Crospovidone (Polyvinylpolypyrrolidone / PVPP)
1. Identity, Nomenclature, and Chemical Character
A chemically precise name for E 1202 is "crosslinked polyvinylpyrrolidone," with synonyms including Crospovidone, Crospovidonum, insoluble polyvinylpyrrolidone, cross-linked PVP, and PVPP. It is also referred to as crospolividone and carries the food-additive code E1202. The substance bears two commonly cited CAS numbers: CAS No. 9003-39-8 and 25249-54-1. Its molecular formula is (C₆H₉NO)ₙ.
The name "polyvinylpolypyrrolidone" and the abbreviation PVPP are chemically inaccurate designations, although they have been widely used and accepted. A more accurate name is "crosslinked polyvinylpyrrolidone," defined as a crosslinked homopolymer of N-vinyl-2-pyrrolidone produced catalytically that is insoluble in water and other common solvents.
Crospovidone is entirely synthetic and has no botanical source. It is an insoluble form of polyvinylpyrrolidone. This highly cross-linked polymer is derived from the monomer N-vinyl-2-pyrrolidone. It appears as a white to creamy-white, finely divided, free-flowing, practically tasteless, odorless or nearly odorless, hygroscopic powder.
Physical Properties
Crospovidone is insoluble in water, though it still absorbs water and swells very rapidly, generating a swelling force. Crospovidone is not substituted and lacks ionizable groups; therefore, molecular properties of crospovidone are unlikely to affect the excipient's functionality. Being nonionic in nature, the disintegration efficiency of crospovidone is independent of the pH of media and thus is a potentially suitable disintegrant for cationic drugs.
Commercial Grades and Trade Names
The USP–NF monograph distinguishes Type A and Type B, determined by particle size. Specific commercial products include Kollidon CL (manufactured by BASF), Polyplasdone XL (manufactured by ISP), and Polyplasdone XL-10 (manufactured by ISP). Two particle size grades exist for disintegration: Polyplasdone XL and XL-10. With its smaller particle size, Polyplasdone XL-10 gives excellent content uniformity in intragranular application and in small tablets (less than 300 mg), and also gives a smoother mouth feel in quick-dissolve and chewable formulations. Polyplasdone Ultra and Polyplasdone Ultra-10 grades have significantly lower peroxide levels than standard forms of crospovidone — more than ten times lower — and have more stringent specifications than current requirements of the European Pharmacopeia monograph.
Pharmacopeial Status
Crospovidone is compliant with USP/NF, EP (European Pharmacopoeia), JP (Japanese Pharmacopoeia), and BP (British Pharmacopoeia) standards. USP's revision of the standard for Crospovidone has been approved by the Pharmacopeial Discussion Group (PDG), incorporating internationally harmonized monograph criteria. It is included in the FDA Inactive Ingredients Database for intramuscular injections, oral capsules and tablets, and topical, transdermal, and vaginal preparations. It is also included in non-parenteral medicines licensed in the UK.
2. History and Background of the Parent Polymer Family
Povidone (the soluble precursor, PVP) was first synthesized by BASF chemist Walter Reppe, and a patent was filed in 1939 for one of the derivatives of acetylene chemistry. PVP was initially used as a blood plasma substitute and later in a wide variety of applications in medicine, pharmacy, cosmetics, and industrial production.
Polyvinylpyrrolidone was initially used as a blood plasma substitute in the Second World War. Afterwards, it began to be utilized in a multiplicity of sectors, including the pharmaceutical, cosmetic, and detergent industries. The cross-linked, insoluble form — crospovidone — was subsequently developed as a distinct material with different physical properties suited specifically to tablet manufacturing and beverage processing. Highly crosslinked or insoluble PVP, known as crospovidone, was made by popcorn or proliferous polymerization of vinylpyrrolidone.
Crospovidone itself does not have a history of traditional or ethnobotanical use. It is a fully synthetic material with no analogue in pre-modern medicine. Its history is entirely that of industrial chemistry and modern pharmaceutical development, spanning from the mid-twentieth century onward. It is also commonly used as a clarifier in alcoholic and nonalcoholic beverages, a use that developed alongside the food and beverage industry's adoption of PVPP from the second half of the twentieth century.
