brimonidine is an alpha adrenergic agonist represented by the following formula : timolol is a beta adrenergic agent represented by the following formula : brimonidine is available from allergan , inc ., irvine , calif . as an ophthalmic pharmaceutical product having the name alphagan ®. timolol is available from various sources , including merck co ., rahway , n . j . the compositions of the present invention are administered topically . the dosage is 0 . 001 to 1 . 0 , e . g . mg / per eye bid ; wherein the cited mass figures represent the sum of the two components , brimonidine and timolol . the compositions of the present invention can be administered as solutions in a suitable ophthalmic vehicle . in forming compositions for topical administration , the mixtures are preferably formulated as 0 . 01 to 0 . 5 percent by weight brimonidine and 0 . 1 to 1 . 0 percent by weight timolol solution in water at a ph of 4 . 5 to 8 . 0 , e . g . about 6 . 9 . while the precise regimen is left to the discretion of the clinician , it is recommended that the solution be topically applied by placing one drop in each eye two times a day . other ingredients which may be desirable to use in the ophthalmic preparations of the present invention include preservatives , co - solvents and viscosity building agents . ophthalmic products are typically packaged in multidose form . preservatives are thus required to prevent microbial contamination during use . suitable preservatives include : benzalkonium chloride , thimerosal , chlorobutanol , methyl paraben , propyl paraben , phenylethyl alcohol , edetate disodium , sorbic acid , onamer m , or other agents known to those skilled in the art . in the prior art ophthalmic products , typically such preservatives are employed at a level of from 0 . 004 % to 0 . 02 %. in the compositions of the present application the preservative , preferably benzalkonium chloride , may be employed at a level of from 0 . 001 % to less than 0 . 01 %, e . g . from 0 . 001 % to 0 . 008 %, preferably about 0 . 005 % by weight . it has been found that a concentration of benzalkonium chloride of 0 . 005 % is sufficient to preserve the compositions of the present invention from microbial attack . this concentration may be advantageously compared to the requirement of 0 . 01 % benzalkonium chloride to preserve timolol in the individual , commercially - available ophthalmic products . moreover , it has been found that adequate lowering of intraocular pressure has been obtained when administering the compositions of this invention twice a day as compared to the fda - approved regimen wherein brimonidine ophthalmic solution , i . e . alphagan ® ophthalmic solution is administered three times a day and timolol ophthalmic solution , i . e . timoptic ® ophthalmic solution is administered twice a day . this results in the exposure of the patient to 67 % and 50 % of benzalkonium chloride , with the compositions of this invention , as compared to the administration of alphagan ® and timoptic ®, respectively . in fda - approved adjunctive therapy , wherein alphagan ® and timoptic ® are serially administered , the patient is exposed to almost three times the concentration of benzalkonium chloride as compared to the administration of the compositions of this invention twice a day . ( it is noted that it is known that benzalkonium chloride at high concentrations is cytotoxic . therefore , minimizing the patient &# 39 ; s exposure to benzalkonium chloride , while providing the preservative effects afforded by benzalkonium chloride , is clearly desirable .) the solubility of the components of the present compositions may be enhanced by a surfactant or other appropriate co - solvent in the composition . such cosolvents include polysorbate 20 , 60 , and 80 , pluronic f68 , f - 84 and p - 103 , cyclodextrin , or other agents known to those skilled in the art . typically such co - solvents are employed at a level of from 0 . 01 % to 2 % by weight . viscosity increased above that of simple aqueous solutions may be desirable to increase ocular absorption of the active compound , to decrease variability in dispensing the formulation , to decrease physical separation of components of a suspension or emulsion of the formulation and / or to otherwise improve the ophthalmic formulation . such viscosity building agents include as examples polyvinyl alcohol , polyvinyl pyrrolidone , methyl cellulose , hydroxy propyl methylcellulose , hydroxyethyl cellulose , carboxymethyl cellulose , hydroxy propyl cellulose or other agents known to those skilled in the art . such agents are typically employed at a level of from 0 . 