Topical brimonidine 0.2%/timolol 0.5% ophthalmic solution: in glaucoma and ocular hypertension

A fixed combination of brimonidine (a highly selective alpha(2)-adrenergic agonist) and timolol (a non-selective beta-blocker) [brimonidine 0.2%/timolol 0.5% ophthalmic solution; brimonidine/timolol] is available for the topical treatment of glaucoma and ocular hypertension (OH). Brimonidine and timolol decrease elevated intraocular pressure (IOP) by complementary mechanisms of action and have an additive effect when coadministered to healthy volunteers and patients with glaucoma or OH. When assessed over a 3- or 12-month period in large, well designed clinical studies, brimonidine/timolol instilled twice daily (one drop in each eye) was superior to monotherapy with the individual components instilled two (brimonidine) or three (timolol) times daily, and noninferior to concomitant therapy with the individual components instilled twice daily, in lowering raised IOP in patients with glaucoma or OH. In small, randomised, comparative studies of 1 or 3 months' duration, the IOP-lowering effect of brimonidine/timolol twice daily was similar or superior to that of fixed combination dorzolamide 2%/timolol 0.5% ophthalmic solution (dorzolamide/timolol) twice daily (preliminary data). Brimonidine/timolol is generally well tolerated with a predictable local and systemic adverse event profile based on that of the individual components used alone and concomitantly. No unexpected or serious adverse events associated with the fixed combination were reported in key clinical trials. Brimonidine/timolol may be advantageous over dorzolamide/timolol with respect to ocular tolerability and comfort (preliminary data).     

The evolving pharmacotherapeutic profile of brimonidine, an alpha 2-adrenergic agonist, after four years of continuous use

Since its introduction in 1996, use of brimonidine tartrate 0.2% ophthalmic solution (Alphagan, Allergan), a highly selective alpha 2-adrenergic agonist, has become increasingly popular for the initial and long-term management of ocular hypertension and glaucoma. Recently, ongoing clinical comparison trials of up to three years in length have reported sustained intraocular pressure (IOP) lowering efficacy with brimonidine 0.2% b.i.d., which was comparable with timolol 0.5% (Timoptic; Merck & Co.), accompanied by a favourable tolerability and safety profile. Also, many post-market studies have demonstrated the utility of brimonidine 0.2% b.i.d. as mono- and adjunctive therapy. Furthermore, major inroads have been made in the study of other possible pharmacotherapeutic benefits of brimonidine treatment, namely the potential for neuroprotection. This review will present a brief developmental history and examine key pharmacotherapeutic characteristics of brimonidine, including its receptor selectivity, IOP-lowering mechanism of action and potential neuroprotective activities. Moreover, the literature on brimonidine's efficacy and safety profiles in the treatment of ocular hypertension and glaucoma will be perused, and new four-year data from an ongoing double-masked clinical study comparing brimonidine tartrate 0.2% with timolol 0.5%, b.i.d. will be introduced. Brimonidine 0.2% b.i.d. provided sustained IOP-lowering efficacy comparable to timolol 0.5% b.i.d., with no significant differences at trough or peak during year four of continuous use. Visual fields were well preserved in both treatment groups with 93% of brimonidine patients and 91% of timolol patients showing no change or improvement. Brimonidine continued to appear safe and well-tolerated, with no clinically significant effects on mean heart rate or blood pressure, and no serious drug-related adverse events (AEs). Two out of 36 brimonidine patients developed ocular allergy; both were resolved without sequelae. Overall post-market surveillance found no reports of unexpected or serious drug-related AEs. These long-term results, in conjunction with those reported in the literature, suggest that brimonidine 0.2% b.i.d. is a highly appropriate first- and second-line therapy for long-term management of glaucoma and ocular hypertension. Potential neuroprotective effects of brimonidine therapy, which might provide additional vision sparing benefit, although supported by compelling animal studies, await clinical verification.     