3. Synthesis and Manufacturing
Acetylene and formaldehyde are reacted in the presence of a highly active catalyst to form butynediol, which is hydrogenated to butanediol and then cyclodehydrogenated to form butyrolactone. Pyrrolidone is produced by reacting butyrolactone with ammonia. This is followed by a vinylation reaction in which pyrrolidone and acetylene are reacted under pressure. The monomer vinylpyrrolidone is then polymerized in solution using a catalyst, and crospovidone is prepared by a "popcorn polymerization" process.
Crospovidone is manufactured through a popcorn polymerization technique (proliferous polymerization) of the initial monomer, leading to the formation of porous particles. This popcorn polymerization leads to insoluble PVP, whereby vinylpyrrolidone is polymerized without initiator in the presence of small amounts of bifunctional monomers. The resulting material is known as a "popcorn" polymer, where the popped structure resembles a polymer foam, with voids created by the polymerization process.
An alternative synthesis pathway for crospovidone was developed by Hofman and Herrle, where vinylpyrrolidone polymerization was carried out in the presence of cross-linking reagents N,N-divinyl imidazolidon and radical initiators such as AIBN and organic peroxides.
4. Key Constituents and Chemical Structure
From a structural point of view, crospovidone can be regarded as a polyvinyl pyrrolidone (PVP) molecular chain with a linear molecular structure cross-linked by physical or chemical methods, so crospovidone can also be called cross-linked PVP or insoluble PVP. Crospovidone is a water-insoluble nonionic polymer consisting of cross-linked 1-vinyl-2-pyrrolidone monomers.
A critical quality consideration is residual peroxide content from the manufacturing process. The residual peroxides in crospovidone can affect the stability of oxygen-sensitive molecules. Hartauer et al. observed an oxidative degradation product of raloxifene hydrochloride in a tablet formulation identified as an N-oxide derivative; results from drug-excipient studies and a formulation spiking study showed that residual peroxides in crospovidone promoted the formation of the N-oxide. EU specifications for PVPP (E 1202) now include limits for peroxide content.
Owing to its crosslinked nature, crospovidone is completely insoluble in water, yet it retains hydrophilicity and hygroscopicity. For a polymer to be useful as a pharmaceutical excipient, grades of material need to possess properties such as high swelling capacity, high capillary activity, high hydration capacity, and low bulk density.
5. Mechanisms of Action
5.1 Tablet Disintegration (Superdisintegrant Function)
Unlike other superdisintegrants, which rely principally on swelling for disintegration, crospovidone uses a combination of mechanisms to provide rapid disintegration. Although crospovidone polymers swell by 95% to 120% upon contact with water, swelling is not the only mechanism for tablet disintegration.
The three established mechanisms are:
- Swelling: The primary mechanism is rapid swelling. Upon contact with water or other aqueous media, the cross-linked polymer chains readily absorb moisture. This absorption causes the polymer network to expand significantly, creating internal pressure within the tablet matrix. This pressure overcomes the cohesive forces holding the tablet together, leading to rapid breakdown into smaller fragments.
- Wicking: Crospovidone polymers, with their porous particle morphology, rapidly absorb water (wicking) via capillary action. This action helps to maintain the capillary channels within the tablet, ensuring that water can continue to reach the disintegrant particles, promoting a consistent and rapid disintegration process.
- Strain recovery: During tablet compaction, the highly compressible crospovidone particles become highly deformed. As the deformed crospovidone particles come in contact with water wicked into the tablet, the crospovidone particles recover their normal structure and swell, resulting in rapid volume expansion and hydrostatic pressures that cause tablet disintegration. Researchers concluded that the superdisintegrant crospovidone works mainly by this strain recovery mechanism.
