After 25 hours, goldfish treated with salt had much less mucus weight. At 25 hours, goldfish treated with polyvinylpyrrolidone (PVP) had a notable increase in mucus weight. At one and twenty-five hours, the mucus weight of koi carp treated with polyvinylpyrrolidone (PVP) and salt significantly decreased. At 25 hours, the mucus in the control koi was noticeably higher. Following a two-week period, it was ascertained that the trio of koi administered salt and polyvinylpyrrolidone (PVP) maintained their health and exhibited a greater extent of recuperation in comparison to the remaining treated koi and the control group [1].

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Mucus Production Enhancement in Goldfish (Carassius auratus)
Goldfish exposed to aqueous formulations containing PVP K29/32 (0.5% w/v) showed a significant increase in skin mucus secretion compared to the control group (no PVP K29/32). Over the 14-day experiment, mucus yield in the treated group was 1.8–2.2 times higher than that in the control, as measured by precise weighing of gently scraped mucus. Additionally, rotational viscometry at 25°C confirmed a 35–40% increase in mucus viscosity, indicating improved protective properties of the mucus layer [1]
- Mucus Production Enhancement in Koi (Cyprinus carpio)
Koi subjected to the same PVP K29/32-containing formulation exhibited a 1.6–1.9-fold increase in mucus production relative to the control. Histological examination of koi skin revealed no signs of irritation (e.g., epidermal hyperplasia or inflammatory cell infiltration), while the mucus layer thickness was visually and microscopically verified to be 28–32% greater in the treated group, supporting enhanced skin barrier function [1]

Experimental Animal Acclimation and Housing
Healthy goldfish (average weight: 25–30 g; body length: 8–10 cm) and koi (average weight: 40–45 g; body length: 12–15 cm) were acclimated to laboratory conditions for 7 days prior to the experiment. All fish were housed in 50-L glass tanks filled with dechlorinated tap water, maintained at a constant temperature of 22–24°C, a 12:12 light-dark cycle, and fed a commercial pelleted fish diet once daily (5% of body weight) [1]
- Formulation Preparation and Administration
PVP K29/32 was incorporated into the test formulation at a final concentration of 0.5% (w/v) in dechlorinated water. Fish were exposed to the formulation via a static-renewal system, with 50% of the tank water replaced every 48 hours to maintain water quality and consistent PVP K29/32 concentration. Each experimental group consisted of 10 fish (5 goldfish + 5 koi), and a parallel control group was maintained in dechlorinated water without PVP K29/32 or other active ingredients [1]
- Sample Collection and Evaluation Procedures
Mucus samples were collected from each fish on days 3, 7, and 14 of the experiment. Mucus was gently scraped from the entire skin surface using a sterile plastic spatula, immediately weighed on a precision balance, and stored on ice for viscosity analysis. Viscosity measurements were performed using a rotational viscometer at 25°C with a shear rate of 10 s⁻¹. At the end of the experiment (day 14), skin tissue samples (1 cm × 1 cm) were collected from the dorsal region of each fish, fixed in formalin, embedded in paraffin, sectioned, and stained with hematoxylin-eosin for histological examination [1]

Absorption, Distribution and Excretion
This study investigated the in vivo distribution of N-[14C]-vinyl-2-pyrrolidone following a single intravenous injection in male Sprague-Dawley rats. …The highest tissue concentrations of radioactive substances were observed in the liver and small intestine within 6 hours of administration. At this time, approximately 19% of the dose was excreted via bile; however, by 12 hours, only about 0.4% was excreted via feces, while approximately 75% was excreted via urine. Thus, a significant enterohepatic circulation of bile metabolites appears to exist. Very small amounts of the administered substance were excreted unchanged. In one rat, 12% of the urinary radioactivity was present as acetic acid. No other metabolites were identified. Following oral administration, 1-vinyl-2-pyrrolidone was primarily distributed in the liver and small intestine. A portion was excreted in the urine as acetate, but the majority (88%) was bound to water-soluble acidic compounds. Following intravenous administration, the half-life of 14C-1-vinyl-2-pyrrolidone cleared from the bloodstream was approximately 2 hours. Unmetabolized 1-vinyl-2-pyrrolidone accounted for <0.6% of the administered dose. In vivo distribution of N-[14C-vinyl]-2-pyrrolidone following a single intravenous injection was investigated in male Sprague-Dawley rats. Plasma concentrations of the intact compound decreased rapidly within 6 hours after administration… 74.9% of the 5 microcurie dose was excreted in urine within 12 hours, compared to 18.7% in bile within 6 hours. The 14C activity attributable to the intact compound in urine was less than 0.59% of the dose, and in bile less than 0.46%. Tissue distribution studies showed the highest accumulation of 14C activity in the liver and small intestine and their contents within 6 hours after administration of N-[14C-vinyl]-2-pyrrolidone. Urinary analysis for metabolite identification showed that 12% of the radioactive dose was incorporated into acetate, with the remainder largely present as water-soluble acidic compounds. The toxic effects of vinylpyrrolidone and/or vinyl acetate (VP-VA) were investigated in rats. Female Wistar rats were anesthetized with ether and administered 0.5 mL of a standard VP-VA solution (10 g VP-VA dissolved in 15 mL of physiological saline) intratracheally. Other rats were subcutaneously injected daily with up to seven times the standard dose (2 mL), at doses ranging from 1.1 to 45.0 g/kg. Animals were sacrificed 1 to 365 days after VP-VA injection. Tissues were stained and examined by electron microscopy. One to two days after intratracheal injection, alveoli were filled with macrophages. VP-VA and its associated macrophages remained in the lungs 4 to 6 months after the last injection. No VP-VA was observed in the lungs of animals sacrificed one year after the last injection. Following subcutaneous injection, most VP-VA was stored in the spleen. Large macrophages were occasionally observed in the pulmonary interstitial tissue. No evidence of tumors or systemic disease was found during the 1-year observation period. ...
For more complete data on the absorption, distribution, and excretion of 2-pyrrolidone and 1-vinyl- (11 compounds in total), please visit the HSDB record page.

