Plasma timolol concentrations of timolol maleate: timolol gel-forming solution (TIMOPTIC-XE) once daily versus timolol maleate ophthalmic solution twice daily

Natural Gums in Drug-Loaded Micro- and Nanogels

Gums are polysaccharide compounds obtained from natural sources, such as plants, algae and bacteria. Because of their excellent biocompatibility and biodegradability, as well as their ability to swell and their sensitivity to degradation by the colon microbiome, they are regarded as interesting potential drug carriers. In order to obtain properties differing from the original compounds, blends with other polymers and chemical modifications are usually applied. Gums and gum-derived compounds can be applied in the form of macroscopic hydrogels or can be formulated into particulate systems that can deliver the drugs via different administration routes. In this review, we present and summarize the most recent studies regarding micro- and nanoparticles obtained with the use of gums extensively investigated in pharmaceutical technology, their derivatives and blends with other polymers. This review focuses on the most important aspects of micro- and nanoparticulate systems formulation and their application as drug carriers, as well as the challenges related to these formulations.

Ophthalmic drug delivery system based on the complex of gellan and ofloxacin

Complex formation between a natural polysaccharide – gellan and an antimicrobial drug – ofloxacin was studied in aqueous solution. Conductimetric and potentiometric titration curves revealed that gellan and ofloxacin forms a water-soluble complex of composition 2:1 mol/mol stabilized by ionic and hydrogen bonds. The formation of the gellan-ofloxacin complex was confirmed by FTIR spectroscopy, dynamic light scattering, zeta-potential and thermogravimetric analysis. The average hydrodynamic size of the complex was found 307±5 nm and its zeta-potential was negative and equal to -15 mV. Thin films of the gellan-ofloxacin complex, gelled in 0.3 wt.% of CaCl2, were used to study the release kinetics of ofloxacin in distilled water and phosphate buffer. The drug release kinetics evaluated by UV-Vis spectroscopy at λmax = 289 nm and calculated by the Ritger-Peppas model correspond to non-Fickian diffusion in distilled water and Case II transport (zero-order kinetics) in phosphate buffer. The cumulative release of ofloxacin from the gellan-ofloxacin films was equal to 96±2% and 36±2% in phosphate buffer and distilled water, respectively. It is expected that the gellan-ofloxacin complex is able to form in situ gel on the surface of the eye and to prolong the drug residence time in the tear fluid.

Medical Management of Infantile Hemangiomas: An Update

Infantile hemangioma (IH) is the most common benign vascular tumor of infancy, affecting about 5% of infants. It has a characteristic growth pattern of early rapid proliferation followed by progressive involution. Although most IH evolve favorably, complications are observed in 10-15% of cases, justifying treatment. For over 10 years now, propranolol has become the first-line therapy for complicated IH, revolutionizing their management and their prognosis. In this article, we review the clinical features, associations, complications/sequelae and therapeutic approaches for IH, focusing on current medical therapy. Indications for treatment and various treatment options, including propranolol and other oral β-blockers, topical timolol, and corticosteroids are presented. Current controversies regarding oral propranolol such as pre-treatment screening, in- vs out-patient initiation of treatment, early and potential long-term side effects and recommended monitoring are discussed.

Nonselective Beta-Blockers for the Efficacious Healing of Ulcerated Infantile Hemangiomas in Unusual Locations of Two Female Infants

Infantile hemangiomas (IHs) are the most common vascular soft-tissue tumors of newborns and early childhood with a prevalence rate of approximately 4%-5% in infancy. Most of the IHs regress spontaneously after initial proliferation. Ulceration is one of the most common complications seen in IHs, which heal poorly without treatment. The prevalence of IHs is three times more in females compared to males. The most common location of IH is head and neck with the least being in extremities Oral propranolol and systemic corticosteroids are used as first-line therapy in the treatment. Topical timolol has been used as an alternative to counteract the long-term side effects of the prior modalities. In this study, we are reporting and presenting case reports of two female infants with ulcerated IH who were treated with oral propranolol and topical timolol, respectively, and comparing the efficacy of one over the other. we observed fast and efficacious healing with oral propranolol when used with proper monitoring, as compared to topical timolol, although the latter is more commonly used as it is safer with fewer potential side effects.

