There’s been a lot of ink and bytes used on this topic but the question persists:
What is better, singe dosed Ampules or Multidose Vials?

It seems every bodybuilder has a different opinion on the subject, but it would seem that one can see a trend if looking at geographical background of the builder. Bodybuilders living in the North America generally prefer Vials, most Europeans don’t really care as long as it’s good gear, and builders living in the UK prefer amps and will only use vials when no other option is present. This is a very general description of the situation and there are definitively exceptions to this (so don’t write me that “Hey, I live in PA and I only use amps!”). The reason for this division is a bit more complicated and it lays in the strengths and weaknesses of each form.

Amps were designed as a single dose container for sterile compounds and their main advantage is the fact you simply dispose of an amp after use. When using an injectable medicine in regular intervals this means that you use one dose while the rest of your stock is unaffected by application of the dose - this means the contents of other amps remain sterile and can be kept at normal storing conditions until expiration date without any problems. And when taking multiple doses at the same time you simply use multiple ampules. Amps also protect the contents better as there are no rubber seals that could potentially contaminate the contents.
Ampules have their problems though - the save weight and cost the glass it is made of is very thin, and ampules can brake easily if improperly transported (without proper protection). When properly transported, ampules can be quite bulk and when transporting a larger quantity they take more space than a comparable volume in vials. And the last weakness, if we can call it that, is the cumbersome use of ampules. Because an amp is made of a single piece of glass it has to broken in order to be opened. This presents a problem for less experienced/clumsier users because amps can crack in the wrong place, can shatter completely, or on some rare occasions small glass particles of glass can actually fall into the contents.
In the time of extensive drug counterfeiting and underground labs amps are regarded as a better alternative because they are harder to make than vials. Cheap ampule machines have changed that too, but if nothing else usage of amps shows higher commitment of the manufacturer.

Most human grade drugs are made in ampule form but there are some exceptions, especially in the US a lot of Human Grade pharmaceuticals still use vials.

Multidose Vials are mainly used for for veterinary use as the doses vary significantly depending on the animal size, and any complications are not considered so serious. They are also used in human medicine, again for easier changes of the dosages and easier usage of vials when the medicine must be applied in close succession. One of the main strengths of a vial is the ease of use. The user simply pops the top off and inserts the needle. No hassle with braking glass what so ever. With improvements in the technical field the contamination issues during manufacture are almost impossible. Furthermore, vials are smaller than amps (when comparing 10ml vial and 1ml amps) and are hence a lot easier to transport.
On the other hand, vials do have flaws. Should a vial brake during transport, the damage is far greater than with amps (if you brake one amps out of 10, you can still use the other 9…). But the biggest problem is, once you open a vial, you cannot store it indefinitely. Because of it’s design, once you pop the top, the rubber is exposed to the elements. Afterwords end every time you draw the vial, you potentially import foreign object into the solution within the vial. This is not really a concern when proper injection protocols are followed (eg. doctors…), but most juicers don’t inject under perfect conditions and sometimes mistakes are made. Imagine for example what would happen if you used a used pin for drawing a water based steroid like winstrol - although the product was completely sterile when the vial was opened the contaminants on the pin would grow in the water solution and in the long run could be a cause of an infection.

The last and also very important difference between vials and amps lies in the manufacturing procedure. While amps require complicated machinery to be closed vials can be made in a home basement where the top is simply crimped on the vial. That is the reason all underground steroids come in multidose vials - they are a lot simpler to make. It is generalized that a company that bothers to invest into ampule machines will also bother to use better raw materials and batter oils, proper working conditions, etc, which in the end means a better and safer product. On the other hand the underground situation these days is such that people will invest into ampule machines and make perfect copies of Sustanon that contain nothing but kitchen oil while others will make a perfect product that comes in a simple vial. There simply is no rule of thumb…

As was said in the beginning, most people have their preference when it comes to amps vs vials. And most people usually have their preference simply because the products they can obtain come in a specific container, or the product that they had the best success with came in that specific container. However new juicers should consider the strengths and weaknesses named above and decide what is more important for them, hopefully this article will help them decide.