01 % to 2 % by weight . the present invention further comprises an article of manufacture comprising packaging material and a pharmaceutical agent contained within said packaging material , wherein the pharmaceutical agent is therapeutically effective for lowering intraocular pressure and wherein the packaging material comprises a label which indicates the pharmaceutical agent can be used for lowering intraocular pressure and wherein said pharmaceutical agent comprises an effective amount of brimonidine and an effective amount of timolol . the following example is a representative pharmaceutical composition of the invention for topical use when indicated for treating glaucoma . brimonidine tartrate 0 . 20 % ( w / v ) and timolol maleate 0 . 68 % ( w / v ) ( equivalent to 0 . 50 % ( w / v ) timolol ) the brimonidine - timolol combination formulation presented in the table , below , is a sterile , preserved , aqueous solution . the formulation vehicle is based upon a timolol ophthalmic solution which contains an isotonic phosphate buffer system at ph 6 . 9 . the formulation preservative is benzalalkonium chloride ( bak ) at a concentration of 0 . 005 % ( w / v ) ( 50 ppm ). the formulation passes regulatory required preservative efficacy testing ( pet ) criteria for usp ( united states pharmacopoeia ) and ep ( european pharmacopoeia - a and - b over 24 months . the pharmaceutical composition of example i is used in the clinical study reported below . to compare the safety and efficacy of twice - daily dosed brimonidine tartrate 0 . 2 %/ timolol 0 . 5 % ophthalmic solution combination ( henceforth referred to as combination ) with that of twice - daily dosed timolol ophthalmic solution 0 . 5 % ( henceforth referred to as timolol ) and three - times - daily dosed alphagan ® ( brimonidine tartrate ophthalmic solution ) 0 . 2 % ( henceforth referred to as brimonidine ) administered for three months ( plus 9 - month masked extension ) in patients with glaucoma or ocular hypertension . randomization : patients were randomized to one of the 3 masked treatment groups ( combination , brimonidine or timolol ) based on an even allocation at each site ; visit schedule : prestudy , baseline ( day 0 ), week 2 , week 6 , month 3 , month 6 , month 9 , and month 12 . 560 planned to enroll ; 586 enrolled ( combination = 193 , brimonidine = 196 , timolol = 197 ); 502 completed . mean ( range ) age : 62 . 4 ( 23 to 87 ) years ; 46 . 1 % ( 270 / 586 ) males , 53 . 9 % ( 316 / 586 ) females . diagnosis : ocular hypertension , chronic open - angle glaucoma , chronic angle - closure glaucoma with patent iridotomy , pseudoexfoliative glaucoma or pigmentary glaucoma and requiring bilateral treatment ; key inclusion criteria : ≧ 18 years , day 0 ( post - washout ) intraocular pressure ( iop )≧ 22 mm hg and ≦ 34 mm hg in each eye and asymmetry of iop ≦ 5 mm hg , best - corrected early treatment of diabetic retinopathy study ( etdrs ) visual acuity equivalent to a snellen score of 20 / 100 or better in each eye ; key exclusion criteria : uncontrolled systemic disease , abnormally low or high blood pressure or pulse rate for age or contraindication to beta - adrenoceptor antagonist therapy , anticipated alteration of existing chronic therapy with agents which could have a substantial effect on iop , contraindication to brimonidine therapy , allergy or sensitivity to any of the study medication ingredients , anticipated wearing of contact lenses during the study , laser surgery , intraocular filtering surgery or any other ocular surgery within the past 3 months , or required chronic use of other ocular medications during the study ( intermittent use of artificial tear product was allowed ). brimonidine tartrate 0 . 2 %/ timolol 0 . 5 % combination ophthalmic solution one drop (˜ 35 μl ) instilled in each eye bid in the morning and evening ; and vehicle of the combination ophthalmic solution , one drop (˜ 35 μl ) instilled in each eye once daily ( qd ) in the afternoon ( for masking purposes ). active control alphagan ® ( brimonidine tartrate ophthalmic solution ) 0 . 2 %, one drop (˜ 35 μl ) instilled in each eye tid in the morning , afternoon , and evening . active control timolol ophthalmic solution 0 . 