Repurposing Ophthalmologic Timolol for Dermatologic Use: Caveats and Historical Review of Adverse Events

Ophthalmic timolol solution is increasingly being repurposed as a topical therapeutic for a variety of dermatologic diseases, including pyogenic granulomas, infantile hemangiomas, and chronic wounds. There are no published guidelines or protocols for use in these indications in adults, and the dermatologic community may not be familiar with adverse events that have been extensively documented relating to its ophthalmic use. We review the evidence available relating to adverse events to topical timolol use to evaluate its safety in dermatologic applications and to alert clinicians to screening and monitoring that is needed when repurposing this drug for dermatologic use. The majority of serious adverse events associated with ophthalmic timolol were reported in the first 7 years of use, between 1978 and 1985, of which most common were cardiovascular and respiratory events, but also included 32 deaths. The available evidence suggests that ophthalmic timolol safety profiling may have been incomplete prior to widespread use. Recent clinical trials for dermatologic indications have focused on documenting efficacy and have not had rigorous monitoring for potential adverse events. Topical timolol may be safe and effective for the treatment of various dermatologic conditions in patients whose medical histories have been carefully reviewed for evidence of pre-existing cardiac or pulmonary disease and are monitored for potential adverse events. Despite the wide use of timolol in ophthalmologic practice, safe dermatologic repurposing requires recognition of the potential for facilitated systemic absorption though the skin and appreciation of its history of adverse events.

[Mechanisms of adrenergic β-antagonist for wounds and its application prospect in diabetic foot ulcers]

Objective

To review the research progress of adrenergic β-antagonists on wounds and diabetic chronic cutaneous ulcers healing in recent years, and to investigate its application prospect in diabetic foot ulcer (DFU).

Methods

The latest literature about the role of adrenergic β-antagonists in wounds and diabetic chronic cutaneous ulcers healing was extensively reviewed, and the mechanisms of adrenergic β-antagonists for wounds and its potential benefit for DFU were analyzed thoroughly.

Results

The adrenergic β-antagonists can accelerate the wound healing. The possible mechanisms include accelerating re-epithelialization, promoting angiogenesis, improving neuropathy, and regulating inflammation and growth factors, etc. At present clinical research data showed that the adrenergic β-antagonists may be an adjuvant treatment for diabetic chronic cutaneous ulcers.

Conclusion

Adrenergic β-antagonists maybe promote the healing of wounds and diabetic chronic cutaneous ulcers. However, more long-term follow-up and high-quality randomized control studies are needed to further verify their efficacy and safety for DFU.

Balancing treatments for patients with systemic hypertension and glaucoma

INTRODUCTION

Treatment of glaucoma and systemic hypertension requires careful balancing of ophthalmic and systemic medications. This report offers background on various common therapies and considerations to minimize undesirable systemic and ophthalmic outcomes.

AREAS COVERED

Key considerations relating to medical treatments for systemic hypertension and glaucoma chosen from a review of the literature are included. The historic safety of ophthalmic beta blockers and sub-types as well as combination agents are described. The potential role of ocular perfusion pressure in the pathogenesis of glaucoma is reviewed with a discussion of landmark studies, including the Barbados Eye Study and the Early Manifest Glaucoma Trial, with implications for medication choices for hypertension and glaucoma. Systemic antihypertensives are considered with regards to their potential association with glaucoma and its progression, especially in patients with low blood pressure and normal tension glaucoma. Opinions are offered with regard to therapeutic choices and considerations.

EXPERT OPINION

The medical treatment of systemic hypertension and glaucoma carries the potential for drug interactions and significant adverse effects requiring customization for each patient's particular issues. The evolution of new therapies and treatment paradigms, including laser as a first-line treatment, has expanded safe options and minimized potential dangers for high-risk patients.

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.

Promising Approach in the Treatment of Glaucoma Using Nanotechnology and Nanomedicine-Based Systems

Glaucoma is considered a leading cause of blindness with the human eye being one of the body's most delicate organs. Ocular diseases encompass diverse diseases affecting the anterior and posterior ocular sections, respectively. The human eye's peculiar and exclusive anatomy and physiology continue to pose a significant obstacle to researchers and pharmacologists in the provision of efficient drug delivery. Though several traditional invasive and noninvasive eye therapies exist, including implants, eye drops, and injections, there are still significant complications that arise which may either be their low bioavailability or the grave ocular adverse effects experienced thereafter. On the other hand, new nanoscience technology and nanotechnology serve as a novel approach in ocular disease treatment. In order to interact specifically with ocular tissues and overcome ocular challenges, numerous active molecules have been modified to react with nanocarriers. In the general population of glaucoma patients, disease growth and advancement cannot be contained by decreasing intraocular pressure (IOP), hence a spiking in future research for novel drug delivery systems and target therapeutics. This review focuses on nanotechnology and its therapeutic and diagnostic prospects in ophthalmology, specifically glaucoma. Nanotechnology and nanomedicine history, the human eye anatomy, research frontiers in nanomedicine and nanotechnology, its imaging modal quality, diagnostic and surgical approach, and its possible application in glaucoma will all be further explored below. Particular focus will be on the efficiency and safety of this new therapy and its advances.