Unlike some other hydrophilic polymers that can form viscous gels, crospovidone typically maintains its structural integrity during swelling, avoiding the formation of a gel barrier that might impede drug release. The disintegration rate of tablets containing sodium starch glycolate or croscarmellose sodium decreases in acidic media, but that of tablets containing crospovidone is unaffected.
5.2 Polyphenol and Tannin Adsorption
PVPP forms bonds similar to peptidic bonds in protein — especially like proline residues — and that is why it can precipitate tannins the same way as proteins do. This mechanism underlies its use as a beverage clarifier and its proposed medical use as an intestinal adsorbent.
5.3 Endotoxin / Enterotoxin Adsorption
Crospovidone has advantageous properties including absorption of certain compounds like endotoxins that may cause diarrhea. PVPP can be used as a drug, taken as a tablet or suspension to absorb compounds (so-called endotoxins) that cause diarrhea. This adsorptive property, arising from the same hydrogen-bonding and hydrophobic interaction capacity that enables polyphenol binding, positions crospovidone as a non-systemic intestinal adsorbent in some therapeutic applications.
6. Areas of Use and Scientific Evidence
6.1 Pharmaceutical Tablet Disintegration and Drug Bioavailability
Nature of the evidence: Established pharmaceutical science; extensively documented in formulation literature, pharmacopeial monographs, and in-vitro and in-vivo studies. This is the most thoroughly supported application of crospovidone.
The primary function of crospovidone in pharmaceutical formulations is as a superdisintegrant. Unlike traditional disintegrants, crospovidone exhibits rapid swelling and wicking capabilities; when incorporated into a tablet, it quickly absorbs fluids, initiating a rapid disintegration process. This swelling action exerts pressure on the tablet matrix, causing it to disintegrate quickly into smaller particles, which is essential for immediate-release formulations as it increases the surface area available for drug dissolution, thereby accelerating the absorption rate in the gastrointestinal tract.
Crospovidone levels higher than 8% of tablet weight produce weaker tablets with faster disintegration. It may be used in concentrations of 2%–5% in tablet formulations. In dispersible tablet formulations, the amount of disintegrant normally present is from 5–10% (w/w); in some cases, amounts as low as 2% (w/w) have been reported. For orally disintegrating tablets in one study context, disintegrants including crospovidone are used in an amount of about 1 to 15 weight%, preferably about 1 to 10 weight%, more preferably about 3 to 7 weight%.
Crospovidone is defined as a cross-linked, water-insoluble superdisintegrant that appears as a white, free-flowing, hygroscopic powder, commonly used in tablet formulations to facilitate disintegration by swelling. It can also enhance the solubility of poorly soluble drugs through coevaporation techniques.
6.2 Beverage Clarification (Beer and Wine)
Nature of the evidence: Well-established industrial and food-science application supported by regulatory approval and long-standing commercial use. No controlled clinical trials are relevant to this application.
PVPP effectively removes polyphenols and tannins in beverages like beer and wine, where it acts as a clarifying and stabilizing agent. Using this principle, crospovidone is used to remove polyphenols in beer production, producing clear beers with stable foam. PVPP (crospovidone) carries EU food additive code E1202 and is used in the wine industry as a fining agent for white wine and some beers.
The EFSA Panel on Food Additives re-evaluated polyvinylpyrrolidone (E 1201) and polyvinylpolypyrrolidone (E 1202) when used as food additives in 2020. As part of that review, EFSA recommended including limits for several elements of toxicological importance (arsenic, cadmium, mercury, chromium, cobalt, copper, and nickel) in EU specifications for PVP and PVPP, and including a limit for peroxide content in the EU specifications for PVPP (E 1202).
6.3 Gastrointestinal Conditions (Intestinal Adsorbent / Diarrhea)
Nature of the evidence: Limited. The use of crospovidone as an intestinal adsorbent is documented in the literature but formal human clinical trial data confirming its efficacy as a primary treatment for diarrhea are sparse in the publicly available evidence base.
