Posted by 3 Beer Effect on May 14, 2002, at 1:11:22
In reply to Adderall (vs.) Dexedrine: DOSE RATIOS/Proportions?, posted by Janice157 on May 12, 2002, at 22:30:09
I've been wondering this myself, but I've searched through tons of literature & books & never found an adequate answer.
I have found that every psychiatry textbook says Ritalin (methylphenidate) is half as potent as Dexedrine (dextroamphetamine). So, 20 mg of Ritalin= 10 mg of Dexedrine. For purely mental stimulation, I personally don't think this is true. It seems (to me) they are about equipotent with Ritalin having a slight advantage & being much better at 'focus' (but doesn't last nearly as long).
Dexedrine/Dextrostat/Dextroamphetamine Sulfate are purely the d-isomer of amphetamine. The time to peak blood level is usually about 2 hours, with an effective duration of action of 4-5 hours and an elimination 1/2 life of 10.25 hours.
Dexedrine (GlaxoSmithKline pharms) is probably the most effective of the 3 but unfortunately, is only available in 5 mg tablets. Dextrostat (made by Shire, the makers of Adderall) & the generic Dextroamphetamine (Barr) are available in 5 & 10 mg tablets. Personally, I take Dextrostat since it is "sort of" a 'name brand' & as such is the only 'name brand' available in 10 mg tablets.
Adderall IR, XR, or its generic are made up of 1/4 each of the following:
D-amphetamine Sulfate USP (Dexedrine); Amphetamine Sulfate USP (d,l racemic amphetamine/Benzedrine);
D,L Amphetamine aspartate monohydrate.
"Adderall contains d-amphetamine & l-amphetamine salts in the 3:1 ratio."
The peak blood level for Adderall IR is achieved around 3 hours (XR 7 hrs) and they last about 6 hours (XR 12 hours).
Because of the 4 different amphetamines that make up Adderall, it is very tough to make a direct comparison to Dexedrine. The l-isomer of amphetamine that makes up some of Adderall stimulates in a different way (peripheral) than the d-isomer (CNS). The d-isomer stimulates the brain without much stimulation of the body, while the l-isomer increases breathing, heart rate etc. So, although the blood level of d-amphetamine is lower with Adderall than with an equivalent dose of Dexedrine, it feels just as stimulatory because your breathing & heart rate increase.
Although Adderall seems like some new high-tech ADD drug, it was originally just an old discontinued amphetamine diet pill called Obetrol that Shire pharmaceuticals bought the patent rights to, renamed it ADDerall, put it through FDA ADD trials & the rest is history. Because of its original intent (amphetamine diet pill), that probably explains the presence of the l-isomer which is better at weight loss/speeding up metabolism and has a longer duration of action. Adderall does work quite well though for ADD, & unlike Dexedrine/Dextrostat is available in a wide variety of doses.
Ironically, Adderall is widely perceived to be "softer" or less likely to be abused than Dexedrine even though one of the ingredients of Adderall is d,l racemic amphetamine sulfate, also known as 'Benzedrine', one of the infamous forms of "speed" widely abused both intranasally, & intraveneously during the late 1960s. Dexedrine probably suffers from this (incorrect) perception simply because it was around in the late 1960s & was subject to abuse but not as much as Benzedrine or Desoxyn, Methedrine (methamphetamine hcl).
Personally, I think Dexedrine 'feels' more like Ritalin in its effects- probably better than Adderall at mental stimulation/focus & with less anxiety than Adderall, but Adderall "wakes you up" better & lasts longer.
Here is more relevant info I have found from an excellent book I found printed back in the days when Dexedrine was much more widely prescribed- Remington Pharmaceutical Sciences (1970):
"Dextroamphetamine with greater CNS action & less peripheral action is generally preferred to amphetamine."
"As a central stimulant, the d-isomer is approximately twice as potent (on a weight basis) as the racemic mixture (d,l amphetamine sulfate) and 3 to 4 times as potent as the l-isomer in elicitation of CNS excitatory effects."
"The l-isomer is approximately twice as potent as the d-isomer in its cardiovascular actions."
"The actions & uses of dextroamphetamine are very similar to those of racemic amphetamine (sulfate) but the peripheral actions are considerably weaker."
poster:3 Beer Effect