5 %, one drop (˜ 35 μl ) instilled in each eye bid in the morning and evening ; and vehicle of the combination ophthalmic solution , one drop (˜ 35 μl ) instilled in each eye once daily ( qd ) in the afternoon ( for masking purposes ). efficacy : iop ( hours 0 , 2 , 7 , and 9 ), patient satisfaction questionnaire , patient comfort of study medication questionnaire , pharmacoeconomic evaluation by investigator ; safety : adverse events ( ae ), biomicroscopy , visual acuity ( va ), visual field , ophthalmoscopy , cup / disc ratio , heart rate , blood pressure , hematology , serum chemistry , urinalysis and pregnancy test ; other : quantitation of plasma brimonidine and timolol concentrations ( at selected sites ), resource utilization ( to be reported upon completion of the 1 year study ). all data were summarized with descriptive statistics , frequency tables , and / or data listings . safety analyses included all patients who received at least 1 dose of study medication . analyses were performed for the primary efficacy variable iop using the intent - to - treat ( itt ) population with last observation carried forward ( locf ), and the per protocol population with observed cases . ordinal categorical variables were analyzed by the wilcoxon rank - sum test . nominal categorical variables were analyzed using fisher &# 39 ; s exact or pearson &# 39 ; s chi - square tests . within - group changes from baseline for categorical variables were analyzed using the wilcoxon signed - rank test . continuous variables ( eg , iop ) were analyzed using analysis of variance ( anova ). within - group changes from baseline for continuous variables were analyzed using paired t - tests . a 2 - way anova model with factors for treatment and investigator was used for the analysis of iop . comparisons were made between the combination and each of the 2 monotherapies in a pairwise fashion using contrasts from the anova model , with the same error term . a separate anova model was employed at each hour / visit measurement of iop . each of the 2 null hypotheses ( combination versus timolol and combination versus brimonidine ) was tested at the 0 . 05 significance level . point estimates of the mean treatment differences , as well as 2 - sided 95 % confidence intervals ( ci ) of the difference , were provided at each timepoint . efficacy : at baseline , mean values of diurnal iop ranged from 22 . 2 mm hg to 24 . 9 mm hg in the combination group , 22 . 5 mm hg to 25 . 0 mm hg in the brimonidine group , and 22 . 3 mm hg to 24 . 8 mm hg in the timolol group . there were no statistically significant differences between treatment groups . mean changes from baseline diurnal iop at week 2 , week 6 and month 3 ranged from : the mean decreases from baseline diurnal iop were statistically significant within each treatment group at each follow - up timepoint ( p & lt ; 0 . 001 ). the mean decrease from baseline diurnal iop was statistically significantly greater with combination than with brimonidine at hours 0 , 2 , and 7 at all follow - up visits ( p & lt ; 0 . 001 ). in addition , clinically significant differences of more than 1 . 5 mm hg in mean change from baseline iop favoring combination over brimonidine were seen at hours 0 , 2 , and 7 at all follow - up visits . at hour 9 , the decreases from baseline diurnal iop were greater for the combination group than the brimonidine group at all follow - up visits , although the differences were not statistically significant ( p ≧ 0 . 104 ). the mean decrease from baseline diurnal iop was statistically significantly greater with combination than with timolol at hours 0 , 2 , 7 and 9 at all follow - up visits ( p ≦ 0 . 041 ). in addition , clinically significant differences of more than 1 . 5 mm hg in mean change from baseline iop favoring combination over timolol were seen at week 2 ( hours 0 , 2 , and 7 ), week 6 ( hours 2 and 7 ), and month 3 ( hours 0 and 2 ). mean values of diurnal iop at week 2 , week 6 and month 3 ranged from : mean values of diurnal iop were statistically significantly less with combination than with brimonidine at hours 0 , 2 , and 7 at all follow - up visits ( p & lt ; 0 . 001 ) and at hour 9 at week 6 and month 3 ( p ≦ 0 . 011 ). the mean values of iop at hour 9 at week 2 were lower for the combination group than the brimonidine group , although the difference was not statistically significant ( p = 0 . 