Vials – plastic versus glass

However, looking at the total costs from purchase to the filled product you will in most cases find that plastic vials are the most economical solution.

The reason is that glass vials require pre-washing by sterile water and drying before filling. Plastic vials produced and packed under correct hygienic conditions do not require this operation.

The Survey

Promens Medical Packaging A/S produces vials from the environmental friendly materials Polyethylene and Polypropylene.

During recent years plastic vials have gained ground at the expense of glass vials, primarily due to important properties like impact strength, low weight, and no pre-operations like washing.

None the less approx. 95% of all vials on the market are still made from glass.
One of the main reasons is that many drug types are from an earlier date and were tested and registered in glass vials which were the only choice then. Another reason is when choosing the primary packaging the total costs are not taken into account - focus is on the purchase price of the vial.

Together with a Spanish producer of injectable solutions Promens Medical Packaging A/S has made a survey to compare the actual total costs for filling in plastic and glass. The results from the survey, which should not be considered scientific, are described below. The details may vary from one producer to another, however, it can be stated that the filling of glass vials initiates costs that will not occur when filling plastic vials.

The assumptions of the survey can be changed to fit different production and cost conditions. The advantages of plastic vials are fully obtained if you only fill plastic vials and abolish equipment for pre-wash and drying.

Total Cost Overview - glass versus plastic

The basis is a production unit filling and sterilising injectables in vials from arrival of the empty vial until the filled vial is packed and stored.

The prices for vials are as follows:

Material Units ml Euro/unit Total cost

The purchase price of PP (Polypropylene) vials is 21% higher than glass vials.

A sketch of the prprome

oduction run for glass and plastic is shown below. As shown the glass vial must pass through a washing area and a dry sterilisation area, which is not the case for plastic vials.

The filling capacity is:

Filling capacity for glass per week:

• Per hour = 4,000 units/hour
• 6 hours/day = 24,000 units/day
• 4 days/week = 96,000 units/week

Filling capacity for PP per week:

• Per hour = 4,000 units/hour
• 7 hours/day = 28,000 units/hour
• 5 days/week = 140,000 units/week

The reason why you can fill more Polypropylene vials per week than glass vials is that the filling can start directly when starting up Monday morning and continue until Friday afternoon.

Glass vials have to pass through the wash and dry sterilisation area before being ready for filling. This takes half the Monday and the production has to be stopped by Friday noon, as you cannot store washed vials during the weekend.

The calculations below do not include costs in connection with the filling itself since those are the same for glass and plastic.

Washing Area (4,000 pcs/hour)

For glass vials the following costs related to the washing area are calculated:

Comparison:

50 ml glass vials

96,000 units/week * 0.105 €/pcs
= 10,080.00 €
+ 5,349.77 € (washing+dry sterilisation)
= 15,429.77 € / 96.000 pcs
= 0.16 €/pcs

50 ml PP vials

140,000 units/week * 0.133 €/pcs
= 18,620,00 € / 140,000 pcs
= 0.13 €/pcs

Conclusion

Considering all costs related to the filling of vials there is no economical difference between glass vials and PP vials. Above calculation even shows a difference to the advantage of PP of approx 20% if the producer only invests in one line for filling PP vials.

No matter which assumptions are used (purchase prices for vials and equipment, rules of depreciation, etc.) filling of glass vials will require some additional costs compared to PP vials.

Filling of both glass vials and PP vials on one line will narrow down the difference.

An additional benefit for PP vials is the possibility to change vial size without planning in advance. As glass vials have to be washed and dried immediately before filling a longer planning horizon is necessary, i.e. the washing and sterilisation time.

Such knowledge is important for decision makers as the price is often crucial and above information includes the total costs and consequently the competitive strength of the product.

Summing up the benefits of PP vials:

Promens Medical Packaging A/S has a large program of PP vials in sizes from 2 ml to 1000 ml. All with the same neck measure as glass vials (ISO standard), allowing the use of same rubber stoppers and alu caps.

PP vials can be autoclaved at 121^oC for 20 minutes and need no pre-washing.
The vials are produced under hygienic conditions and packed in clean room class C. They are delivered in bricks with two layers of plastic foil, packed in cartons, lined with one plastic bag which is closed by a binder, i.e. prepared for entering the filling room through the locker system.