Doing the math: A simple approach to topical timolol dosing for infantile hemangiomas

Topical timolol maleate has recently gained popularity as a treatment for superficial infantile hemangiomas, but calculating a safe dose of timolol can be time consuming, which may limit the medication's use in fast-paced clinical environments. This report offers a simplified calculation of the maximum daily safe dosage as 1 drop of medication per kilogram of body weight.

Ophthalmic Timolol Hallucinations: A Case Series and Review of the Literature

PURPOSE

Systemic absorption and central nervous system (CNS) penetration of timolol drops are a well-studied phenomenon, resulting in common side effects such as bradycardia, bronchospasm, fatigue, and confusion. More serious CNS side effects, such as psychosis and depression, however, are rarely attributed to eye drops. We report a case series in which patients developed visual hallucinations secondary to topical ocular timolol use.

METHODS

This study is a case series and review of the literature.

RESULTS

Four patients with glaucoma developed visual hallucinations while using topical timolol. The patients were all elderly, caucasian females with associated CNS pathology. All patients had resolution of symptoms upon discontinuation and a positive retrial test to confirm the association.

CONCLUSIONS

The rarity of this side effect and its anecdotal predilection for elderly, caucasian females with underlying neurological dysfunction, may involve a yet unknown predisposition or hypersensitivity to beta blocker action, such as blood brain barrier disruption leading to increased susceptibility to the medication. This case series highlights an important, although rare, side effect of this medication which clinicians should be aware of especially when using it in elderly patients who may have coexisting CNS pathology. It is important that this side effect be recognized and appropriately managed to prevent otherwise unnecessary investigations and treatment.

Topical Timolol Maleate Treatment of Infantile Hemangiomas

BACKGROUND

There has been a dramatic increase in the off-label use of ophthalmic timolol maleate, a β-blocker used for infantile hemangioma (IH) treatment as a topical counterpart to oral propranolol. Its safety and efficacy in a pediatric population with IH have not been evaluated in a large cohort. Our goal was to retrospectively assess timolol's effectiveness, discern characteristics associated with response, and document reported adverse events.

METHODS

A multicenter retrospective cohort study of 731 patients treated with topical timolol was completed at 9 centers. Inclusion required an IH suitable for timolol in the treating physician's judgment and access to clinical details including photographs. Logistic regression analysis and descriptive statistics were performed. Primary outcome measures were efficacy assessed by using visual analog scales for color and for size, extent, and volume from review of digital photographs taken as standard of care.

RESULTS

Most IHs were localized (80.1%) and superficial (55.3%). Risk of disfigurement was the most common indication for therapy (74.3%). Duration of therapy (P < .0001), initial thinness (P = .008), and subtype (P = .031) were significant predictors of response. Best response occurred in superficial IHs <1 mm thick. Fifty-three (7.3%) required subsequent therapy with systemic β-blocker. Adverse events were mild, occurring in 25 (3.4%) patients. No cardiovascular side effects were documented.

CONCLUSIONS

Timolol seems to be a well-tolerated, safe treatment option with moderate to good effectiveness, demonstrating best response in thin, superficial IHs regardless of pretreatment size. Timolol can be recommended as an alternative to systemic β-blockers and watchful waiting for many patients.

Adverse Events in Young and Preterm Infants Receiving Topical Timolol for Infantile Hemangioma

BACKGROUND

The success of oral propranolol for treatment of infantile hemangiomas (IHs) has led practitioners to use topical β-blockers. In preterm infants, clinicians frequently turn to topical timolol, with the presumption that topical application will result in less systemic absorption. We used Holter monitoring to assess for drug-induced bradycardia in high-risk infants.

METHODS

We retrospectively reviewed the charts of 22 at-risk infants who received a Holter monitor to assess for association between timolol administration and development of significant bradycardia.