The evolving pharmacotherapeutic profile of brimonidine,an 2-adrenergic agonist,after four years of continuous use

Since its introduction in 1996, use of brimonidine tartrate 0.2% ophthalmic solution (Alphagan^®, Allergan), a highly selective ₂-adrenergic agonist, has become increasingly popular for the initial and long-term management of ocular hypertension and glaucoma. Recently, ongoing clinical comparison trials of up to three years in length have reported sustained intraocular pressure (IOP) lowering efficacy with brimonidine 0.2% b.i.d., which was comparable with timolol 0.5% (Timoptic^®; Merck & Co.), accompanied by a favourable tolerability and safety profile. Also, many post-market studies have demonstrated the utility of brimonidine 0.2% b.i.d. as mono- and adjunctive therapy. Furthermore, major inroads have been made in the study of other possible pharmacotherapeutic benefits of brimonidine treatment, namely the potential for neuroprotection. This review will present a brief developmental history and examine key pharmacotherapeutic characteristics of brimonidine, including its receptor selectivity, IOP-lowering mechanism of action and potential neuroprotective activities. Moreover, the literature on brimonidine’s efficacy and safety profiles in the treatment of ocular hypertension and glaucoma will be perused, and new four-year data from an ongoing double-masked clinical study comparing brimonidine tartrate 0.2% with timolol 0.5%, b.i.d will be introduced. Brimonidine 0.2% b.i.d. provided sustained IOP-lowering efficacy comparable to timolol 0.5% b.i.d., with no significant differences at trough or peak during year four of continuous use. Visual fields were well preserved in both treatment groups with 93% of brimonidine patients and 91% of timolol patients showing no change or improvement. Brimonidine continued to appear safe and well-tolerated, with no clinically significant effects on mean heart rate or blood pressure, and no serious drug-related adverse events (AEs). Two out of 36 brimonidine patients developed ocular allergy; both were resolved without sequelae. Overall post-market surveillance found no reports of unexpected or serious drug-related AEs. These long-term results, in conjunction with those reported in the literature, suggest that brimonidine 0.2% b.i.d. is a highly appropriate first- and second-line therapy for long-term management of glaucoma and ocular hypertension. Potential neuroprotective effects of brimonidine therapy, which might provide additional vision sparing benefit, although supported by compelling animal studies, await clinical verification.     

Brimonidine formulation in polyacrylic acid nanoparticles for ophthalmic delivery

In ocular drug delivery, a major problem is providing an adequate concentration of a therapeutic agent in the precorneal area. Mucoadhesive carriers such as polyacrylic acid in sub-colloidal, nanoparticulate form, have a strong potential for ophthalmic drug delivery. A formulation of brimonidine loaded in polyacrylic acid nanoparticles has been prepared for potential delivery in ophthalmic therapy. The particles were prepared by a reverse microemulsion polymerization technique and their sizes were in the range of 50 nm. In a preliminary biocompatibility test, Caco-2 cells (human primary colonic tumour adenocarcinoma) and human corneal epithelial cells incubated with polyacrylic acid nanoparticles were found to retain their viability over varying times. The loading efficiency of the drug brimonidine in the particles was shown to be between 80-85% and pH dependent. The bioadhesive polyacrylic hydrogel nanoparticles, used in the present study, exhibited superior loading properties for brimonidine, and the formulation was stable for more than 5 weeks. When the drug-loaded nanoparticles were dispersed in a phosphate buffer saline (pH = 7.4), the drug was slowly released over several hours. Two-photon laser scanning microscopic studies of dye-conjugated polyacrylic acid nanoparticles demonstrated the accumulation of the particles on the surface and intercellular spaces of Caco-2 cells.     

