Actions of Niacin in details
Niacin binds to Nicotinate D-ribonucleotide phyrophsopate phosphoribosyltransferase, Niacin phosphoribosyltransferase, Nicotinate N-methyltransferase and the Niacin receptor. Niacin is the precursor to nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are vital cofactors for dozens of enzymes. The mechanism by which Niacin exerts its lipid lowering effects is not entirely understood, but may involve several actions, including a decrease in esterification of hepatic triglycerides. Niacin treatment also decreases the serum levels of apolipoprotein B-100 (apo B), the major protein component of the VLDL (very low-density lipoprotein) and LDL fractions.
How should I take Niacin?
Use exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.
Niacin is sometimes taken at bedtime with a low-fat snack. Follow your doctor's instructions.
Niacin can cause certain side effects, such as flushing (warmth, itching, redness, or tingly feeling under your skin). These effects can be made worse if you drink alcohol or hot beverages shortly after you take Niacin. These effects should disappear over time as you keep taking the medication.
Take Niacin with a full glass of cold or cool water. Taking the medication with a hot drink may increase your risk of side effects such as flushing.
Do not crush, chew, break, or open an extended-release tablet or capsule. Swallow it whole. Breaking or opening the pill may cause too much of the drug to be released at one time.
Niacin extended-release tablets and capsules contain higher strengths of the medicine than the regular Niacin tablets. Take only the dose that is correct for the type of Niacin tablet or capsule you are using.
Niacin can cause you to have unusual results with certain medical tests (urine tests). Tell any doctor who treats you that you are using Niacin.
If you stop taking Niacin for any length of time, talk with your doctor before starting the medication again. You may need to restart the medication at a lower dose.
While using Niacin, you may need blood tests at your doctor's office. Your kidney or liver function may also need to be checked. Visit your doctor regularly.
Niacin is only part of a complete program of treatment that may also include diet, exercise, weight control, and other medications. Follow your diet, medication, and exercise routines very closely.
Store at room temperature away from moisture and heat.
Niacin administration
Administer with food. To attenuate flushing symptoms, may premedicate with aspirin 30 minutes before dose; avoid ingestion of alcohol, hot or spicy foods/liquids concurrently with Niacin. May also use other nonsteroidal anti-inflammatory drugs to prevent flushing according to the manufacturer.
Niaspan: Administer at bedtime after a low-fat snack. Two of the 500 mg and one of the 1,000 mg tablet strengths are interchangeable, but three of the 500 mg and two of the 750 mg tablet strengths are not interchangeable. When switching from IR tablet, initiate Niaspan with the recommended titration schedule. If therapy is interrupted for an extended period, dose should be retitrated.
Long-acting forms should not be crushed, broken, or chewed. Slo-Niacin may be broken along the score line. Do not substitute long-acting forms for immediate release ones.
Bariatric surgery: Capsule and tablet, extended release: Some institutions may have specific protocols that conflict with these recommendations; refer to institutional protocols as appropriate. ER formulations should be swallowed whole. Do not chew or crush. If safety and efficacy of Niacin can be effectively monitored, no change in formulation or administration is required after bariatric surgery. Bariatric vitamin supplementation is recommended on a lifelong basis after surgery; consider integration of daily Niacin regimen into the bariatric vitamin regimen.
Niacin pharmacology
Mechanism of Action
The mechanism by which Niacin alters lipid profiles has not been well defined. It may involve several actions including partial inhibition of release of free fatty acids from adipose tissue, and increased lipoprotein lipase activity, which may increase the rate of chylomicron triglyceride removal from plasma. Niacin decreases the rate of hepatic synthesis of VLDL and LDL, and does not appear to affect fecal excretion of fats, sterols, or bile acids.
Pharmacokinetics
Absorption
Due to extensive and saturable first-pass metabolism, Niacin concentrations in the general circulation are dose dependent and highly variable. Time to reach the maximum Niacin plasma concentrations was about 5 hours following Niacin extended-release tablets. To reduce the risk of gastrointestinal (GI) upset, administration of Niacin extended-release tablets with a low-fat meal or snack is recommended.
Single-dose bioavailability studies have demonstrated that the 500 mg and 1000 mg tablet strengths are dosage form equivalent but the 500 mg and 750 mg tablet strengths are not dosage form equivalent.
