Fluoride treatment in osteoporosis

Tetraphenylethylene-Substituted Bis(thienyl)imidazole (DTITPE), An Efficient Molecular Sensor for the Detection and Quantification of Fluoride Ions

Fluoride ion plays a pivotal role in a range of biological and chemical applications however excessive exposure can cause severe kidney and gastric problems. A simple and selective molecular sensor, 4,5-di(thien-2-yl)-2-(4-(1,2,2-triphenylvinyl)-phenyl)-1H-imidazole, DTITPE, has been synthesized for the detection of fluoride ions, with detection limits of 1.37 × 10−7 M and 2.67 × 10−13 M, determined by UV-vis. and fluorescence spectroscopy, respectively. The variation in the optical properties of the molecular sensor in the presence of fluoride ions was explained by an intermolecular charge transfer (ICT) process between the bis(thienyl) and tetraphenylethylene (TPE) moieties upon the formation of a N-H---F− hydrogen bond of the imidazole proton. The sensing mechanism exhibited by DTITPE for fluoride ions was confirmed by 1H NMR spectroscopic studies and density functional theory (DFT) calculations. Test strips coated with the molecular sensor can detect fluoride ions in THF, undergoing a color change from white to yellow, which can be observed with the naked eye, showcasing their potential real-world application.

Isatin as a simple, highly selective and sensitive colorimetric sensor for fluoride anion

Herein, we report the fluoride anion sensing properties of a commercially available and inexpensive organic compound, isatin, which is found to be a highly selective and sensitive sensor. In naked-eye experiments, by addition of fluoride anions, isatin shows a dramatic color change from pale yellow to violet at room temperature, while the addition of other anions, i.e. $\mathrm{Cl}^-,$$\mathrm{Br}^-,\mathrm I^-,\mathrm{ClO}_4^-,{\mathrm H}_2\mathrm{PO}_4^-\,\mathrm{and}\,\mathrm{PF}_6^-,$did not induce any colour change. Additionally, recognition and titration studies have also been done through UV/Vis spectroscopy. Isatin displayed a new absorption band at 533 nm after the addition of fluoride anions, which is presumably due to acid-base interaction between isatin and fluoride anions, while other anions did not trigger noticeable spectral changes. The detection limit was observed to be 0.367 ppm. DFT calculations were also performed to further explain the behavior of receptor 1 towards the Fˉ anion. Owing to high sensitivity and selectivity, isatin can be useful in the detection of biologically or environmentally important fluoride anions at very low concentration.

Deterioration of teeth and alveolar bone loss due to chronic environmental high-level fluoride and low calcium exposure

OBJECTIVES

Health risks due to chronic exposure to highly fluoridated groundwater could be underestimated because fluoride might not only influence the teeth in an aesthetic manner but also seems to led to dentoalveolar structure changes. Therefore, we studied the tooth and alveolar bone structures of Dorper sheep chronically exposed to very highly fluoridated and low calcium groundwater in the Kalahari Desert in comparison to controls consuming groundwater with low fluoride and normal calcium levels within the World Health Organization (WHO) recommended range.

MATERIALS AND METHODS

Two flocks of Dorper ewes in Namibia were studied. Chemical analyses of water, blood and urine were performed. Mineralized tissue investigations included radiography, HR-pQCT analyses, histomorphometry, energy-dispersive X-ray spectroscopy and X-ray diffraction-analyses.

RESULTS

Fluoride levels were significantly elevated in water, blood and urine samples in the Kalahari group compared to the low fluoride control samples. In addition to high fluoride, low calcium levels were detected in the Kalahari water. Tooth height and mandibular bone quality were significantly decreased in sheep, exposed to very high levels of fluoride and low levels of calcium in drinking water. Particularly, bone volume and cortical thickness of the mandibular bone were significantly reduced in these sheep.

CONCLUSIONS

The current study suggests that chronic environmental fluoride exposure with levels above the recommended limits in combination with low calcium uptake can cause significant attrition of teeth and a significant impaired mandibular bone quality.