Brimonidine formulation in polyacrylic acid nanoparticles for ophthalmic delivery

In ocular drug delivery, a major problem is providing an adequate concentration of a therapeutic agent in the precorneal area. Mucoadhesive carriers such as polyacrylic acid in sub-colloidal, nanoparticulate form, have a strong potential for ophthalmic drug delivery. A formulation of brimonidine loaded in polyacrylic acid nanoparticles has been prepared for potential delivery in ophthalmic therapy. The particles were prepared by a reverse microemulsion polymerization technique and their sizes were in the range of 50 nm. In a preliminary biocompatibility test, Caco-2 cells (human primary colonic tumour adenocarcinoma) and human corneal epithelial cells incubated with polyacrylic acid nanoparticles were found to retain their viability over varying times. The loading efficiency of the drug brimonidine in the particles was shown to be between 80–85% and pH dependent. The bioadhesive polyacrylic hydrogel nanoparticles, used in the present study, exhibited superior loading properties for brimonidine, and the formulation was stable for more than 5 weeks. When the drug-loaded nanoparticles were dispersed in a phosphate buffer saline (pH = 7.4), the drug was slowly released over several hours. Two-photon laser scanning microscopic studies of dye-conjugated polyacrylic acid nanoparticles demonstrated the accumulation of the particles on the surface and intercellular spaces of Caco-2 cells.     

Polycarboxylic acid nanoparticles for ophthalmic drug delivery: an ex vivo evaluation with human cornea

In ophthalmic drug delivery, a major problem is retaining an adequate concentration of a therapeutic agent in the pre-corneal area. Polycarboxylic acid carriers such as polyacrylic acid and polyitaconic acid in sub-colloidal, nanoparticulate hydrogel form have a strong potential for sustained release of a drug in ocular delivery. Formulations have been prepared of brimonidine loaded in polycarboxylic (polyacrylic and polyitaconic) acid nanoparticles for potential ophthalmic delivery. These particles were prepared by a reverse micro-emulsion polymerization technique with sizes in the range of 50 nm. The loading efficiencies of the drug brimonidine in the particles were shown to be between 80-85% for polyacrylic acid nanoparticles and between 65-70% for polyitaconic nanoparticles. The loading efficiency was also found to be pH dependent. In a preliminary biocompatibility test, human corneal epithelial cells incubated with polyacrylic acid nanoparticles were found to retain their viability, whereas polyitaconic acid nanoparticles were found to be toxic. Two-photon laser scanning microscopic studies of the fluorescently labelled polyacrylic acid nanoparticles and human cornea shows that they are adhesive on the corneal surface. The polyacrylic acid nanoparticles demonstrated a controlled release of the opthalmological drug (Brimonidine) through the human cornea as compared to that of the commercial formulation, Alphagan.     

Polycarboxylic acid nanoparticles for ophthalmic drug delivery: an ex vivo evaluation with human cornea

In ophthalmic drug delivery, a major problem is retaining an adequate concentration of a therapeutic agent in the pre-corneal area. Polycarboxylic acid carriers such as polyacrylic acid and polyitaconic acid in sub-colloidal, nanoparticulate hydrogel form have a strong potential for sustained release of a drug in ocular delivery. Formulations have been prepared of brimonidine loaded in polycarboxylic (polyacrylic and polyitaconic) acid nanoparticles for potential ophthalmic delivery. These particles were prepared by a reverse micro-emulsion polymerization technique with sizes in the range of 50?nm. The loading efficiencies of the drug brimonidine in the particles were shown to be between 80–85% for polyacrylic acid nanoparticles and between 65–70% for polyitaconic nanoparticles. The loading efficiency was also found to be pH dependent. In a preliminary biocompatibility test, human corneal epithelial cells incubated with polyacrylic acid nanoparticles were found to retain their viability, whereas polyitaconic acid nanoparticles were found to be toxic. Two-photon laser scanning microscopic studies of the fluorescently labelled polyacrylic acid nanoparticles and human cornea shows that they are adhesive on the corneal surface. The polyacrylic acid nanoparticles demonstrated a controlled release of the opthalmological drug (Brimonidine) through the human cornea as compared to that of the commercial formulation, Alphagan?.     

