A new drug called Vyvanse (Lisdexamfetamine) has entered the world of ADHD stimulant medications relatively recently. Vyvanse was originally marketed as an ADHD treatment for children, but has recently been approved by the FDA for adult and adolescent use this past April. A cousin of the popular ADHD medications Dexedrine and Adderall, Vyvanse includes some key modifications from these other meds. Some reports (unverified) suggest that Shire Pharmaceuticals, the makers of Vyvanse, are pushing this new drug aggressively over Adderall XR. While Adderall is a chemical mixture of amphetamine salts including enantiomers, Vyvanse only contains the one enantiomer thought to be more "active".
A quick side note on enantiomers: Entantiomers are essentially "mirror images" of the same chemical compound, like a person's left and right hand. The body, like most objects in nature, react differently to and often heavily prefer one "mirror image" over the other. Certain ADHD medications such as Focalin, have already employed this technique. Focalin is an isolation of only one of the two mirror images that make up Ritalin, another popular ADHD medication. In addition, the ADHD medication Dexedrine also employs this mirror-image selectivity regarding its composition.
The second major difference between Vyvanse and other amphetamines such as Adderall, is that Vyvanse is listed as a " pro-drug". A pro-drug is essentially an inactive form of a drug, which, when broken down or metabolized by the body, releases the active drug form. Vyvanse contains an amphetamine which is chemically linked to an amino acid (a building block component of proteins) called lysine. In the body, this chemical linkage is severed by special enzymes which separate Vyvanse into the amphetamine drug and leftover lysine fragment (which is easily disposed of, since lysine is a naturally occurring amino acid in its own right).
***Blogger's note: I will be citing a number of studies previously conducted on the drug lisdexamfetamine. Keep in mind that this is a relatively new drug, so it does not have the history of a drug such as methylphenidate. Nevertheless, I have tried to keep a good balance of sample studies on the drug to report on. The list of studies mentioned and referred to here, are by no means exclusive! While not all of the studies used the Vyvanse brand of the drug, I will be using the terms "Vyvanse" and lisdexamfetamine interchangeably throughout the post.
***Additionally, please do not take this information as official medical advice. I am simply trying to highlight some of the pluses and minuses of the drug and arm you with information so you can better consult with your physician on the merits of this drug.This chemically-modified form carries several apparent advantages for Vyvanse:
Additionally, Vyvanse also carries some other distinctive advantages:
This blog, of course, is not designed to sound like some sort of promotional "infomercial" touting all of the benefits of Vyvanse while leaving out potential risk factors. To keep things balanced, I have included some of the negative attributes of this particular stimulant medication as well:
Medication Doses Available:
30 mg, 50 mg and 70 mg were the original strengths available, but recently 20 mg, 40 mg and 60 mg doses have been added. The amount of amphetamine delivered in Vyvanse compared to Dexedrine approximately a 5:2 ratio. For example, 50 mg of Vyvanse corresponds roughly to 20 mg Dexedrine, 25 mg Vyvanse to 10 mg Dexedrine, etc. 30 mg is often a starting point for children, but doses can be carefully ramped up under the guidance of a physician. In general, it appears that many of the negative side effects can be kept at bay by staying under the 70 mg amount.
A quick side note: For another good source of information on medication dosages, I recommend the blog of Dr. Charles Parker. His blog can be found here. Additionally, he talks about a paradox called the therapeutic window. This is interesting to note, because sometimes ADHD medications which are prescribed at too high of a dosage actually result in ADHD symptoms to re-emerge and give the false impression of underdosage. You can check out this blog article here.
With regards to upper limits and safety measures, based on the studies mentioned above, negative side effects tend to increase around the 70 mg mark. Nevertheless, studies have been done at levels up to 130-150 mg. It is interesting to note that once this high range was reached, the amphetamine concentration in the blood began to taper off. This is good news with regards to the potential for overdose and buildup of toxic levels (note the relatively efficient rate of clearance of Vyvanse mentioned earlier in this post).
As a final word of caution: Remember that Vyvanse is essentially a new delivery method of amphetamines. I have highlighted some of the positives such as lower addiction potential and prolonged modes of action. However, keep in mind that there is often a strong "publication" bias, in that studies which find a drug to be ineffective or even counter-effective are often not reported or published. I therefore urge you to take some of these "glowing" reports on the drug with a grain of salt. Nevertheless, I remain at least cautiously optimistic with regards to the potential merits of lisdexamfetamine for treating ADHD and related disorders. We will be investigating other ADHD medication options shortly in future blog posts.