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Frequently Asked Questions

Does Naltrexone contain filler ingredients?

Short Answer

Yes.

Long Answer

Like other drugs produced by pharmaceutical companies, Naltrexone tablets contain inactive ingredients along with the active ingredient - in this case, Naltrexone. These inactive ingredients are called excipients but are commonly referred to as fillers. Fillers serve a number of different purposes in the manufacture of medicinal drugs. Examples of their use are to increase the bulk or volume of the ingredients, bind ingredients together, or help a tablet dissolve in the stomach faster.

Patients being treated with low-dose Naltrexone (LDN) may have concerns about the presence of fillers. LDN can be made in the following ways:

  • A compounding pharmacy mixes pure Naltrexone powder with distilled water, producing a filler-free liquid product.
  • A compounding pharmacy mixes pure Naltrexone powder with a filler and measures the dry ingredients into capsules.
  • A compounding pharmacy or a patient crushes a commercial Naltrexone tablet (along with its fillers) and mixes it with distilled water to dilute the product so it can be taken in small, accurately-measured doses.

Compounding pharmacies that add their own fillers to pure Naltrexone powder will be able to tell you the type of filler(s) they use. The fillers contained in the third option using Naltrexone tablets aren't a problem for most people but those who are sensitive to certain filler ingredients may experience a negative reaction.

Naltrexone 50 mg tablets contain the following inactive ingredients:

  • Colloidal silicon dioxide
  • Crospovidone
  • Lactose monohydrate
  • Magnesium stearate
  • Microcrystalline cellulose (Avicel)
  • Pale Yellow Opadry YS-1-6378-G, a colouring agent that contains:
    • Hypromellose (Hydroxypropyl methylcellulose)
    • Macrogol (Polyethylene glycol)
    • Polysorbate 80
    • Titanium dioxide
    • Yellow and red iron oxides
Colloidal silicon dioxide
Colloidal silicon dioxide, also known as silica and silicon dioxide, is obtained by mining and processing sand or quartz. It's used in the food and pharmaceutical industry. Since silicon dioxide is highly absorbent, it's used as a glidant to make the powdered ingredients flow more smoothly as the mixture is being poured to form tablets.
Crospovidone
Crospovidone is a type of excipient known as a disintegrant. When it comes in contact with liquids in the digestive tract, it expands to allow the tablet to break apart so the active ingredient can be absorbed.
Hypromellose
Hypromellose, also called hydroxypropyl methylcellulose or HPMC, is a component of Pale Yellow Opadry and is used as a coating to make tablets easier to swallow.
Lactose monohydrate
Lactose monohydrate, also called lactose, is milk sugar. It's used to bind tablets together. People who are lactose intolerant may experience a reaction to lactose monohydrate. The amount used in Naltrexone is very small so it's more likely that only people with severe lactose intolerance will be affected.
Macrogol (polyethylene glycol)
Macrogol or polyethylene glycol is a component of Pale Yellow Opadry. According to Drugs.com, "Polyethylene glycol, referred to as PEG, is used as an inactive ingredient in the pharmaceutical industry as a solvent, plasticizer, surfactant, ointment and suppository base, and tablet and capsule lubricant. PEG has low toxicity with absorption into the body less than 0.5%." The formulation used is polyethylene glycol 400 as opposed to polyethylene glycol 3350 which is used as a laxative.
Magnesium stearate
Magnesium stearate is magnesium salt containing stearic acid which is commonly found in fatty foods. It's widely used in the pharmaceutical industry as a lubricant to prevent ingredients from sticking together and from adhering to the machinery that compresses the ingredients into tablet form.

There's a great deal of controversy about its safety. Most of the objections come from the dietary supplement industry that promotes natural products. Magnesium stearate is FDA-approved. The FDA states, "There is no evidence in the available information on magnesium carbonate, magnesium chloride, magnesium sulfate, magnesium hydroxide, magnesium oxide, magnesium stearate, dibasic magnesium phosphate and tribasic magnesium phosphate that demonstrates, or suggests reasonable grounds to suspect, a hazard to the public when they are used at levels that are now current and in the manner now practiced, or which might reasonably be expected in the future."
Microcrystalline cellulose (Avicel)
Microcrystalline cellulose is refined wood pulp sold under the brand name Avicel. It's a versatile and safe substance commonly used in food and pharmaceutical products. Drug manufacturers use it to bind ingredients together.
Polysorbate 80
Polysorbate 80 is a component of Pale Yellow Opadry. It is used in food, cosmetics, and pharmaceutical products such as vaccines and tablets. In manufacturing tablets it's a solubilizing agent used to dissolve one ingredient into another.
Red iron oxide
Red iron oxide or ferric oxide red is a component of Pale Yellow Opadry and is used to colour pharmaceutical tablets and capsules. Ferric oxide red is a natural substance found in hematite ore and rust. Synthetic versions may also be used in pharmaceuticals.
Titanium dioxide
Titanium dioxide is an FDA-approved component of Pale Yellow Opadry and is a commonly used colourant in the food, pharmaceutical, and cosmetics industries. There have been some safety concerns about titanium dioxide nano-particles that are used in cosmetics and sunscreens. This doesn't apply to titanium dioxide used in food and drug products because the particles are much larger.
Yellow iron oxide
Yellow iron oxide or ferric oxide yellow is a component of Pale Yellow Opadry and is used as a coating pigment in the pharmaceutical and cosmetics industries.

Additional Information

Overview of pharmaceutical excipients used in tablets and capsules (DrugTopics.ModernMedicine.com)
Drug Topics discusses different classes of excipients and lists 94 excipients and their uses.
Excipient (Wikipedia.org)
Wikipedia covers different types of excipients and gives examples of each type.
The Facts on Magnesium Stearate
Byron J. Richards, Board Certified Clinical Nutritionist, explains what magnesium stearate is and debunks claims of its dangers.
Database of Select Committee on GRAS Substances (SCOGS) Reviews - Magnesium stearate (FDA.gov)
"The Select Committee concludes that: There is no evidence in the available information on magnesium carbonate, magnesium chloride, magnesium sulfate, magnesium hydroxide, magnesium oxide, magnesium stearate, dibasic magnesium phosphate and tribasic magnesium phosphate that demonstrates, or suggests reasonable grounds to suspect, a hazard to the public when they are used at levels that are now current and in the manner now practiced, or which might reasonably be expected in the future."
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