Not to be confused with Metolazone

Metolazone

Metolazone is a thiazide-like diuretic marketed under the brand names Zytanix from Zydus Cadila, Zaroxolyn, and Mykrox. It is primarily used to treat congestive heart failure and high blood pressure. Metolazone indirectly decreases the amount of water reabsorbed into the bloodstream by the kidney,...

, a diuretic.

Metaxalone (marketed by King Pharmaceuticals

King Pharmaceuticals

King Pharmaceuticals , was the world's 39th largest pharmaceutical company, based in Bristol, Tennessee. However, on October 12, 2010, King was acquired by Pfizer for $14.25 per share. King produced a wide range of pharmaceuticals, including Altace for heart attack prevention, Levoxyl for...

 under the brand name Skelaxin) is a muscle relaxant

Muscle relaxant

A muscle relaxant is a drug which affects skeletal muscle function and decreases the muscle tone. It may be used to alleviate symptoms such as muscle spasms, pain, and hyperreflexia. The term "muscle relaxant" is used to refer to two major therapeutic groups: neuromuscular blockers and spasmolytics...

 used to relax muscles and relieve pain caused by strains, sprains, and other musculoskeletal conditions. Its exact mechanism of action is not known, but it may be due to general central nervous system

Central nervous system

The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...

 depression

Depressant

A depressant, or central depressant, is a drug or endogenous compound that depresses the function or activity of a specific part of the brain...

. It is considered to be a moderately strong muscle relaxant, with relatively low incidence of side effects. Skelaxin comes in an 800 mg scored tablet. It previously came in both 400 mg and 800 mg tablets. The 400 mg tablet has been discontinued. Possible side effects include nausea, vomiting, drowsiness and CNS side effects such as dizziness, headache, and irritability.

Metaxalone exhibits increased bioavailability

Bioavailability

In pharmacology, bioavailability is a subcategory of absorption and is used to describe the fraction of an administered dose of unchanged drug that reaches the systemic circulation, one of the principal pharmacokinetic properties of drugs. By definition, when a medication is administered...

when taken with food. Specifically, in one study, compared to fasted conditions, the presence of food at the time of drug administration increased C(max) by 177.5% and increased AUC(last) by 123.5% and AUC(inf) by 115.4%. Thus, based on the information in the labeling, patients receiving metaxalone therapy are directed to take metaxalone with food, and are informed that taking metaxalone with food results in an increase in the oral bioavailability of metaxalone compared to taking metaxalone without food.

Metabolism of metaxalone involves the liver cytochrome P450 system. Based on the information in the labeling, patients receiving metaxalone therapy and physicians prescribing metaxalone are directed to take precaution when co-administering with other medications involving the P450 system.

Because of potential for side effects, this drug is on the list for High Risk Medications in the elderly. (See NCQA’s HEDIS Measure: Use of High Risk Medications in the Elderly, http://www.ncqa.org/Portals/0/Newsroom/SOHC/Drugs_Avoided_Elderly.pdf).

External links

• Skelaxin (manufacturer's website)