RESULTS

Four infants had episodic bradycardia detected by Holter monitoring. Two of these infants were full term; weighed more than 3,000 g; and had rare, brief, asymptomatic episodes unrelated to the timing of the timolol application. The other two infants had symptomatic bradycardia while on timolol and were the only two babies that weighed less than 2,500 g at initiation of therapy. Both were young (postmenstrual age [PMA] 34 and 37 wks) at initiation and had a timolol dose above the average exposure for the cohort.

CONCLUSION

In this cohort of at-risk infants, topical timolol appeared to provide safe treatment for IHs in full-term infants receiving a dose of less than 0.2 mg/kg/day, but infants with a PMA of less than 44 weeks and weight at treatment initiation of less than 2,500 g may be at risk of adverse events, including bradycardia, hypotension, apnea, and hypothermia. We recommend close monitoring of temperature, blood pressure, and heart rate in premature and low-birthweight infants with IHs at initiation of and during therapy with topical timolol.

Efficacious Healing of Ulcerated Infantile Hemangiomas Using Topical Timolol

Infantile hemangiomas (IHs) are the most common benign pediatric soft-tissue tumors. Ulceration—the most frequent complication of IH—tends to heal poorly and is associated with pain, bleeding, infection, and scarring. Mainstay treatment modalities include propranolol (β-blocker) and corticosteroids, whose effectiveness is countered by a need for long-term medication and risk of systemic adverse effects and ulcer recurrence. A 3-month-old infant presented to us with a large, medial thigh-ulcerated IH that progressed despite 2 prior months of dressings and topical antimicrobials. Topical timolol 0.5% thrice daily was initiated, and significant healing was evident at 1 week, with complete healing at 1 month. Timolol was stopped after 3 months, and at 18 months after cessation of timolol, there was no ulcer recurrence. This novel therapy for ulcerated IH seems to have many advantages such as rapid efficacy with easy application, no systemic adverse effects and no long-term recurrence, and current literature describing similar advantages justifies the use of this treatment modality in infants.

RCT of timolol maleate gel for superficial infantile hemangiomas in 5- to 24-week-olds

OBJECTIVE

Timolol maleate 0.5% gel is a safe and effective medication for treating superficial infantile hemangiomas (IHs) in infants with a median age of 9 weeks.

METHODS

Forty-one infants who had superficial IHs without ulceration and not near mucosal surfaces were recruited and randomly assigned to placebo and treatment (timolol maleate 0.5% gel) groups. Efficacy was assessed by performing blinded volume measurements at weeks 0, 1, 2, 3, 4, 8, 12, 16, 20, and 24 and blinded investigator photograph scoring at weeks 0, 12, and 24. Safety was assessed by measuring heart rate and systolic and diastolic blood pressure at weeks 0, 1, 2, 3, 4, 8, 12, 16, 20, and 24.

RESULTS

Fifteen of the 19 infants receiving treatment and 17 of the 22 infants receiving placebo completed the study. Significant color change on the blinded photographic scores was noted at week 24 of the study (P = .003). There was a significantly higher proportion of treated IHs that reduced in size by >5% at weeks 20 and 24 (P < .02). The predicted proportion of IH volume change was also significantly less for treated IHs from week 16 onward when compared with placebo (P < .05). There was no significant variation in blood pressure and heart rate between the groups.

CONCLUSIONS

Topical timolol maleate 0.5% gel with a maximum dose of 0.5 mg per day is a safe and effective option for small superficial IHs that have not ulcerated and are not on mucosal surfaces.

Topical timolol for small hemangiomas of infancy

Propranolol has become the treatment of choice of large and complicated infantile hemangiomas. There is a controversy concerning the safety of systemic propranolol. Here we show that topical use of the beta-blocker timolol can also inhibit the growth and promote regression of infantile hemangiomas. In this case series we treated 11 infantile hemangiomas in nine children including six preterm babies with the nonselective betablocker timolol. A timolol containing gel was manufactured from an ophthalmic formulation of timolol 0.5% eyedrops. This gel was applied using a standardized occlusive dressing (Finn-Chambers) containing approximately 0.25 mg of timolol. In all infants topical timolol was associated with growth arrest, a reduction in redness and thickness within the first 2 weeks. Seven hemangiomas showed almost complete resolution, and four became much paler and thinner. No data are available on the transdermal absorption of timolol. Even supposing complete absorption of timolol from the occlusive dressing, a maximum dose of 0.25 mg of timolol would result per day and hemangioma. Regression of infantile hemangiomas treated using 0.5% timolol gel in this case series occurred earlier than spontaneous regression which is generally not observed before the age of 9-12 months. The promising results need to be verified in prospective randomized trials on topical beta blocker administration for infantile hemangiomas which should address dose, duration, and mode of application.

