Stopper “Pop-Up” and the Effects on Container Closure of Sterile Vials

LIGHTHOUSE The Science of Pharmaceutical Manufacturing

Application Note 101 Stopper “Pop-Up” and the Effects on LIGHTHOUSE The Science of Pharmaceutical Manufacturing Container Closure of Sterile Vials LIGHTHOUSE Application Note 101 The Science of Pharmaceutical Manufacturing Stopper “Pop-Up” and the Effects on Container Closure of Sterile Vials

Introduction Container closure integrity plays an impor- Prior to sealing finished vials at the end of sec- tant role in maintaining the stability and ondary drying, a lyophilization chamber is sterility of lyophilized products. The in- backfilled to a gas pressure that is specified for creased number of biological products com- the vial headspace. The specified headspace ing to market and the need to extend product pressure varies from product to product. Typi- shelf life has driven the growth of lyophiliza- cally, freeze dried products are stoppered at ei- tion capacity worldwide. Lyophilization is a ther full vacuum (0 mbar absolute pressure) or complex process that presents many manu- partial vacuum (typically 750 mbar absolute facturing challenges one of which is main- pressure). The vacuum level serves the practical taining and monitoring container closure purpose of helping to seat the stopper and to integrity. Recent attention to package integ- facilitate reconstitution. Once equilibrium is rity issues can be seen in both the revised achieved, the gas pressure in the vial headspace aseptic processing guidance from the regula- matches the chamber pressure and the shelves tory agencies (for example, Annex 1 revisions are lowered to seat the stoppers into the vial. At to the European Guidelines for the Manufac- this point the vial closure integrity is estab- ture of Sterile Products) and an increasing lished but not considered complete until the number of package integrity related product aluminum overseal is applied. Once the shelves recalls. Concerns over the number of custom- are raised, the seal integrity must be main- er complaints and the cost of investigations tained for a period of time ranging from min- and recalls has motivated investment in utes to hours to possibly days before unloading container closure inspection systems by the and capping occur. It is possible during this industry as a means of building quality into time for stoppers to “pop-up” allowing gas in-

manufacturing operations. gress into the vial headspace. Stoppers can pop up due to a number of reasons including im-

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proper seating during shelf lowering, out of pressure rises which may impact the ability to specification stopper and/or vial flange dimen- reconstitute the product and would likely re- sions, and stopper coatings. sult in a customer complaint. Second, if the product is oxygen sensitive then air ingress will If seal integrity is lost during this time period result in oxygen exposure and potentially im- then the physical properties of the headspace pact the product stability. Third, if container (gas pressure and/or composition) will change closure integrity is breached then sterility can as gas from the ambient environment outside no longer be assured. the vial ingresses into the vial headspace. Two common situations serve to illustrate the point. In-process monitoring systems, based on laser If the vial is exposed to a nitrogen atmosphere, absorption spectroscopy, now exist that can for example prior to unloading from the freeze nondestructively monitor each vial for changes dryer, then nitrogen gas will enter the head- in the headspace gas composition and pressure. space causing the pressure to rise. If the vial is These systems are in routine use in the industry exposed to an air atmosphere, either because for inspecting container closure integrity in the chamber was vented with sterile air or be- freeze dried product and, in particular, for ad- cause the vial was exposed to room air prior to dressing the stopper pop-up issue. capping, then air will ingress into the vial causing both the pressure and the oxygen concen- Measurement method tration to rise. The practical implications of lost Laser absorption spectroscopy is a nondestruc- seal integrity are threefold. First, the headspace tive method for monitoring pressure, oxygen

Container Figure 1. Overview of nonde- (Tubing, Molded, Clear, Amber) structive headspace measurement method

Laser Detector diode

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and moisture in the headspace of parenteral changes in the headspace condition of a grossly containers. The method was first introduced to leaking vial occur within minutes. A micro-leak the pharmaceutical industry in the late 1990’s (< 1 micron) will exhibit detectable changes in and has been adopted and validated by compa- the headspace after a few hours to a few days de- nies around the world for both sterile develop- pending on the initial headspace conditions. ment and manufacturing applications. Both headspace pressure rise and oxygen in- Container closure integrity in particular can be gress can be nondestructively monitored by la- monitored nondestructively by headspace gas ser absorption spectroscopy. analysis. Changes in the gas pressure or gas composition are leak indicators. For vials stop- Systems for nondestructive headspace analy- pered under vacuum, a leak causes a rise in sis using laser absorption spectroscopy are headspace pressure towards atmospheric lev- configured as shown in Figure 1. Laser light els. For vials stoppered at or near atmospheric passes through the headspace of a vial and the pressure and exposed to air, a leak causes oxy- laser wavelength is tuned to match the absorp- gen ingress into the vial headspace. The leak tion wavelength of oxygen at 760 nanometers rates that result in pressure rise or oxygen in- or moisture at 1400 nanometers. Oxygen con- gress are dependent on vial volume and pressure differ- Figure 2. Headspace ential. In general the head- inspection systems incorpo- rating the laser measure- space pressure and oxygen ment technology concentration of small volume parenterals (e.g. 3-10mL) packaged under vacuum rise more quickly than the headspace pressure and oxygen concentration of large vol-

