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).
How to use Flexeril. Take this medication by mouth with or without food as directed by your doctor, usually 3 times a day. The dosage is based on your medical condition and response to treatment. This medication should only be used short-term (for 3 weeks or less) unless directed by your doctor. Do not increase your dose or use this drug more often or for longer than prescribed.