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Plaquenil and Quinoric

By A. G. Moore 
This week I read several posts on Lupus UK which addressed the question of whether Quinoric was as effective as Plaquenil in treating lupus. Several people on the site suggested that the only difference between the two drugs was in the “filler” added to the active ingredient, hydroxychloroquine. And several people added that their pharmacist, or doctor, had assured them the preparations were “identical”. Which suggests to me a larger issue: are generics and substitute formulations for established drugs truly “identical” in formulation and do they behave identically when consumed?

In an effort to examine the interchangeability of generics for established drugs, I took a close look at Plaquenil and Quinoric. Are these two “identical”? Can one drug be substituted seamlessly for the other? I found a list of constituent ingredients for each of these drugs so I could make a comparison.

Both drugs, I discovered, do contain the same active ingredient in equal quantity: 200 mgs of hydroxychloroquine. The differences between the drugs, as some people suspected, is in the “fillers”. So I looked at those “fillers”.

Plaquenil (Manufacturer Sanofi. List derived from:

Calcium Phosphate, Dibasic, Anhydrous


Magnesium Stearate

Polyethylene glycol 400

Polysorbate 80

Starch, Corn

Titanium Dioxide

Quinoric (Manufacturer Bristol Labs. List derived from

Maize Starch

Calcium Hydrogen Phosphate dihydrate

Colloidal anhydrous silica

Polysorbate 80

Purified Tale

Magnesium stearate


Titanium dioxide

Macrogol 6000

While the two lists of constituent ingredients are similar, they certainly are not the same. But the question remains, do these differences matter? I took a look at one ingredient that appears to be almost identical.: PEG.

On the Plaquenil list PEG (Polyethylene glycol) is described as Polyethylene glycol 400. On the Quinoric list PEG comes in a different formulation: Macrogol 6000. In industry, these two forms of PEG have different uses because they interact with environments differently. One, Macrogol 6000, is commonly used as a laxative, among other things. The other, Polyethylene glycol 400, has a lower molecular weight and is more liquid: this chemical is often used in printer ink, as well as in pharmaceuticl preparations. It’s impossible for me to say if these two forms of PEG are processed identically in the human body.

There’s one “filler” included on the list for Quinoric which is not included on the list for Plaquenil: silica (Colloidal anydrous silica). Silica is abundant in the environment. This compound has been linked to a numboer of autimmune diseases. Whether inhaled, absorbed through the skin or ingested orally, silica has a well-established association with lupus and rheumatoid arthritis, among other other inflammatory conditions. Silica is almost ubiquitous. It’s in soaps, cleaning products, paints and other common household items. Some sources that discuss silica’s role in autoimmunity are:

So, I ask,  what is silica doing in a preparation that’s prescribed for people who have lupus?

There is a pat response to this and other questions I raise in this essay: these substances are harmless, they are inactive and largely inert. They serve merely as vehicles for delivery of crucial medication.

I’m going to refute these glib reassurances by turning to Dr. Phil Lieberman of the American Academy of Asthma, Allergy & Immunology. Dr. Liebermans is asked about an adverse reaction a patient had to one constituent ingredient in Quinoric: Macrolog 6000. The doctor responds: “ is best to try and avoid polyethylene glycol as carefully as possible. This is a difficult task given the ubiquitous nature of these substances, but it is clearly the safest strategy to employ.”( see: ).

I’m not a chemist, pharmacist or doctor. But I do know what the word identical means. And I do know that when there is a change in formulation—say from PEG 400 to Macrolog 6000—it’s because one formulation behaves differently from another. And if two substances are not the same, then they are not the same.

Plaquenil and Quinoric are prescribed for a very particular population, a population of people who have heightened immune responses. Allergies, even rare allergies, are common in this population. Extreme caution should be taken when introducing any new element into the environment of someone with such a heightened and unpredictable response to potential antagonists.

Plaquenil and Quinoric are not identical; they may not be absorbed the same into the bloodstream, or processed in exactly the same way by the digestive system. There may be constituent ingredients that are irritating in one and not the other.

This issue is not unique to Plaquenil and Quinoric; the issue of interchangeability between knock-off drugs and brand name drugs is one that affects every single person who has to take medicine: that is, all of us. Glib rejoinders that medicines are “identical” do not address the matter. More honest would be an admission that there are differences in manufacturing and processing between knock-offs and brand drugs. For most people, in most cases, these differences may have no consequence. However, there’s no telling how a particular formulation will be tolerated by a particular individual.

This is the truth—perhaps not convenient, but nonetheless true. And truth is something every patient has a right to expect from a medical provider.

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