ume parenterals packaged near atmosphere. Detectable

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centration is proportional to the amplitude of tions or in-process monitoring of small the laser absorption signal and total gas pres- (<5000) batches of containers. Automated sure is proportional to the width of the laser systems are configured for 100% inspection ap- absorption signal. Systems are calibrated us- plications when batch sizes are large. ing NIST traceable standards with known pressure and oxygen concentration. Case study 1 In the case studies described below non-de- The first case study involves an investigation of structive headspace gas analysis systems from container closure integrity for an oxygen sensi- LIGHTHOUSE were used to monitor container tive lyophilized product stoppered with a ni- closure integrity for commercial batches of ly- trogen headspace near atmospheric pressure ophilized product. Systems, shown in Figure 2, (800 mbar). A number of vials from a com- can be configured for manual operation or in- mercial batch showed elevated levels of oxygen line automated operation. Manually loaded during routine QC analysis using a destructive systems are useful for conducting investiga- oxygen analysis method. A decision was made

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4 4 2 Headspace Oxygen (%)

2 Headspace Oxygen (%) 0 0 0 50 100 150 200 250 0 50 100 150 200 250 Sample # Sample # Figure 3. Headspace oxygen content of vials located Figure 4. Headspace oxygen content of vials located in zones 4-6. Vials from this location in the freeze in zones 1-3. Vials in these locations show air ingress dryer showed no evidence of stopper pop up. due to stopper pop-up.

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to test the entire batch using nondestructive head- sure integrity of two different vial stopper combina- space oxygen analysis. tions under actual in-process conditions. The same A LIGHTHOUSE FMS-Oxygen Headspace Analyzer was vial was evaluated with a grey butyl and a teflon coat- used to test the entire batch for the presence of oxy- ed stopper. The lyophilized product was specified to gen in the vial headspace. Vials with greater than 1% be stoppered at 414 torr (550 mbar) of nitrogen. The oxygen were to be rejected. study evaluated each vial stopper combination for Figure 3 shows the headspace oxygen concentration its ability to hold vacuum. The study used 1000 prod- in vials of freeze dried product that have maintained uct filled vials (500 with each type of closure) distrib- seal integrity. The headspace oxygen levels are all be- uted over 8 shelves (4 shelves with each type of clo- low 1%. Figure 4 shows a very different situation for a sure). set of vials from the same batch of product. One dif- Figure 5 shows the headspace pressure in vials of ference between the two sample sets was their physi- freeze dried product stoppered with a grey butyl cal location inside the lyophilizer. In Figure 4 over elastomeric closure at 414 torr (550 mbar). All of 10% of the vials have lost seal integrity as evidenced by headspace oxygen levels ranging from 1.5% to 10%. 75It0 is Nitrogen Headspace Pressure believed that the root cause of the container closure700 Product samples using rubber butyl stoppers integrity failures was due to stoppers not properly650 750 seated when the lyophilization chamber shelves were600 700

Shelf5 550 650 Shelf6 lowered. This allowed air to ingress at different rates Shelf7 Shelf8 600 UpperSpecification (650 Torr) 500 Target (413.7 Torr, 8psia) resulting in oxygen concentrations over a broad LowerSpecification (350 Torr) Shelf5 550 Shelf6 450 Shelf7 range. The dependence of bad seal integrity on posi- Shelf8 UpperSpecification (650 Torr) 400 500 Target (413.7 Torr, 8psia) tion in the freeze dryer allowed the manufacturer to LowerSpecification (350 Torr)

350 450 troubleshoot mechanical stoppering issues at specif- FrontLPressure (Torr) eft FrontRight Back Left Back Right Corner Corner Corner Corner 300 400 ic locations. 350 FrontLeft FrontRight Back Left Back Right Corner Corner Corner Corner 300 Case study 2 Figure 5, Headspace pressure in vials750 sealed with a grey butyl stopper. There is no evidence of stop- The second case study demonstrates a process devel- 700 per pop up on any shelf or in any location on a 650 750 opment effort aimed at evaluating the container clo- given shelf. 600 700

Shelf1 550 650 Shelf2 LIGHTHOUSE Shelf3 The Science of Pharmaceutical Manufacturing Shelf4 500 600 UpperSpecification (650 Torr) Target (413.7 Torr,8psia) LowerSpecification (350 TorrSh) elf1 450 550 Shelf2 5 Shelf3 Shelf4 400 500 UpperSpecification (650 Torr) Target (413.7 Torr,8psia) LowerSpecification (350 Torr) 350 450 FrontLeft FrontRight Back Left Back Right Corner Corner Corner Corner 300 400

