Niacin formulations

Several different niacin formulations are available niacin immediate-release (IR), niacin sustained-release (SR), and niacin extended-release (ER).28,29 These formulations differ in terms of dissolution and absorption rates, metabolism, efficacy, and side effects. Limitations of niacin IR and SR are flushing and hepatotoxicity, respectively. These differences appear related to the dissolution and absorption rates of niacin formulations and its subsequent metabolism. Niacin IR is available by prescription (Niacor ) as well as a dietary supplement which is not regulated by the FDA.28 Currently, there are no FDA-approved niacin SR products, thus, all SR products are available only as dietary supplements. 

Pieper JA (2003) Overview of niacin formulations differences in pharmacokinetics, efficacy, and safety. Am J Health Syst Pharm 60(Suppl 2) S9-14. Knodel LC, Talbert RL (1987) Adverse effects of hypolipidaemic drugs. Med Toxicol 2 10-32. 

I want you to know that I don t own stock in the Endurance Products Company and that I don t get a cent for recommending Endur-acin. I do so because I believe it is the best niacin formulation in the world, and I want my readers to have the best. 

Water-soluble vitamins in formulations have been determined by use of ion-pair chromatography. The vitamins include several B vitamins as well as niacin, folic acid, and ascorbic acid (565). Vitamins D and Da were rapidly separated on reverse phase columns (247) as are vitamins A, D, and E in multivitamin tablets (564). Addition of silver ions to the mobile phase has been shown to increase the flexibility inherent in RPC by complexing with the unsaturated bonds and thereby decreasing the retention factor. This effect is also observed with other unsaturated drug molecules including steroids (247). Vitamin A and related compounds have... 

The beneficial and adverse effects of nicotinic acid (niacin) have been reviewed (12). Standard nicotinic acid from an immediate-release formulation is metabolized primarily by conjugation, which results in a high frequency of flushing. Long-acting nicotinic acid is metabolized through the nicotinamide pathway, which results in less flushing but increases the risk of hepatotoxicity. Modified-release nicotinic acid, on the other hand, has a more balanced metabolism and causes fewer of both types of adverse effects. 

Niacin and acipimox should be relatively safe to use in the absence of varices, gastritis, coagulopathy, thrombocytopenia or a history of decompensation. Both can cause pruritus, which is common in cholestatic liver disease. The extended release formulation of niacin (Niaspan Prolonged Release) may cause hepatitis and LFTs should be monitored. 

Acipimox is only partly metabolised and should be safe in this patient. Niacin undergoes extensive first-pass metabolism, which would be reduced due to the decrease in liver blood flow caused by the patient s cirrhosis. Niacin (nicotinic acid) has been reported to cause transient elevations in transaminases at high doses. Hepatitis and fibrosis have also been reported with niacin, usually with the SR once-daily formulation. 

The immediate-release formulation of phytosterols is made by Endurance Products Company, based outside of Portland, Oregon. Its Web site is www.endur.com. This is the same company that makes the best formulation of my favorite method of cholesterol control, niacin. Place orders outside the United States at www. endur.com click on Customer Service page. International Orders. Take two 450 mg tablets at the start of two major meals daily to block the absorption of cholesterol in the foods you eat, inhibit the recycling of bile made of cholesterol, and achieve a cholesterol reduction in your bloodstream of up to 10 percent. 

A prescription-only sustained-release niacin, NiaSpan, has been widely promoted to doctors, but the formulation, frankly, is inferior to that of Endur-acin. Readers of mine whose doctors convinced them to switch from Endur-acin to NiaSpan have written to me complaining of flushing and gastric disturbances. 

Uses. Inactive dried yeasts are used as ingredients in many formulated foods baby foods, soups, gravies, and meat extenders as carriers of spice and smoke flavors and in baked goods. Yeasts used in the health food industry are generally fortified with minerals and contain higher concentrations of the B vitamins, especially thiamin, riboflavin, and niacin (see VlTAMlNs). 

Allergic skin reactions (17) and other adverse effects, including dermatological problems and neurological symptoms, have been described in individuals using such formulations. Heavy chronic consumption of kava-kava can lead to a pellagroid dermopathy that appears to be unrelated to niacin deficiency (18). 

Additionally, sodium bicarbonate is used in solutions as a buffering agent for erythromycin, lidocaine, local anesthetic solutions, and total parenteral nutrition (TPN) solutions. In some parenteral formulations, e.g., niacin, sodium bicarbonate is used to produce a sodium salt of the active ingredient that has enhanced solubility. Sodium bicarbonate has also been used as a freeze-drying stabilizer and in toothpastes. 

Many vitamins are quite stable under normal processing conditions and present little or no stability problems in finished pharmaceutical products. These include biotin, niacin, niacinamide, pyridoxine, riboflavin, and a-tocopheryl acetate. Others that can present problems are ascorbic acid, calciferol, calcium pantothenate, cyanocobalamin, fola-cin, and retinyl esters. Overages above label claim are customarily added to vitamin formulations as a means of maintaining the claimed level of each vitamin for the expected shelf life of the products. The percent overage for a particular vitamin such as L-ascorbic acid will vary... 

Like niacin, niacinamide is indicated in the treatment and prevention of deficiency statc.s. Unlike niacin, niacinamide has no vasodilatory effect, which may be of therapeutic importance for compliance rea.sons. Niacinamide has no effect on uiglycerides and lipoproteins. This product is formulated with pota.ssium iodide and u.sed as an iodine supplement. 

Vitamin requirements for ESKD patients receiving dialysis differ from those of a healthy person because of dietary modifications, kidney dysfunction, and dialysis therapy. The plasma concentrations of vitamins A and E are elevated in ESKD, while those of the water-soluble vitamins (81,82,8g, 812, niacin, pantothenic acid, folic acid, biotin, and vitamin C) tend to be low in this population, in large part due to the fact that many are dialyzable. The goal for vitamin supplementation in this population should be to prevent subclinical and frank deficiency and to avoid pathology from overdosage. Special vitamin supplements have been formulated for the dialysis population, which primarily include 8 vitamins with C and folic acid. 

Niacinamide was formulated to be a form of niacin that does not cause flushing of the skin. However, it has little effect on lowering cholesterol. 

Kashjfap ML, McGovern ME, Berra K, Guyton JR, Kwiterovich PO, Harper WL, Toth PD, Favrot LK, Kerzner B, Nash SD, Bays HE, Simmons PD. Long-term safety and efficacy of a once-daily niacin/lovastatin formulation for patients witii cfysl idaemia. Am J Cardiol (2002) 89, 672-8. 

Sample preparation should liberate the vitamin from the matrix, e.g., tissue or plasma, where it often occurs chemically or physically bound. Many specific transport binding proteins are known, e.g., for retinol. Chemical bonding can include the incorporation of a vitamin into coenzymes, e.g., niacin and pantothenate in NAD and coenzyme A, respectively. Liberating vitamins from industrial product forms (formulations) is also an important issue. Here, vitamins are often encapsulated in small beadlets, e.g., from gelatin, which protects them from oxygen and makes them easier to add during processing. 

Serious hepatic toxicity can occur with niacin, but it is almost entirely associated with use of SR formulations. In a randomized clinical trial, 12 out of 23 patients (52%) taking SR niacin developed hepatotoxicity while none of 23 patients taking IR niacin did (McKenney et al. 1994). Therefore, IR or ER... 

Drag formulations The development of an extended-release formulation of nicotinic acid, named ER niacin has been an... 

---