Topical beta-blocker treatment for migraine

Beta-blockers are a well-known prophylactic treatment for migraine; however, treatment by the ocular route has not been widely considered. This case illustrates the resolution of a visual field defect associated with migraine and improvement of symptoms possibly due to administration of a topical beta-blocker. This novel method of treatment especially when visual field defects are present may have a place in the management of migraine.

Timolol maleate 0.5% or 0.1% gel-forming solution for infantile hemangiomas: a retrospective, multicenter, cohort study

Therapeutic options for superficial infantile hemangiomas (IH) are limited. Recently, timolol maleate gel, a topical nonselective beta-blocker, has been reported as a potentially effective treatment for superficial IH. This study is an extension of a previously published pilot study designed to further investigate the efficacy and safety and to identify predictors of good response of topical 0.5% or 0.1% timolol maleate gel-forming solution. This was a retrospective cohort study including patients enrolled from five centers. Patients were included if they were treated with timolol maleate 0.1% or 0.5% gel-forming solution and had photographic documentation of the IH and at least one follow-up visit. Patients with concomitant active treatment using other IH treatments were excluded. The primary endpoint was change in the appearance of IH as evaluated using a visual analog scale (VAS). Data from 73 subjects were available for final analysis. Timolol maleate gel-forming solution 0.5% was used in 85% (62/73) of patients, the remainder being treated with 0.1%. The median age at treatment initiation was 4.27 months (interquartile range [IQR] 2.63-7.21 mos), and patients were treated for a mean of 3.4 ± 2.7 months. All patients except one improved, with a mean improvement of 45 ± 29.5%. Predictors of better response were superficial type of hemangioma (p = 0.01), 0.5% timolol concentration (p = 0.01), and duration of use longer than 3 months (p = 0.04). Sleeping disturbance was noted in one patient. This study further demonstrates the efficacy and tolerability of topical timolol maleate and gradual improvement with longer treatment in patients with superficial IH.

Ion-activated in situ gelling systems for antisense oligodeoxynucleotide delivery to the ocular surface

Ion-activated in situ gelling systems are able to cross-link with the cations present in the tear fluid, forming a gel on the ocular surface and prolonging corneal contact time. Corneal scrape wounding offers an exceptional model to investigate the efficacy of these formulations for connexin43 (Cx43) antisense oligodeoxynucleotide (AsODN) delivery used to improve wound repair. Systems based on gellan gum and carrageenan have previously been found advantageous in terms of their physicochemical properties, in vitro and in vivo release profiles and precorneal retention. The present study describes AsODN penetration into corneal tissue after wounding and determines the formulations' delivery efficacy by evaluating wound size, tissue inflammation and connexin levels. No difference was shown between the penetration patterns of the formulations, with most of the AsODN accumulating in the epithelium close to the wound leading edge and the stroma underlying the wound. However, significant differences were seen in the delivery efficacy, with gellan gum and carrageenan based systems resulting in the lowest connexin levels and subsequently in the greatest reduction in wound size, the least stromal edema and hypercellularity. This demonstrates their potential use as delivery vehicles for AsODNs to the ocular surface.

Ocular novel drug delivery: impacts of membranes and barriers

BACKGROUND

Ocular drug delivery is an extremely challenging area due to its restrictive barrier functionalities.

OBJECTIVE

Drug transport via corneal/non-corneal routes involves several intricate biological processes such as drug penetration across the ocular barriers and transfer to the anterior or posterior chambers, thus the influence of these processes on the pharmacotherapy of the eye should be fully addressed.

METHODS

To pursue the impacts of such impediments in novel drug therapy, recent publications were reviewed regarding advanced strategies such as nanomedicines.

CONCLUSION

The ocular barriers are highly specialized and selectively control the inward/outward traverse of compounds, hence a better understanding of these biological obstacles would provide a platform to advance ophthalmic drug therapy towards specified delivery/targeting with minimal adverse consequences.