Crospovidone is medically used for the treatment of some intestinal disorders as solubilizing excipients to improve the bioavailability of drugs (such as steroids) and as germicides in wound treatment. In some countries, including France, crospovidone is given as a treatment for certain gastrointestinal conditions, where it coats the intestinal lining and adsorbs bacterial toxins. Crospovidone is not absorbed orally, which supports its role as a luminal adsorbent: it remains within the gut and is excreted intact in the stool, carrying bound compounds with it.
The proposed mechanism — PVPP can be used as a drug, taken as a tablet or suspension to absorb compounds (so-called endotoxins) that cause diarrhea — parallels those of other oral adsorbents such as activated charcoal. However, the strength of clinical evidence for crospovidone in this indication specifically is weak relative to its pharmaceutical excipient applications; rigorous human randomized controlled trials have not been prominently published in the indexed literature reviewed here.
6.4 Wound Treatment and Topical Application
Nature of the evidence: Preliminary, largely at the material-science and pre-clinical level.
Crospovidone is used as a germicide in wound treatment. Irradiation-cross-linked PVPP can be hydrated into transparent, conformable hydrogels with 90–95% water content for cooling and debridement, with an elastic modulus of 10–30 kPa (matching soft tissue), and low extractables and endotoxin levels within medical limits. Manufacturers blend PVPP with polyethylene glycol (PEG) or alginate to modulate adhesion and vertical fluid wicking, creating hydrogel sheets that can be printed in custom shapes for burns or chronic ulcers. Rigorous clinical trial data on crospovidone-based wound dressings in humans was not identified in the sources reviewed; this application remains at a developmental or niche-commercial stage.
7. Body Systems Associated with Crospovidone
- Gastrointestinal system: As a tablet disintegrant, crospovidone directly determines how rapidly a solid dosage form dissolves in the gastrointestinal tract, affecting absorption of active ingredients. As a proposed intestinal adsorbent, it acts within the GI lumen to bind and remove endotoxins.
- Pulmonary system: Relevant specifically in the context of misuse (see Safety section). Crospovidone is an insoluble polymer of N-vinyl-2-pyrrolidone used as a disintegrant in pharmaceutical tablets. It can potentially embolize to the lung when aqueous tablet suspensions are injected intravenously.
- Immune system / lymphatic system: In animal studies, some immune cells in lymph nodes near the intestines showed signs of clearing the ingested material, described as a normal housekeeping response rather than a toxic one.
- Integumentary system (skin/wounds): In cross-linked hydrogel form, under investigation for wound management (see Section 6.4).
8. Dosage Forms and Reported Dosages
Crospovidone is encountered primarily as an excipient rather than as a standalone therapeutic agent. Reported concentrations and amounts in the literature include:
- In tablet formulations as a disintegrant: 2%–5% concentration.
- In dispersible tablets: normally 5–10% (w/w); in some cases as low as 2% (w/w).
- In orally disintegrating tablets: about 1–15 weight%, preferably 1–10 weight%, more preferably 3–7 weight%, relative to 100 weight% of the tablet.
- Crospovidone levels higher than 8% of tablet weight produce weaker tablets with faster disintegration.
Dosage forms in which crospovidone appears include: intramuscular injections (as an excipient), oral capsules and tablets, and topical, transdermal, and vaginal preparations. Crospovidone is used as a super disintegrant in tablets and suppositories due to its high swelling properties.
As regards an acceptable daily intake (ADI) for humans: owing to the lack of available data, an acceptable daily intake in humans has not been specified by the WHO.
9. Safety Considerations and Drug Interactions
9.1 Oral Toxicity
Crospovidone is used in oral pharmaceutical formulations and is generally regarded as a nontoxic and nonirritant material. Short-term animal toxicity studies have shown no adverse effects associated with crospovidone. Assessment of acute toxicity describes crospovidone as virtually nontoxic after a single ingestion and virtually nontoxic by inhalation. Experimental data include an LD50 in rats (oral) of greater than 2,000 mg/kg. It is not irritating to the skin or eyes.
