of mono-preparations of tafluprost and latanoprost, respectively. The cytotoxic effect of Taf/T-FDC to the human corneal epithelial cells was significantly lower than that of Lat/T-FDC at all evaluated time points in both undiluted and 10-fold diluted FDCs.ConclusionTaf/T-FDC provides increased IOP-lowering effect duration and lower potential ocular surface toxicity than Lat/T-FDC.