Barriers to glaucoma drug delivery

Topical medications remain the mainstay of glaucoma treatment. This review will aim to cover the pharmacokinetics of topically applied drops, the ocular barriers to drug delivery, and the role of ophthalmic drug formulation in enhancing drug delivery to the target tissue while minimizing side effects and increasing patient compliance. Recent advances in surgical techniques, therapeutic approaches, and material sciences have produced exciting new therapies for ocular diseases. The development of new vehicles and drug formulations that require less patient compliance is also discussed, as are the routes of drug delivery for neuroprotection.

Ophthalmic timolol: plasma concentration and systemic cardiopulmonary effects

Timolol maleate is a non-selective beta-adrenoceptor antagonist currently used mainly as an ocular preparation for the treatment of glaucoma and ocular hypertension. Despite the topical administration, ophthalmic timolol causes systemic adrenergic beta-blocking because of absorption from the eye into the systemic circulation. Gel formulations of ophthalmic timolol have been developed to reduce systemic absorption and adverse effects in comparison with conventional aqueous solution formulations. Timolol is metabolized by the polymorphic cytochrome P450 2D6 enzyme (CYP2D6). The changes in heart rate (HR) are the most striking effects of the systematically absorbed fraction of ophthalmic timolol, with 0.5 % aqueous formulations presenting larger effects than 0.1 % hydrogel formulations, especially during exercise. Plasma levels of ophthalmic timolol correlate with the changes in HR. Neither 0.5 % aqueous nor 0.1 % hydrogel formulations of timolol have exerted noteworthy effects on systolic (SAP) or diastolic (DAP) arterial pressures, probably because of a compensatory increase in systemic vascular resistance due to the attenuation of HR. Ophthalmic timolol does not exert remarkable effects on pulmonary parameter peak expiratory flow (PEF) and forced expiratory volume in 1 s (FEV1) in non-asthmatic patients. CYP2D6 activity is clearly associated with the pharmacokinetic parameters, particularly when 0.5 % aqueous solution of timolol is used: peak plasma concentration, elimination half-life and area-under-the-curve are highest in CYP2D6 poor metabolizers. Finally, since there is a correlation between the plasma level of timolol and several haemodynamic effects - especially HR in the state of elevated beta-adrenergic tonus - the CYP2D6 poor metabolizers may be more prone to bradycardia during treatment with (aqueous) ophthalmic timolol.

Association between low plasma levels of ophthalmic timolol and haemodynamics in glaucoma patients

OBJECTIVES

The aims of the study were to assess the correlation between the plasma concentration of ophthalmic timolol and cardiovascular parameters, and the influence of timolol on advanced haemodynamic variables, such as stroke (SI), cardiac (CI) and systemic vascular resistance (SVRI) indices and arterial pulse wave velocity (PWV).

METHODS

Twenty-five glaucoma or ocular hypertensive patients were treated with 0.5% aqueous and 0.1% hydrogel formulations of timolol using a randomised, double-masked, crossover, multicentre design. All the patients were subjected to passive head-up tilt, electrocardiography, exercise test and measurement of plasma concentration of timolol. In the analysis, the data on the two treatments were combined, and the Spearman correlation coefficients between the plasma level of timolol and physiological effects were calculated.

RESULTS

During the head-up tilt test before rising the bed up, the resting heart rate (HR; R=-0.52, P=0.001) and PWV (R=-0.34, P=0.04) were inversely correlated with timolol level. In the upright position, ophthalmic timolol effectively suppressed the rise in HR (R=-0.36, P=0.03). The SI did not change with timolol concentration, while CI diminished as timolol concentration rose (R=-0.39, P=0.02). The SVRI correlated with timolol concentration (R=0.38, P=0.02). In the exercise test, correlation between HR and plasma level of timolol steadily grew stronger as the load increased, reaching R=-0.60 (P<0.0001) at the maximum load. Systolic and diastolic arterial pressures were not associated with the timolol concentration.

CONCLUSION

The plasma concentration of ophthalmic timolol correlates with several haemodynamic effects. As HR decreases, SVRI increases and blood pressure is kept unchanged.

Topical drug delivery in the eye

Introduction of a drug or polymer directly into the conjunctival sac should, in theory, facilitate the maximum level of efficacy. In practice, most material undergoes non-productive loss. The work of David Maurice facilitated a better understanding of drug entry by the study of probes delivered in several formulations, and by the construction of instruments to study probe distribution. This review describes research on the applications of gamma scintigraphy to follow the residence of polymers in the eye and the evaluation of the data to assess potential new materials. Finally, our progress on the construction of an ocular spectrometer to directly follow drug entry following topical administration is described.