in order to obtain adequate long - term stability , appropriate containers must be used for the solution of diphosphonate . appropriate containers for this product include ampoules , vials , bottles , ready to use syringes and shell glass vials . it is believed that the principal cause of turbidity where glass containers have been used in the past is the leaching out from the glass of aluminium and / or other cations such as magnesium or calcium , depending upon the glass composition . where glass containers are used it is necessary to pre - treat the contact surface of the glass with an appropriate method to protect against the leaching of impurities from the glass by the solution . preferably all potential contact surfaces will be appropriately treated . in this way , the extent to which impurities leach from the glass over time is reduced . a preferred method of pre - treatment is a siliconization process using a one percent silicone solution to wash the vials , followed by double draining and heating at 310 ° c . for thirty minutes . vials pretreated in this manner are available from the french vial manufacturer saint - gobain desjonqueres ( sgd ). other vial pretreatment techniques include the use of a high purity sio 2 barrier formed on the inside vial surface by a plasma - deposition process . the process involves microwave energy being applied to a silicon containing precursor in the presence of oxygen . a plasma forms and a sio 2 layer is formed on the glass surface from the gas phase . vials pretreated in this manner are available from schoft . in addition to treating the surface of the glass , it is also recommended to use containers which are made from glass having a low aluminium content . glass typically used for pharmaceutical vials has in the order of 5 percent aluminium oxide . in order to reduce the problem of aluminium ion leaching , glass with lower aluminium content is recommended . where the solution is stored in a stoppered vial , the stopper provides a potential source of contamination . typical elastomeric stoppers are potentially a source of metal ions eg calcium , zinc and magnesium ions which can react with the diphosphonate to form insoluble matter . in order to reduce the possibility of contamination , stoppers with low levels of these ions and other potential contaminants are to be used , preferably coated to form an inert barrier . an example of an appropriate stopper is the daikyo d777 - 1 stopper . daikyo d777 - 3 stoppers may also be used . preferably the stopper has a low calcium , magnesium and ash content and is at least coated on the contact surface ( being the surface of the stopper which when placed in a vial is exposed to the contents of the vial ) with a fluorinated resin such as tetrafluoroethylene polymer , trifluorochloroethylene polymer , tetrafluoroethylene - hexafluoropropylene copolymer , fluorovinylidene polymer , vinylidene fluoride polymer , vinyl fluoride polymer , tetrafluoroethylene - ethylene copolymer , ethylene - tetrafluoroethylene copolymer , or perfluoroalkoxy polymer . it is more preferred that the stopper is coated with a fluorinated resin selected from a group consisting of tetrafluoroethylene polymer , trifluorochloroethylene polymer , tetrafluoroethylene - hexafluoropropylene copolymer , vinylidene fluoride polymer , vinyl fluoride polymer , and tetrafluoroethylene - ethylene copolymer . for example , the stopper can be a flurotec ® stopper manufactured by daikyo and distributed by west pharmaceuticals services . containers , such as vials , may be constructed from any suitable other materials in addition to glass , such as polyethylene , polypropylene and polymethylpentene . for example , the vial could be constructed from crystal zenith ® resin as manufactured by west pharmaceuticals services . this invention is generally applicable to all diphosphonates . specifically , this includes solutions of pamidronate , zolindronate , chlodronate , etidronate , alendronate and tiludronate . these can be prepared from their respective diphosphonic acid form or from a therapeutically acceptable salt form . the acids of the above diphosphonates are : pamidronic acid [( 3 - amino - 1 - hydroxypropylidene ) diphosphonic acid ], zoledronic acid [( 1 )- hydroxy - 2 -( 1h - imidazol - 1 - yl ) ethylidene ) diphosphonic acid ]; chlodronic acid [ dichloromethylene disphosphonic acid ]; etidronic acid [( 1 - hydroxyethylidene ) diphosphonic acid ]; alendronic acid [( 4 - amino - 1 - hydroxy - butylidene diphosphonic acid ]; and tiludronic acid [[(( p - chloro - phenyl ) thio ) methylene ] diphosphonic acid ] respectively . this invention is particularly applicable to pamidronate and zolendronate . it is preferred to have a product within the biological ph range i . e . of between about 5 and 8 , to reduce the incidence of potential adverse reactions relating to acidic or alkaline solutions . surprisingly it has been found that a stable solution can be produced having a ph of 5 - 8 . a ph level of approximately 6 . 5 is preferred . at ph levels below about 5 there is a risk of producing venous type irritations and other unwanted side effects . ph levels above about 8 give rise to generally unacceptable levels of turbidity . solutions of diphosphonates will generally have a ph above that desired . for example , a solution of one percent pamidronate disodium salt in distilled water has a ph of approximately 8 . 