Abuse of Coricidin HBP cough & cold tablets: episodes recorded by a poison center.

Cases involving ingestion of a dextromethorphan-containing product recorded at a poison control center were studied. A retrospective review of all consultations involving the ingestion of Coricidin HBP Cough & Cold tablets recorded by the California Poison Control System was conducted for the period from January 1 to October 1, 2000. Computerized charts on the consultations were reviewed to obtain data on patient age and sex, number of tablets taken, reason for tablet ingestion, symptoms, treatment, disposition, and outcome. A total of 92 charts (for 92 patients) documenting Coricidin HBP Cough & Cold tablet ingestion were reviewed. The reason for tablet ingestion was classified as abuse in 65 patients (71%), a suicide attempt in 8 (9%), misuse in 1 (1%), malicious administration in 1 (1%), and normal use (but with an adverse drug reaction) in 1 (1%); 16 patients (17%) consumed the tablets for an unknown reason. The 92 patients comprised 42 males and 50 females. Among all patients, 78 (85%) were 13-17 years old, and among those classified as having abusive intent, 58 (89%) were in the same age range. The most commonly reported signs and symptoms associated with ingestion were tachycardia (50 patients), hypertension (29), lethargy (40), mydriasis (20), agitation (15), ataxia or dizziness (20), and vomiting (9). Sixty-one patients (66%) had some alteration in mental status. Fifty-six (61%) were treated in the emergency department; 11 (12%) were admitted. All patients recovered completely. Information on the ingestion of Coricidin HBP Cough & Cold tablets recorded at a poison control center indicated a high rate of abuse of the product among teenagers.     

Non-systemic delivery of topical brimonidine to the brain: a neuro-ocular tissue distribution study

To date, the risks of central nervous system (CNS) side effects of topically administered ophthalmic therapeutic agents are thought to be the consequence of systemic absorption of these drugs. This paper envisions the possibility of drug delivery to the CNS following ocular application through non-systemic routes. After single instillation of 50 microl of 3H-radiolabeled Alphagan solution (0.2%) in the cul de sac of the right eye, three male albino rabbits (2-2.5 kg) were sacrificed at each time point (5, 15, 30 and 60 min). Both sides (eyes) specimens of aqueous humor, cornea, iris, lens, vitreous, conjunctiva, sclera, ciliary body, choroid, retina, optic nerve, optic tract and olfactory bulb were weighed, and blood samples were measured, before combustion in tissue oxidizer and radioactive liquid scintillation counting. Significant 3H-brimonidine levels were found in right and left optic nerves and tracts with extremely low corresponding drug levels in blood. Uveal tract (ciliary body, iris and choroid tissues) brimonidine levels were relatively high in the treated eye, and the highest among contralateral eye tissues. Our data provide the first case of good CNS availability after ocular application of conventional ophthalmic therapeutic agent, through non-systemic routes. Similar neuro-ocular pharmacokinetic studies should be adopted as a routine ocular therapeutics evaluation study.     

Non-systemic delivery of topical brimonidine to the brain: A neuro-ocular tissue distribution study

To date, the risks of central nervous system (CNS) side effects of topically administered ophthalmic therapeutic agents are thought to be the consequence of systemic absorption of these drugs. This paper envisions the possibility of drug delivery to the CNS following ocular application through non-systemic routes. After single instillation of 50 μl of ³H-radiolabeled Alphagan® solution (0.2%) in the cul de sac of the right eye, three male albino rabbits (2–2.5 kg) were sacrificed at each time point (5, 15, 30 and 60 min). Both sides (eyes) specimens of aqueous humor, cornea, iris, lens, vitreous, conjunctiva, sclera, ciliary body, choroid, retina, optic nerve, optic tract and olfactory bulb were weighed, and blood samples were measured, before combustion in tissue oxidizer and radioactive liquid scintillation counting. Significant ³H-brimonidine levels were found in right and left optic nerves and tracts with extremely low corresponding drug levels in blood. Uveal tract (ciliary body, iris and choroid tissues) brimonidine levels were relatively high in the treated eye, and the highest among contralateral eye tissues. Our data provide the first case of good CNS availability after ocular application of conventional ophthalmic therapeutic agent, through non-systemic routes. Similar neuro-ocular pharmacokinetic studies should be adopted as a routine ocular therapeutics evaluation study.     