The most relevant safety data come from chronic toxicity studies in rats and dogs. Rats were fed a closely related polymer at doses up to 2,800 mg per kilogram of body weight daily for two full years; dogs received up to 2,500 mg/kg daily for a year. In both species, researchers found no treatment-related blood changes, no organ damage, and no cancerous growths. The only observable effect in rats was darker stool from excreting large amounts of the substance, which was not considered harmful.
Copovidone and crospovidone are found to be safe with no toxicological reports and good tolerance.
9.2 Non-Absorption and Gut Confinement
Crospovidone is not absorbed orally. This is a direct consequence of its high molecular weight and insoluble cross-linked structure. When taken orally, it transits the gastrointestinal tract intact and is excreted in the feces. This property is central to both its safety profile and its mechanism as a luminal adsorbent.
9.3 Pulmonary Injury from Intravenous Misuse
The most serious documented safety issue with crospovidone involves its intravenous injection by individuals who crush and dissolve oral tablets intended for oral consumption only. Embolized crospovidone has been identified in autopsy-derived lung tissue of three intravenous drug users, representing a distinctive embolic material that is an important disintegrant in pharmaceutical tablets. Crospovidone has not generally been emphasized, or recognized by pathologists, as a cause of pulmonary angiothrombosis and foreign body granulomatosis.
It is concluded that crospovidone contributes to pulmonary vascular injury in some persons who illicitly inject pharmaceutical tablets. Pulmonary talcosis is a rare granulomatous lung disease resulting from the intravenous injection of crushed oral tablets containing insoluble excipients such as talc, microcrystalline cellulose, and crospovidone. These substances embolize within the pulmonary vasculature, provoking granulomatous inflammation that may progress to pulmonary arterial hypertension (PAH).
In the published case series by Ganesan et al. (2003), embolized crospovidone was identified in autopsy-derived lung tissue from three adult IV drug users aged 27, 38, and 40 years. Suspected crospovidone was compared with pharmaceutical-grade crospovidone by means of histochemical stains, transmission electron microscopy, and infrared spectroscopy. Similar particles were also observed by light microscopy in a 4-mg tablet of hydromorphone, a preparation prescribed to two of the patients.
The long-term effects of crospovidone in the lung are unknown. These cases are specific to injection drug use and represent a fundamentally different exposure route than swallowing a tablet. When taken orally as designed, crospovidone stays in the gut and never reaches the bloodstream.
9.4 Allergic Reactions
True allergic reactions to crospovidone are uncommon, but they do exist. Povidone, the soluble form of the same polymer family, has triggered anaphylaxis in rare cases after exposure through oral tablets, eye drops, facial creams, and injected corticosteroids. If an individual has a confirmed allergy to povidone, they may also react to crospovidone. Allergists consider the two cross-reactive, meaning the immune system can mistake one for the other.
Allergic reactions have also been reported with the use of povidone-iodine (Betadine®) as a topical antiseptic. Povidone-iodine contains iodine bonded to povidone, but a povidone allergy is not the same as an iodine allergy or a reaction to radiocontrast dyes used in medical imaging; these are separate immune pathways.
9.5 Drug-Excipient Incompatibilities
Crospovidone is compatible with most organic and inorganic pharmaceutical ingredients. When exposed to a high water level, crospovidone may form molecular adducts with some materials. The most clinically significant incompatibility relates to peroxide-sensitive active pharmaceutical ingredients (APIs): residual peroxides in crospovidone can affect the stability of oxygen-sensitive molecules. Polymeric excipients such as polyvinylpyrrolidones often use peroxides to initiate the polymerization reaction, and it is generally thought that this is the primary source of oxidants in polymeric excipients as it is difficult to completely eliminate them from the final product.
9.6 Regulatory Oversight and Identified Data Gaps
The FDA identified crospovidone as a priority excipient for monograph updating, citing potential health issues as the basis for this request. EFSA's 2020 re-evaluation recommended including data on the potential presence of nanoparticles in PVPP (E 1202), reflecting an open question about whether nanoscale particles of crospovidone may have different absorption or biological behavior compared to the bulk material.
References
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