205 ). in addition , clinically significant differences of more than 1 . 5 mm hg in mean iop favoring combination over brimonidine were seen at hours 0 , 2 , and 7 at all follow - up visits and at hour 9 at month 3 . mean values of diurnal iop were statistically significantly less with combination than with timolol at hour 0 at week 2 and month 3 ; and at hours 2 , 7 and 9 at all follow - up visits ( p ≦ 0 . 050 ). the mean values of iop at hour 0 , week 6 , were lower for the combination group than the timolol group , although the difference was not statistically significant ( p = 0 . 102 ). in addition , clinically significant differences of more than 1 . 5 mm hg in mean iop favoring combination over timolol were seen at week 2 ( hours 0 , 2 , and 7 ), week 6 ( hours 2 , 7 , and 9 ), and month 3 ( hours 2 and 9 ). at the month 3 or exit visit , a statistically significantly greater “ yes ” response to the investigator pharmacoeconomic evaluation was recorded for patients receiving combination ( 91 . 1 %, 173 / 190 ) than for patients receiving brimonidine ( 73 . 4 %, 141 / 192 , p & lt ; 0 . 001 ). a “ yes ” response was recorded for 92 . 7 % ( 179 / 193 ) of patients receiving timolol . there were no statistically significant differences in the change from baseline in treatment comfort between combination and each of the monotherapy groups . treatment satisfaction was better than baseline for a statistically significantly greater percentage of patients in the combination group ( 23 . 4 %, 36 / 154 ) than in the brimonidine group ( 13 . 2 %, 20 / 151 , p = 0 . 005 ). a total of 19 . 9 % ( 30 / 151 ) of patients in the timolol group reported better treatment satisfaction than baseline . through month 3 of the study , 53 . 4 % ( 103 / 193 ) of patients in the combination group , 61 . 7 % ( 121 / 196 ) of the brimonidine group , and 50 . 8 % ( 100 / 197 ) of the timolol group experienced one or more adverse events , regardless of causality . the incidences of oral dryness , eye pruritus , foreign body sensation and conjunctival folliculosis were statistically significantly lower with the combination than with brimonidine ( p ≦ 0 . 034 ), while burning and stinging were statistically significantly higher with the combination than with brimonidine ( p ≦ 0 . 028 ). there were no statistically significant differences in adverse events between the combination and timolol , except for a statistically significantly higher incidence of eye discharge with the combination ( 2 . 6 %, 5 / 193 ) compared to timolol ( 0 %, 0 / 197 ; p = 0 . 029 ). the most frequently reported adverse events (& gt ; 3 % in any treatment group ) were as follows , tabulated by descending order in the combination group : adverse events led to the discontinuation of 3 . 6 % ( 7 / 193 ) of patients in the combination group , similar to 3 . 0 % ( 6 / 197 ) of patients in the timolol group , and statistically significantly less than 14 . 3 % ( 28 / 196 ) of patients in the brimonidine group ( p & lt ; 0 . 001 ). serious adverse events were reported for 1 . 0 % ( 2 / 193 ) of patients in the combination group , 2 . 0 % ( 4 / 196 ) of patients in the brimonidine group , and 2 . 0 % ( 4 / 197 ) of patients in the timolol group . two patients receiving timolol had 4 serious adverse events ( emphysema in one patient ; nausea , sweating , and tachycardia in the other patient ) which were considered possibly related to the study drug . there was 1 death in the brimonidine group , possibly due to complications from cardiac surgery , and not related to study drug . there were no clinically relevant differences between the combination and either of the individual components in the mean change from baseline to month 3 for any hematology , chemistry , or urinalysis parameter . statistically significant ( p ≦ 0 . 048 ) within - group changes from baseline were found , but were small and not clinically relevant . small but statistically significant ( p ≦ 0 . 001 ) mean reductions in heart rate ranging from − 2 . 1 to − 3 . 7 bpm were seen with the combination , similar to timolol . small but statistically significant ( p ≦ 0 . 003 ) mean reductions in blood pressure at hour 2 ( postdose ) were seen with the combination , similar to brimonidine . these small changes in mean heart rate and blood pressure were associated with clinical symptoms in only a few patients . increases from baseline in the severity of conjunctival erythema and conjunctival follicles on biomicroscopy were statistically significantly less with the combination than with brimonidine ( p ≦ 0 . 