Acute poisoning with a glyphosate-surfactant herbicide ('Roundup'): a review of 93 cases.

Between 1 January 1980, and 30 September 1989, 93 cases of exposure to herbicides containing glyphosphate and surfactant ('Roundup') were treated at Changhua Christian Hospital. The average amount of the 41% solution of glyphosate herbicide ingested by non-survivors was 184 +/- 70 ml (range 85-200 ml), but much larger amounts (500 ml) were reported to have been ingested by some patients and only resulted in mild to moderate symptomatology. Accidental exposure was asymptomatic after dermal contact with spray (six cases), while mild oral discomfort occurred after accidental ingestion (13 cases). Intentional ingestion (80 cases) resulted in erosion of the gastrointestinal tract (66%), seen as sore throat (43%), dysphagia (31%), and gastrointestinal haemorrhage (8%). Other organs were affected less often (non-specific leucocytosis 65%, lung 23%, liver 19%, cardiovascular 18%, kidney 14%, and CNS 12%). There were seven deaths, all of which occurred within hours of ingestion, two before the patient arrived at the hospital. Deaths following ingestion of 'Roundup' alone were due to a syndrome that involved hypotension, unresponsive to intravenous fluids or vasopressor drugs, and sometimes pulmonary oedema, in the presence of normal central venous pressure.     

NBOMe Designer Drug Exposures Reported to Texas Poison Centers

Use of 2-methoxybenzyl analogues of 2C-X phenethylamines (NBOMe) is increasing in the United States. Twenty-five NBOMe exposures reported to Texas poison centers during 2012–2013 were identified; 76% involved 25I-NBOMe, 12% involved 25C-NBOMe, and 12% involved an unknown NBOMe. Eighty-eight percent of the patients were men; mean age was 17 years (range, 14–25 years). The exposure route was 72% from ingestion alone, 12% from inhalation alone, 4% from ingestion and inhalation, and 12% from an unknown route. The most common clinical effects were tachycardia (52%), agitation (48%), hallucinations (32%), hypertension (32%), confusion (24%), and mydriasis (20%). Two patients died.     

Distribution of brimonidine into anterior and posterior tissues of monkey, rabbit, and rat eyes.

The objectives of the study were to evaluate the distribution of brimonidine (alpha2-adrenergic agonist) into anterior and posterior ocular tissues. Single or multiple doses of a 0.2 or 0.5% brimonidine tartrate solution were administered to one or both eyes of monkeys or to one eye of rabbits. Brimonidine was administered intraperitoneally to rats. After topical administration, [14C]brimonidine was rapidly absorbed into the cornea and conjunctiva and distributed throughout the eye. [14C]Radioactivity was higher and cleared more slowly in pigmented tissues (iris/ciliary body, choroid/retina, and optic nerve) than in nonpigmented tissues. Single and multiple dosing led to a similar drug distribution, with higher levels of brimonidine measured in pigmented tissues after multiple dosing. Most of the radioactivity extracted from ocular tissues represented unchanged brimonidine. In the rabbits and the monkey treated in only one eye, levels of radioactivity in the untreated eye were low, consistent with the low systemic levels and rapid drug clearance. Posterior ocular tissue concentrations of radioactivity exceeded systemic blood concentrations. The vitreous humor brimonidine concentrations in monkeys treated topically with 0.2% brimonidine tartrate was 82 +/- 45 nM. Vitreous levels in rabbits confirmed the penetration of brimonidine to the posterior segment. Similar concentrations of brimonidine (22 to 390 nM) were measured in the vitreous and retina of rats injected intraperitoneally with brimonidine. Both topically applied and systemically administered brimonidine reach the back of the eye at nanomolar concentrations sufficient to activate alpha2-adrenergic receptors. The brimonidine levels achieved at the retina are relevant for neuroprotection models.     