Metabolism
The pharmacokinetic profile of Niacin is complicated due to extensive first-pass metabolism that is dose-rate specific and, at the doses used to treat dyslipidemia, saturable. In humans, one pathway is through a simple conjugation step with glycine to form nicotinuric acid (NUA). NUA is then excreted in the urine, although there may be a small amount of reversible metabolism back to Niacin. The other pathway results in the formation of nicotinamide adenine dinucleotide (NAD). It is unclear whether nicotinamide is formed as a precursor to, or following the synthesis of, NAD. Nicotinamide is further metabolized to at least N-methylnicotinamide (MNA) and nicotinamide-N-oxide (NNO). MNA is further metabolized to two other compounds, N-methyl-2-pyridone-5-carboxamide (2PY) and N-methyl-4-pyridone-5-carboxamide (4PY). The formation of 2PY appears to predominate over 4PY in humans. At the doses used to treat hyperlipidemia, these metabolic pathways are saturable, which explains the nonlinear relationship between Niacin dose and plasma concentrations following multiple-dose Niacin extended-release tablet administration.
Nicotinamide does not have hypolipidemic activity; the activity of the other metabolites is unknown.
Elimination
Following single and multiple doses, approximately 60 to 76% of the Niacin dose administered as Niacin extended-release tablets was recovered in urine as Niacin and metabolites; up to 12% was recovered as unchanged Niacin after multiple dosing. The ratio of metabolites recovered in the urine was dependent on the dose administered.
Pediatric Use
No pharmacokinetic studies have been performed in this population (≤ 16 years).
Geriatric Use
No pharmacokinetic studies have been performed in this population (> 65 years).
Renal Impairment
No pharmacokinetic studies have been performed in this population. Niacin extended-release tablets should be used with caution in patients with renal disease.
Hepatic Impairment
No pharmacokinetic studies have been performed in this population. Active liver disease, unexplained transaminase elevations and significant or unexplained hepatic dysfunction are contraindications to the use of Niacin extended-release tablets.
Gender
Steady-state plasma concentrations of Niacin and metabolites after administration of Niacin extended-release tablets are generally higher in women than in men, with the magnitude of the difference varying with dose and metabolite. This gender difference observed in plasma levels of Niacin and its metabolites may be due to gender-specific differences in metabolic rate or volume of distribution. Recovery of Niacin and metabolites in urine, however, is generally similar for men and women, indicating that absorption is similar for both genders.
Drug Interactions
Fluvastatin
Niacin did not affect fluvastatin pharmacokinetics.
Lovastatin
When Niacin extended-release tablets 2000 mg and lovastatin 40 mg were co-administered, Niacin extended-release tablets increased lovastatin Cmax and AUC by 2% and 14%, respectively, and decreased lovastatin acid Cmax and AUC by 22% and 2%, respectively. Lovastatin reduced Niacin extended-release tablet bioavailability by 2 to 3%.
Simvastatin
When Niacin extended-release tablets 2000 mg and simvastatin 40 mg were co-administered, Niacin extended-release tablets increased simvastatin Cmax and AUC by 1% and 9%, respectively, and simvastatin acid Cmax and AUC by 2% and 18%, respectively. Simvastatin reduced Niacin extended-release tablet bioavailability by 2%.
Bile Acid Sequestrants
An in vitro study was carried out investigating the Niacin-binding capacity of colestipol and cholestyramine. About 98% of available Niacin was bound to colestipol, with 10 to 30% binding to cholestyramine.
References
- DailyMed. "NIACIN: DailyMed provides trustworthy information about marketed drugs in the United States. DailyMed is the official provider of FDA label information (package inserts).". https://dailymed.nlm.nih.gov/dailyme... (accessed September 17, 2018).
- NCIt. "Niacin: NCI Thesaurus (NCIt) provides reference terminology for many systems. It covers vocabulary for clinical care, translational and basic research, and public information and administrative activities.". https://ncit.nci.nih.gov/ncitbrowser... (accessed September 17, 2018).
- EPA DSStox. "Nicotinic acid: DSSTox provides a high quality public chemistry resource for supporting improved predictive toxicology.". https://comptox.epa.gov/dashboard/ds... (accessed September 17, 2018).
Reviews
The results of a survey conducted on ndrugs.com for Niacin are given in detail below. The results of the survey conducted are based on the impressions and views of the website users and consumers taking Niacin. We implore you to kindly base your medical condition or therapeutic choices on the result or test conducted by a physician or licensed medical practitioners.User reports
1 consumer reported administration
When best can I take Niacin, on an empty stomach, before or after food?ndrugs.com website users have also released a report stating that Niacin should be taken Empty stomach. In any case, this may not be the right description on how you ought to take this Niacin. Kindly visit your doctor for more medical advice in this regard. Click here to see other users view on when best the Niacin can be taken.
| Users | % | ||
|---|---|---|---|
| Empty stomach | 1 | 100.0% | |
Consumer reviews
There are no reviews yet. Be the first to write one! |
Information checked by Dr. Sachin Kumar, MD Pharmacology