350 FrontLeft FrontRight Back Left Back Right Corner Corner Corner Corner 300 750

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600 Shelf5 550 Shelf6 Shelf7 Shelf5 550 Shelf8 Shelf6 UpperSpecification (650 Torr) 500 Shelf7 Target (413.7 Torr, 8psia) Shelf8 LowerSpecification (350 Torr)UpperSpecification (650 Torr) 500 Target (413.7 Torr, 8psia) 450 LowerSpecification (350 Torr)

450 400 400 Application Note 101 350 LIGHTHOUSE FrontLeft FrontRight Back Left Back Right The Science of Pharmaceutical Manufacturing Corner 350 Corner Corner Corner 300 FrontLeft FrontRight Back Left Back Right Corner Corner Corner Corner 300

Nitrogen Headspace Pressure 750 Product samples using coated stoppers 750 700 The fact that bad seal integrity was not dependent on lo-

700 650 cation in the freeze dryer pointed to an issue with the

650 600 coated stopper closure system and/or an overall process

600 Shelf1 550 Shelf2 issue. Further container closure studies using nonde- Shelf3 Shelf1 550 Shelf4 Shelf2 500 UpperSpecification (650 TorrSh) elf3 structive headspace analysis allowed the manufacturer Target (413.7 Torr,8psia) Shelf4 500 LowerSpecification (350 TorrU) pperSpecification (650 Torr) 450 Target (4to13.7 To optimizerr,8psia) the stoppering process. Closure failures LowerSpecification (350 Torr) 450 400 with the coated stopper were lowered from > 15% of the 400 350 FrontLeft FrontRight Back Left Back Right batch to < 1% with the optimized process. A headspace Corner 350 Corner Corner Corner 300 FrontLeft FrontRight Back Left Back Right Corner Corner Corner Corner inspection machine was implemented for 100% final 300 Figure 6, Headspace pressure in vials sealed product inspection guaranteeing the detection and re- with a teflon coated stopper. There is widespread jection of any residual vials that had lost container clo- evidence of stopper pop up on all shelves and in all locations on any given shelf. sure integrity.

these vials have maintained seal integrity. The Conclusion headspace pressure levels are uniform and match Stopper pop-up resulting in loss of container closure in- the pressure set in the lyophilzation chamber pri- tegrity is not uncommon and impacts the stability, ste- or to lowering the shelves. Figure 6 shows the rility and reconstitution of lyophilized product. Non-de- headspace pressure in vials from the same batch structive headspace analysis is a powerful method for that were stoppered using a teflon coated elasto- monitoring container closure integrity in finished vials mer closure. Over 15% of these vials did not main- of freeze dried product and for building quality into the tain seal integrity after removal from the lyophili- manufacturing operation. Monitoring absolute pres- zation chamber. The gas ingress into these vials sure changes and/or oxygen ingress in the vial head- resulted in headspace pressures from 30 to 300 space serve as leak indicators. Manually loaded systems torr (40 to 400 mbar) above the target level. are valuable tools for small scale studies and investigations, and fully automated systems have been imple-

mented and validated for 100% product inspection in commercial scale applications.

LIGHTHOUSE The Science of Pharmaceutical Manufacturing

6 About Us

LIGHTHOUSE is the leading manufacturer and provider of optical, non-destructive headspace inspection systems for in-line, at-line, and R&D applications specific to the pharmaceutical industry. LIGHTHOUSE developed the non-destructive headspace inspection systems with funding from the Food and Drug Administration. We have over 100 laser based systems installed around the world at some of the world’s leading pharmaceutical, biopharmaceutical and contracting manufacturing companies including: Amgen, Baxter, Bayer, Boehringer Ingelheim, BMS, DSM, Eli Lilly, Genentech, GlaxoSmithKline, Helvoet Pharma, Johnson & Johnson, Merck, Novartis, Patheon, Pfizer, Roche, Se- rum Institute of India, Sankyo, Sanofi-Aventis, West Pharmaceutical Services, and Wyeth.

North America German Local Office LIGHTHOUSE Instruments, LLC Mr. Jens Hoellein 2020 Avon Court Suite 2 Tel: +49 173 634 8290 Charlottesville, VA 22902 [email protected] Tel: +1 434 293 3081 Fax: +1 434 293 7773 Japan Dencom Corporation 1-5-10 Honcho Europe Kawasaki,Kanagawa 210-0001 Technical Sales & Support Center Japan LIGHTHOUSE Instruments B.V. Tel: +81 44 201 1418 Science Park 408 Fax: +81 44 201 1465 1098 XH Amsterdam [email protected] The Netherlands Tel: +31 6 2017 6502 India [email protected] SPINCO BIOTECH Pvt Ltd No. 4, Vaidyaram Street, T. Nagar Head European Sales Office Chennai 60017 India Monkhurst House, Office 1, Sandy Cross Lane Tel: +91 44 2340174 Heathfield, East Sussex TN21 8QR Fax: +91 44 2340761 UK www.spincotech.com Tel: +44 1435 869033 [email protected] [email protected]

LIGHTHOUSE The Science of Pharmaceutical Manufacturing