Moxifloxacin 0.5% ophthalmic solution: in bacterial conjunctivitis

The fourth-generation 8-methoxyfluoroquinolone moxifloxacin is available as an 0.5% ophthalmic solution for use in the treatment of bacterial conjunctivitis. Moxifloxacin had good activity against various Gram-positive and -negative ocular isolates in vitro, and moxifloxacin 0.5% ophthalmic solution achieved good penetration into ocular tissues in healthy volunteers and patients undergoing ocular surgery. The efficacy of moxifloxacin 0.5% ophthalmic solution in the treatment of bacterial conjunctivitis has been shown in three randomized, double-blind, multicentre trials. In a trial in patients aged ≥1 year, the clinical success rate was significantly higher with moxifloxacin 0.5% ophthalmic solution than with placebo. In a trial in patients aged ≥12 years, moxifloxacin 0.5% ophthalmic solution was noninferior to levofloxacin 0.5% ophthalmic solution in terms of the clinical success rate. In a third trial, the clinical cure rate was significantly higher with moxifloxacin 0.5% ophthalmic solution than with trimethoprim 1.0%/polymixin B 10,000?IU/mL ophthalmic solution in paediatric patients aged ≤18 years. Moxifloxacin 0.5% ophthalmic solution was well tolerated in patients with bacterial conjunctivitis. Ocular adverse events (e.g. eye pain, eye irritation) were the most commonly reported treatment-related adverse events, with the majority being of mild severity.     

Topical bimatoprost: a review of its use in open-angle glaucoma and ocular hypertension

Bimatoprost, a synthetic prostamide analogue, is a new ocular hypotensive agent indicated for the second-line treatment of open-angle glaucoma and ocular hypertension. The drug is formulated as a 0.03% ophthalmic solution. Bimatoprost lowers intraocular pressure (IOP) by increasing aqueous humour outflow. When applied topically once daily in patients with ocular hypertension or glaucoma, bimatoprost 0.03% significantly reduced IOP. Mean IOP was reduced by approximately 7.5 to 9.2mm Hg 12 hours after drug administration in randomised clinical trials. The reduction in IOP was maintained throughout the 24-hour dosage interval. Once-daily treatment with bimatoprost 0.03% was found to be significantly more effective than timolol 0.5% (administered twice daily as an ophthalmic solution or once daily as a gel-forming solution) in randomised comparative trials in patients with ocular hypertension and glaucoma. Furthermore, after 1 to 6 months' treatment, the percentage of patients reaching a target IOP of < or =17mm Hg was significantly greater in the bimatoprost-treated groups than in those receiving timolol. Bimatoprost 0.03% ophthalmic solution was found to be at least as effective as topical latanoprost 0.005% administered once daily in two clinical trials. Reductions in IOP 16 and 20 hours postdose were greater in patients treated with bimatoprost, indicating superior control of IOP at timepoints throughout the dosage interval. In patients refractory to beta-blocker therapy, treatment with bimatoprost 0.03% produced greater reductions in diurnal IOP measurements than combination therapy with topical dorzolamide 2%/timolol 0.5%; approximately twice as many bimatoprost 0.03% recipients achieved an IOP of < or =16mm Hg. The most commonly reported adverse effect during clinical trials of once-daily bimatoprost 0.03% was conjunctival hyperaemia which occurred in 42 to 46% of patients treated. However, most cases were mild and only 1 to 4% of patients withdrew from treatment as a result. Overall withdrawal rates as a result of adverse events during clinical trials ranged from 2.6 to 7%. Bimatoprost has been reported to cause changes in the pigmentation of the periorbital skin, eyelashes and iris, and increase eyelash growth. The long-term consequences of these effects are unknown. Cardiopulmonary adverse effects, which have been associated with the use of beta-blockers such as timolol, were not reported in clinical trials of bimatoprost. Thus, in clinical trials of up to 1-year duration, bimatoprost 0.03% has been found to be effective in significantly lowering IOP and is generally well tolerated. It provides an alternative treatment option for patients in whom beta-blockers are contraindicated. Furthermore, bimatoprost provides an effective second-line treatment option in patients who do not achieve target IOP with other topical ocular hypotensive agents, or who experience unacceptable adverse effects. Wider clinical use of this drug will establish the place of bimatoprost in the treatment of open-angle glaucoma and ocular hypertension.     

