Unfortunately, a lot of people do not know much about the process of Chasing or smoking opioids (specifically Heroin)- even though it may be their primary route of administration, or even if they've been doing it for years.
To be clear, there are two distinct routes of administration involving the inhalation of heated Heroin:
Smoking &
Chasing.
Smoking Heroin (also known as 'Ack Ack' or 'Fire The Ack Ack Gun' in East Asia) involves filling part of a cigarette with powder Heroin, applying flame to the end of the cigarette and smoking it like a normal cigarette.
Chasing Heroin (also known as 'Chasing The Dragon') involves placing Heroin in the stem of an Opium pipe, or in the middle of a square piece of aluminum foil, adding heat from the bottom and inhaling the vapours through a tube.
Smoking Heroin (or Opium, or Morphine, etc) is very easy, yet it is a very, very inefficient method of using Heroin. The intense heat of the burning Tobacco and the direct flame degrade and destroy most of the Heroin. Only a small amount of Heroin is vaporized and inhaled.
Chasing Heroin is much more efficient compared to smoking; though improper technique and/or what I'll call "the wrong Heroin" can make Chasing just as if not more inefficient as smoking.
The type of Heroin being used and what it is cut with make a
huge difference in the outcome, regardless of route of administration.
Diacetylmorphine Base (Freebase) is the best form of Heroin to use for Chasing or Smoking. It reaches volatilization much better than its salt forms. However, it is still possible to Chase or Smoke Heroin in a salt form (i.e. Diacetylmorphine Hydrochloride), it is just much less efficient.
The cuts being used are very important.
Caffeine, Barbiturates (Barbital, Phenobarbital), Methaqualone, Phenazone, etc facilitate and enhance Heroin volatilization, meaning more Heroin is being vaporized and available to be inhaled into the lungs and thus into the bloodstream.
This is why Heroin #3 is a 1:1 (50/50) ratio of Heroin Base : Caffeine.
Procaine, Lidocaine, Acetaminophen, Ascorbic Acid, etc have the opposite effect, they decrease and inhibit volatilization. Especially Ascorbic Acid. Very little Heroin will reach the bloodstream even if perfect chasing technique were performed on a Heroin sample that contained, for example, Heroin Hcl + Procaine Hcl.
However, cuts like Procaine enhance the subjective physiological effects of the IV rush from Heroin. Ascorbic Acid or Citric Acid is also necessary in parts of Europe to convert non-water soluble Heroin Base into a water soluble salt (Diacetylmorphine Ascorbate or Citrate) so it can be injected.
Here are my main sources, the second link contains a very interesting article about the Chasing and smoking of Heroin in the Netherlands among the Surinamese immigrant community, along with a lot of scientific information related to Heroin cuts, impurities, efficiency of RoA methods, etc.
http://jpet.aspetjournals.org/cgi/content/abstract/154/1/142
And the interesting link:
http://www.drugtext.org/library/books/grund/chasdra3.htm