Trimagnesium dicitrate: Pharmacodynamics, Mechanism and Function,etc

Background

Trimagnesium dicitrate, also kown as magnesium citrate (Figure 1), is made of magnesium carbonate and citric acid. It had a modest solubility even in water (55%) and achieved maximum solubility at simulated mean basal acid secretion without further dissolution at higher acid concentration. It is a chemical with medicinal properties and contains up to 11 percent magnesium. For this reason, it is often used as a health and nutritional supplement. Magnesium is an important source of magnesium because it is easily absorbed by the body. Trimagnesium dicitrate is a low volume and osmotic cathartic agent. The cathartic action works primarily through the high osmolarity of the solution which draws large amounts of fluid into space where is used. Trimagnesium dicitrate is considered by the FDA as an approved inactive ingredient for approved drug products under the specifications of oral administration of a maximum concentration of 237 mg. It is also considered as an active ingredient in over-the-counter products. Trimagnesium dicitrate has the advantage of being of low volume which increases tolerability, and it is inexpensive, costing around $2 for a two bottle prep. Both factors are important concerns to patients. Brand name bowel preparations can cost at least 10 times and up to100 times the price of trimagnesium dicitrate.  [1]

Trimagnesium dicitrate is signiffcantly less expensive than other available bowel preparations and has better tolerability due to low volume. Several studies have shown that MC has great tolerability as high as 100% in a prospective trial by Gu et al. [2] Also, studies have shown that high- and low-volume preparations are equally effective.[1]

Pharmacodynamics

The onset of action can be as early as 30 minutes after administration with a mean onset time of approximately 2 hours and a maximum action of 4 hours. The effect of trimagnesium dicitrate is highly dependent on the individual's hydration status.

Mechanism of action

Trimagnesium dicitrate mainly works through its property of high osmolality which will draw large amounts of fluid into the colonic lumen. There is also a possible stimulation of fluid excretion by cholecystokinin release and activation of muscle peristalsis.

Absorption

Mean plasma concentration of magnesium after administration of oral doses of trimagnesium dicitrate are reported to be of around 0.7 mmol/L and the concentration in saliva rested in 0.28 mmol/L. In reports, it has also been proven that the absorption and bioavailability of magnesium are greater when administered in the form of trimagnesium dicitrate when compared with other forms such as magnesium ocude.[3]

Protein binding

Magnesium of trimagnesium dicitrate), once ionized, is highly bound to plasma proteins and it can represent even 90% of the magnesium found in blood plasma.

Route of elimination

After oral administration of trimagnesium dicitrate, there is a 40% increase in urine excretion of magnesium.[4] Trimagnesium dicitrate is also widely eliminated via the feces because, when present in the bowel, it relaxes the bowel and pulls water into the intestine which increases bowel movement and a significant portion of this agent gets excreted by this via.

Half-life

The study of the half-life of trimagnesium dicitrate is very difficult due to the half-life of the available isotopes for magnesium.[5]

Toxicity

The occurrence of overdose with trimagnesium dicitrate is very unlikely but some of the signs of the presence of overdose are diarrhea or severe stomach pain.

Function

The most common medical use of trimagnesium dicitrate is as a saline laxative. Before any surgery, the patient is provided with trimagnesium dicitrate to facilitate the evacuation of the bowel. This is because it has a tendency to absorb water from tissues, and when injected into the intestine, it can absorb a large amount of water and exit the body. In fact, it can also treat constipation and colon cancer, or diseases related to rectal cancer. In addition, trimagnesium dicitrate is also effective in preventing kidney stones.

References:

[1] AlSamman MA, Leung S, Moustafa A, Abeid M, Baird GL, Shah SA. Adequacy Rate of Magnesium Citrate Bowel Preparation in a Large Retrospective Cohort. R I Med J (2013). 2022;105(2):46-50. Published 2022 Mar 1.

[2] Gu P, Lew D, Oh SJ, et al. Comparing the Real-World Effectiveness of Competing Colonoscopy Preparations: Results of a Prospective Trial. Am J Gastroenterol. 2019;114(2):305-314. doi:10.14309/ajg.0000000000000057.

[3] Walker AF, Marakis G, Christie S, Byng M. Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study. Magnes Res. 2003;16(3):183-191.

[4] Rylander R, Mégevand Y, Lasserre B, Amstutz W, Granbom S. Moderate alcohol consumption and urinary excretion of magnesium and calcium. Scand J Clin Lab Invest. 2001;61(5):401-405. doi:10.1080/003655101316911459.

[5] Jahnen-Dechent W, Ketteler M. Magnesium basics. Clin Kidney J. 2012 Feb;5(Suppl 1):i3-i14. doi: 10.1093/ndtplus/sfr163.

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