frameshift mutation / frame-shift mutation; frameshift. A frameshift mutation is a genetic mutation caused by a deletion or insertion in a DNA sequence that shifts the way the sequence is read. A DNA sequence is a chain of many smaller molecules called nucleotides.
As for Flexeril (cyclobenzaprine) is is not a controlled substance under US, Canadian, or international law. Some drugs used as muscle relaxants ARE controlled substances like Valium and many US states and countries have listed Soma (carisoprodol) as a controlled substance (or prohibited it).
To help release very tight muscle spasms, some people take Flexeril. Approved by the FDA in 1977, this drug is but one type of skeletal muscle relaxer. Below is a fact sheet about Flexeril, including side effects, generic information, dosage and storage information, and more.