3 . the ph is adjusted with a suitable acid or alkali . suitable acids include any acid such as hydrochloric or phosphoric acid . phosphoric acid is preferred . suitable alkalis include sodium hydroxide . as the person skilled in the art will appreciate , other standard components , such as sugar alcohols and sodium chloride and water may be included in the solution , as required . mannitol is the preferred sugar alcohol . pamidronate solutions are preferably prepared by slowly adding sodium hydroxide solution to a suspension of pamidronic acid in water in a 2 : 1 molar ratio of sodium hydroxide to pamidronic acid , adding mannitol if desired , mixing by stirring until both pamidronic acid and mannitol ( if appropriate ) are completely dissolved and adjusting the ph with phosphoric acid and if necessary sodium hydroxide solution . preferably the preparation of the solutions is carried out under nitrogen . other diphosphonate solutions can be prepared in analogous fashion . to a mixing vessel approximately 10 % of the required amount of water for injection is added and then bubbled with nitrogen gas for at least 15 minutes . the sodium hydroxide , in an amount to give a 2 : 1 molar ratio to pamidronic acid is then added with stirring to dissolve and the solution cooled to less than 30 ° c . a different closed mixing vessel is flushed with nitrogen gas for at least 15 minutes . approximately 70 % of the water for injection is added to the closed mixing vessel through a port and the mixing bubbled with nitrogen gas for at least 15 minutes . pamidronic acid is then added to the mixing vessel with stirring and mixed for 5 minutes giving a suspension . the sodium hydroxide solution is then added over a 5 minute period with stirring to give a clear solution . mannitol is then added to the solution with stirring for at least 5 minutes until dissolved . the ph is then checked and adjusted to a range of between 5 and 8 preferably , between 6 . 3 and 6 . 7 by addition of 1 . 0n phosphoric acid at the rate of approximately 12 . 1 g / l ( calculated on total batch size ) and if necessary 1 . 0n sodium hydroxide , whilst keeping the temperature between 35 ° c . and 45 ° c . the volume is adjusted to the required level with water for injection and the solution cooled to below 30 ° c . the ph is then rechecked and adjusted if necessary to between 6 . 3 and 6 . 7 , with 1 . 0n phosphoric acid or 1 . 0n sodium hydroxide if and as necessary . pamidronic acid 2 . 53 mg mannitol 47 . 0 mg sodium hydroxide 0 . 43 mg ph qs to 6 . 3 - 6 . 7 using 1 . 0n sodium hydroxide or 1 . 0n phosphoric acid water for injection qs to 1 . 0 ml the formulated solution was filled into 10 ml siliconised , low aluminium , type i glass vials , supplied by sgd . each vial was enclosed by a 20 mm , s10 - f451 , d777 - 1 , b2 - 40 , flurotec ® stopper supplied by west pharmaceuticals services . table 1 shows the test results measured over a 24 month period while being stored inverted at 25 ° c ., relative humidity ( rh ) 60 %. the formulated solution was filled into 10 ml siliconised , low aluminium , type i glass vials , supplied by sgd . each vial was enclosed by a 20 mm , sio - f451 , d777 - 1 , b2 - 40 , flurotec ® stopper supplied by west pharmaceuticals services . table 2 shows the test results measured over a 24 month period while being stored inverted at 25 ° c ., relative humidity ( rh ) 60 %. the formulated solution was filled into 10 ml siliconised , low aluminium , type i glass vials , supplied by sgd . each vial was enclosed by a 20 mm , s10 - f451 , d777 - 1 , b2 - 40 , flurotec ® stopper supplied by west pharmaceuticals services . table 3 shows the test results measured over a 21 month period while being stored inverted at 25 ° c ., relative humidity ( rh ) 60 %. the formulated solution was filled , into 10 ml siliconised , low aluminium , type i glass vials , supplied by sgd . each vial was enclosed by a 20 mm , s10 - f451 , d777 - 1 , b2 - 40 , flurotec ® stopper supplied by west pharmaceuticals services . table 4 shows the test results measured over a 21 month period while being stored inverted at 25 ° c ., relative humidity ( rh ) 60 %. it is understood that various modifications , alternatives and / or additions may be made to the product specifically described herein without departing from the spirit and ambit of the invention . throughout the description and claims of this specification the word “ comprise ” and variations of that word such as “ comprises ” and “ comprising ” are not intended to exclude other additives , components , integers or steps .
a pharmaceutical product containing pamidronate and other diphosphonate solutions in an appropriate container , a ph of between 5 and 8 and without organic acid buffer or polyethylen glycol . the container may be treated glass or made of other appropriate material . coated elastomeric stoppers are also included . a method of producing a pharmaceutical product comprising steps of making a suspension of pamadronic acid , adding sodium hydroxide , to form a solution adjusting the ph to between 5 and 8 and transferring the solution to a container .