曲伏前列素与盐酸左布诺洛尔滴眼液在原发性开角型青光眼治疗中血液流变学的对比研究

目的 探讨曲伏前列素与盐酸左希诺洛尔滴眼液在原发性开角型青光眼治疗中血液流变学的效果.方法 选择80例原发性开角型青光眼患者,通过随机数表法分为曲伏前列素组和盐酸左希诺洛尔组,每组40例,分别使用曲伏前列素滴眼液和盐酸左希诺洛尔滴眼液治疗.观察2组患者治疗前后血液流变学、视力、眼压变化,并比较临床疗效.结果 治疗后,曲伏前列素组全血黏度高切、全血黏度低切、血浆黏度均比盐酸左希诺洛尔组低(P<0.05);视力优于盐酸左希诺洛尔组,治疗后4周、12周眼压均低于盐酸左希诺洛尔组(P<0.05);在治疗后临床疗效中,曲伏前列素总有效率高于盐酸左希诺洛尔组(P<0.05).结论 在原发性开角型青光眼患者中予以曲伏前列素的治疗效果显著,可改善患者血液流变学,并具有降低眼压、提高视力的作用,值得应用推广.     

Drug interaction between cimetidine and timolol ophthalmic solution: effect on heart rate and intraocular pressure in healthy Japanese volunteers

Systemic adverse effects of timolol ophthalmic solution given at usual therapeutic doses have been well characterized. Timolol is partially metabolized by cytochrome P450 (CYP) 2D6. Cimetidine inhibits the activity of cytochrome P450, including CYP2D6, leading to reduced systemic clearance of concomitant drugs. Coadministration of cimetidine has been speculated to affect the pharmacological effects of timolol ophthalmic solution, resulting in increased blood concentration. To evaluate whether administration of cimetidine with timolol ophthalmic solution increased the degree of beta-blockade, 12 healthy Japanese male volunteers ages 19 to 26 received cimetidine (400 mg), on oral placebo, timolol maleate 0.5% (0.05 mL to each eye), or placebo eye drops in a randomized, double-blind, Latin-square design. The oral drug alone was given for 3 days, and on the 4th day, eye drops were applied after oral drug administration. At baseline and 1, 3, and 6 hours after eye drop administration, blood pressure and heart rate (HR) were measured before and after exercise. Intraocular pressure (IOP) was measured at rest. A visual analog scale (VAS) was used to assess subjective bodily feelings in exercise tolerance after every physical exercise. The exercise HR, exercise systolic blood pressure (SBP), and resting SBP were reduced following timolol with and without cimetidine compared with the placebo (p < 0.01, respectively). Administration of cimetidine with timolol ophthalmic solution resulted in additional reductions of the resting HR and IOP. VAS detected a significant reduction in exercise tolerance from timolol ophthalmic solution (p < .05). In conclusion, administration of cimetidine with timolol ophthalmic solution increased the degree of beta-blockade.     