011 ). the majority of patients in each treatment group showed less than a 2 - line change from baseline visual acuity . there were no significant between - group differences for changes in visual fields or cup / disc ratio . blood samples were available for 55 patients in the combination group , 49 patients in the brimonidine group , and 54 patients in the timolol group . all samples were assayed for both brimonidine ( lower limit of quantitation [ lloq ] 5 pg / ml ) and timolol ( lloq 5 pg / ml ). plasma brimonidine and timolol concentrations were not quantifiable in all but 1 sample on day 0 , hour 0 for both combination and the monotherapy treatment groups . in the combination group , mean ± standard deviation ( sd ) plasma brimonidine concentrations 1 hour postdose at week 2 and month 3 were 49 . 7 ± 36 . 1 and 52 . 8 ± 46 . 7 pg / ml , respectively . in the brimonidine group , mean ± sd plasma brimonidine concentrations at week 2 and month 3 were 81 . 0 ± 63 . 8 and 78 . 6 ± 48 . 9 pg / ml , respectively . in the combination group , mean ± sd plasma timolol concentrations at week 2 and month 3 were 0 . 499 ± 0 . 327 and 0 . 586 ± 0 . 580 ng / ml , respectively . in the timolol group , mean ± sd plasma timolol concentrations at week 2 and month 3 were 0 . 950 ± 0 . 709 and 0 . 873 ± 0 . 516 ng / ml , respectively . plasma brimonidine and timolol concentrations 1 hour postdose were steady and did not increase over the 3 - month study duration . brimonidine concentrations were 39 %, 34 % and 39 % lower in the combination group than in the monotherapy group at week 2 ( p = 0 . 004 ), month 3 ( p = 0 . 013 ), and month 12 , respectively . timolol concentrations were 47 % and 33 % lower in the combination group than in the monotherapy group at week 2 ( p & lt ; 0 . 001 ) and month 3 ( p = 0 . 011 ), respectively . timolol concentrations were also significantly lower in the combination treatment group than in the timolol monotherapy treatment group ( p = 0 . 0006 ). timolol concentrations were 49 %, 32 %, and 21 % lower in the combination group than in the monotherapy group at week 2 , month 3 , and month 12 , respectively . the plasma brimonidine concentration in males was statistically significantly lower than in females for the brimonidine group ( 37 % lower at week 2 [ p = 0 . 034 ] and 37 % lower at month 3 [ p = 0 . 017 ]); the difference was not statistically significant in the combination group . the plasma timolol concentration in males was statistically significantly lower than in females for both the combination group ( not statistically significant at week 2 ; 52 % lower at month 3 [ p = 0 . 012 ]) and the timolol group ( 45 % lower at week 2 [ p = 0 . 006 ] and 39 % lower at month 3 [ p = 0 . 003 ]). plasma brimonidine concentration in the elderly group was not significantly different from in the young group for the combined data from both the combination and brimonidine treatment groups ( p - value = 0 . 1323 ). however , plasma timolol concentration in the young group was significantly lower than in the elderly group for combined data from both the combination and the timolol treatment groups ( p - value = 0 . 0005 ). the combination treatment ( brimonidine tartrate 0 . 2 %/ timolol 0 . 5 %) administered bid for 3 months was superior to timolol ( timolol 0 . 5 %) bid and brimonidine ( brimonidine tartrate 0 . 2 %) tid in lowering the elevated iop of patients with glaucoma or ocular hypertension . the combination administered bid demonstrated a favorable safety profile that was comparable to timolol bid and better than brimonidine tid with regard to the incidence of adverse events and discontinuations due to adverse events . the invention has been described herein by reference to certain preferred embodiments . however , as obvious variations thereon will become apparent to those skilled in the art , the invention is not to be considered as limited thereto .
disclosed are pharmaceutical compositions comprising brimondine and timolol for topical ophthalmic delivery and a method of treatment comprising administering said composition when indicated for glaucoma and associated conditions such as elevated intraocular pressure in the eyes of humans .