CLINICAL RELEVANCE

In the presence of high fluoride and low calcium-associated dental changes, deterioration of the mandibular bone and a potential alveolar bone loss needs to be considered regardless whether other signs of systemic skeletal fluorosis are observed or not.

Drug-induced diarrhoea

Diarrhoea is a relatively frequent adverse event, accounting for about 7% of all drug adverse effects. More than 700 drugs have been implicated in causing diarrhoea; those most frequently involved are antimicrobials, laxatives, magnesium-containing antacids, lactose- or sorbitol-containing products, nonsteroidal anti-inflammatory drugs, prostaglandins, colchicine, antineoplastics, antiarrhythmic drugs and cholinergic agents. Certain new drugs are likely to induce diarrhoea because of their pharmacodynamic properties; examples include anthraquinone-related agents, alpha-glucosidase inhibitors, lipase inhibitors and cholinesterase inhibitors. Antimicrobials are responsible for 25% of drug-induced diarrhoea. The disease spectrum of antimicrobial-associated diarrhoea ranges from benign diarrhoea to pseudomembranous colitis. Several pathophysiological mechanisms are involved in drug-induced diarrhoea: osmotic diarrhoea, secretory diarrhoea, shortened transit time, exudative diarrhoea and protein-losing enteropathy, and malabsorption or maldigestion of fat and carbohydrates. Often 2 or more mechanisms are present simultaneously. In clinical practice, 2 major types of diarrhoea are seen: acute diarrhoea, which usually appears during the first few days of treatment, and chronic diarrhoea, lasting more than 3 or 4 weeks and which can appear a long time after the start of drug therapy. Both can be severe and poorly tolerated. In a patient presenting with diarrhoea, the medical history is very important, especially the drug history, as it can suggest a diagnosis of drug-induced diarrhoea and thereby avoid multiple diagnostic tests. The clinical examination should cover severity criteria such as fever, rectal emission of blood and mucus, dehydration and bodyweight loss. Establishing a relationship between drug consumption and diarrhoea or colitis can be difficult when the time elapsed between the start of the drug and the onset of symptoms is long, sometimes up to several months or years.

Fluoride pharmacokinetics and changes in lumbar spine and hip bone mineral density

Debate about the use of fluoride for the treatment of vertebral osteoporosis has centered not only on whether fluoride treatment decreases vertebral fractures, but also the interindividual vertebral bone mineral density (BMD) response, the potential for nonvertebral fractures, as well as side effects and tolerability. These effects may be dose dependent and, in this study, we examine the pharmacokinetics of sodium monofluorophosphate (MFP) in osteoporotic patients and relate this to changes in BMD. Plasma fluoride absorption curves were measured from 0 to 6 h after ingestion of MFP at baseline and during long-term dosing in 21 patients with vertebral osteoporosis (T scores < or = 2). BMD was measured at baseline and at 12 months at the lumbar spine (LS), femoral neck (FN), trochanter, and Ward's triangle. We found that fluoride elimination was inversely related to creatinine clearance. LS BMD increased from a median of 0.77 g/cm2 (range 0.69 to 0.99) at baseline to 0.88 g/cm2 (0.75 to 1.13) (p < 0.001) after 12 months. This equates to a median increase of 12% (range -1.2 to 37). Median femoral neck BMD decreased from 0.75 g/cm2 (0.62 to 0.94) at baseline to 0.69 g/cm2 (0.62 to 0.92) (p = 0.13) after 12 months. This equates to a decrease of -2% (-19 to 10). BMD at the other hip sites also decreased slightly. Changes in LS and FN BMD were not significantly related (r = 0.28, p = 0.29). The various pharmacokinetic parameters measured were not related to changes in LS BMD; however, there was an inverse relationship between trough fluoride concentration during long-term dosing and change in FN BMD. Further studies are required to see if this relationship can be used to monitor osteoporotic patients treated with fluoride and prevent significant decreases in FN BMD and possibly fractures at this site.