Skeletal muscle relaxant ingestion

We retrospectively analyzed 56 consecutive cases involving acute skeletal muscle relaxant exposure that were reported to the Poison Control Center over a 1-year period. The age range was 9 mo to 56 years (mean 18.9 +/- 13.1) with the site of exposure being the primary residence in 54 cases (96.4%). The reasons for inquiry to the Poison Center were reported to be intentional suicide in 26 cases (46.4%), accidental in 21 cases (37.5%), with intentional misuses in 5 cases (8.9%). No deaths were reported. Eighteen cases (32.1%) were reported with co-ingestants (average number of substances taken was 2.7 +/- 0.8). Of these cases 3 patients (16.7%) had major effects with life-threatening symptoms with 6 (33.3%) patients having no symptoms. Of the remaining 38 cases, 17 (44.7%) wer cyclobenzaprine, 6 (15.8%) were methocarbamol, 5 (13.2%) were carisoprodol, 5 (13.2%) were chlorzoxazone, 3 (7.89%) were Baclofen and the remainder were either life-threatening symptoms (2.6%), while 29 (74.3%) had no or minor effects with symptoms that subsided. We conclude that morbidity and mortality are low in pure skeletal muscle relaxant ingestion, however it may be increased in multiple ingestions.     

Stability of gentamicin sulfate and tobramycin sulfate in extemporaneously prepared ophthalmic solutions at 8 degrees C

The stability of gentamicin sulfate and tobramycin sulfate in fortified ophthalmic solutions stored under refrigeration was studied. Fortified gentamicin ophthalmic solution and fortified tobramycin ophthalmic solution were prepared to a final theoretical concentration of 13.6 mg/mL by using commercially available ophthalmic and injectable solutions. Volumes of each solution were packaged in plastic bottles and refrigerated at 4-8 degrees C. Samples of each solution were analyzed by fluorescence polarization immunoassay on days 0 (before refrigeration), 1, 2, 3, 4, 7, 14, 28, 63, and 91. To validate the method, identical solutions were prepared, stored under refrigeration at 4-8 degrees C, and analyzed by a stability-indicating high-performance liquid chromatographic assay on days 0 (before refrigeration), 9, 28, 56, and 91. Fluorescence polarization immunoassay showed the mean concentrations of gentamicin and tobramycin on day 91 to be 104.4% and 97.4%, respectively, of the time 0 concentrations; the difference was not significant in either case. HPLC validated these results; the mean concentration of gentamicin and tobramycin on day 91 was 103.3% and 101.2%, respectively, of the mean day 0 concentrations. Gentamicin and tobramycin in ophthalmic solutions prepared by mixing ophthalmic and injectable products and stored in plastic bottles at 4-8 degrees C were stable for three months.     

Children's acetaminophen exposures reported to a regional poison control center.

PURPOSE: The patient characteristics, doses taken, and types of exposures in children with acetaminophen-related exposures reported to a regional poison control center (RPCC) were studied. METHODS: A retrospective review was conducted of all acetaminophen exposures that occurred between October 31, 2000, and October 31, 2003, in children younger than 18 years who were managed by an RPCC. Children were grouped into three age categories: less than 6 years (group 1), 6-12 years (group 2), and 13-17 years (group 3). Data collected included patient demographics, drug details, type of exposure, time since exposure, exposure site, and caller site. RESULTS: There were 473 exposures to acetaminophen: 76% in group 1, 3% in group 2, and 21% in group 3. Sex was distributed equally among groups, except group 3 was 83% females. The majority of callers seeking information on acetaminophen ingestion in children younger than 12 years were family members (62%), whereas health professionals (61%) were the most common callers for children over 12 years. Unintentional ingestion was the most common type of exposure in group 1 (100%) and group 2 (93.7%). In group 3, intentional ingestions were more common (91%), with females representing far more of these exposures than males (87% versus 14%, respectively). Acetaminophen doses over 200 mg/kg were ingested by 47% of children in group 3. CONCLUSION: Most acetaminophen exposures reported to an RPCC occurred in children less than six years of age and were unintentional, whereas exposures in children over 12 years were more likely to be intentional overdoses.