Journal of Medical Nutrition and Nutraceuticals

: 2014  |  Volume : 3  |  Issue : 1  |  Page : 1--2

Way to bone health may be just under the tongue! Sublingual vitamin D

Ranabir Salam1, Manash P Baruah2, Bharti Kalra3,  
1 Department of Medicine, Regional Institute of Medical Sciences, Imphal, Manipur, India
2 Consultant Endocrinologist, Excel Center, Guwahati, Assam, India
3 Bharti Hospital and Karnal, Haryana, India

Correspondence Address:
Ranabir Salam
Department of Medicine, Regional Institute of Medical Sciences, Imphal, Manipur - 795 004

How to cite this article:
Salam R, Baruah MP, Kalra B. Way to bone health may be just under the tongue! Sublingual vitamin D.J Med Nutr Nutraceut 2014;3:1-2

How to cite this URL:
Salam R, Baruah MP, Kalra B. Way to bone health may be just under the tongue! Sublingual vitamin D. J Med Nutr Nutraceut [serial online] 2014 [cited 2023 Sep 29 ];3:1-2
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Full Text

The first evidence of drug absorption via the buccal mucosa was noted over 100 years ago. Subsequently, in 1879, sublingual administration of nitroglycerin was reported to successfully alleviate the symptoms of classic angina pectoris. Since then, oral mucosal drug delivery has drawn more and more attention because of its potential advantages over other routes of delivery. The concept of an aerosol originated as early as 1790, when self-pressurized carbonated beverages were introduced in France. Oral spray releases medicament rapidly in the form of micro-sized droplets in intraoral cavity to be absorbed by buccal mucosa, a direct and rapid dispersion of a solution of the active agent over as large a portion as possible of the oral mucosa, which absorbs the active agent.

For oral delivery through the gastrointestinal (GI) tract, the drug undergoes a rather hostile environment before absorption. This includes a drastic change in GI pH (from pH 1-2 in the stomach to 7-7.4 in the distal intestine), unpredictable GI transit, the presence of numerous digestive enzymes, and intestinal flora. In contrast to this harsh environment of GI tract, the oral cavity offers relatively consistent and friendly physiological conditions for drug delivery which are maintained by the continuous secretion of saliva. Most studies of buccal absorption indicate that the predominant mechanism is passive diffusion across lipid membranes via either the paracellular or transcellular pathways.

In sublingual administration, drug is deposited on the tongue and drug reaches directly into the blood stream through ventral surface of the tongue and floor of the mouth. The drug solutes are rapidly absorbed into the reticulated vein which lies underneath oral mucosa; and transported through the facial veins, internal jugular vein, and brachiocephalic vein and then drained into systemic circulation. The sublingual route usually produces a faster onset of action than orally ingested tablets and the portion absorbed through sublingual blood vessels bypasses the hepatic first-pass metabolic processes. The main mechanism for absorption of the drug into oral mucosa is via passive diffusion into the lipoidal membrane. The absorption of the drug through sublingual route is three to ten times greater than oral route and is only surpassed by hypodermic injection. For these formulations, the small volume of saliva is usually sufficient to result in tablet disintegration in the oral cavity.

Vitamin D is a secosteroid hormone that is made in the skin from 7-dehydrocholesterol upon exposure of the skin to ultraviolet B (UVB) radiation. This hormone is important for maintaining the normal bone health and deficiency causes rickets in children and osteomalacia in adults. Hypovitaminosis D also causes low bone mineral density. Several countries across the globe have reported a high prevalence of Vitamin D deficiency to the tune of almost 90%. Many countries have started vitamin D fortification foods or recommend the use of vitamin D supplements. However, several studies have reported differences in the bioavailability of vitamin D supplements in some populations. Decreased bioavailability may be due to altered absorption of vitamin D from the small intestine or it may be due to altered metabolism of vitamin D in the body. Intestinal malabsorption disorders may cause a decrease in vitamin D absorption due to a decreased ability to absorb lipids.

While sublingual absorption takes vitamin D directly into the systemic circulation like vitamin D from skin; orally ingested vitamin D, in contrast, is absorbed into the portal circulation from the intestines, which takes it to the liver first before entering into the systemic circulation. The absorption of vitamin D from the GI tract is incomplete, and also there is local intestinal degradation and hepatic metabolism. Oral ingestion is not physiological and sublingual absorption is physiological. This becomes even more important in people who have problems with digestion, take medications that can interfere with intestinal absorption of vitamin D, and people with stomach bypass surgery including those with Lap-band procedures.

For medical fraternity, the new millennium has started with wake up calls to eliminate vitamin D deficiency which is surprisingly much more common than anticipated. The parentral route has, over the years, given way to oral administration. But sublingual route is arguably an acceptable way to eliminate vitamin D deficiency. However, we will need more evidence from future studies to see whether it is the superior way to administer vitamin D compared to the conventional ones and justify the notion: Way to bone health may be just under the tongue!