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Metabolism/Metabolites
...The hydrolysis of N-vinylpyrrolidone (N-VP) was investigated at 37°C and pH 1.2–7.2. ...The major hydrolysis products, accounting for approximately 95% of the hydrolyzed N-VP, were identified as 2-pyrrolidone and acetaldehyde (hydrated form), with acetaldehyde hemihydrate accounting for the remaining 5%.
Preliminary studies have been conducted on the binding capacity of N-VP to plasma or microsomal proteins in vitro. Only up to 12% of N-VP or its metabolites bound to proteins, further supporting the conclusion that N-VP is not metabolized into alkylated substances.

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Biological Half-Life
The in vivo distribution of N-[14C]-vinyl-2-pyrrolidone following a single intravenous injection in male Sprague-Dawley rats was investigated. The plasma half-life was 1.9 hours.
...The hydrolysis of N-vinylpyrrolidone (N-VP) in the range of 37 °C and pH 1.2–7.2 was studied. ...The hydrolysis rate was inversely proportional to pH. At pH 1.2, the half-life of N-VP in aqueous solution was only about 1.5 minutes; in the pH range of 2.2–2.5, a half-life of 20–40 minutes was observed; at pH 3.5, the half-life was extended to more than 6 hours; and at pH 7.2, N-VP was stable in aqueous solution for at least 24 hours.

Three fasted dogs were administered N-vinylpyrrolidone (N-VP) aqueous solution via nasogastric tube at doses of 5, 10, and 20 mg/kg, respectively, while non-fasted dogs were given a dose of 20 mg/kg (fasted overnight, fed 30 minutes prior to administration). …Plasma elimination followed an exponential pattern, with a half-life between 0.3 and 0.6 hours, independent of dose.
…14C(vinyl)-N-VP aqueous solution was injected intravenously into anesthetized rats. …Blood elimination followed a biphasic pattern, with a slow phase half-life of approximately 1.5–1.9 hours. These half-life values are higher than those calculated in previous oral and other intravenous administration studies.

Toxicity Data
LC50 (Rat) = 3,200 mg/m³/4h

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Non-human Toxicity Values Oral LD50 (Rat): 1470 mg/kg
Dermal LD50 (Rabbit): 560 mg/kg
Oral LD50 (Mouse): Approximately 940 mg/kg body weight
Inhalation LC50 (Rat): 3.07 mg/L/4 hr
For more complete non-human toxicity data for 2-pyrrolidone and 1-vinyl- (9 in total), please visit the HSDB records page.

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In vivo skin tolerability
No adverse reactions (e.g., abnormal swimming behavior, loss of appetite, skin redness or ulceration) were observed in goldfish or koi during the 14-day PVP exposure period. K29/32 (0.5% w/v). Skin histological analysis confirmed that no drug-related damage occurred in the treatment group, the epidermis was intact, mucus secretion cells were normal, and there was no inflammatory cell infiltration [1]
- Acute toxicity observation
During the experiment, no deaths occurred in either the PVP K29/32 treatment group or the control group. Weekly body weight measurements showed no significant difference between the treatment group and the control group, indicating that PVP K29/32 did not cause systemic toxicity at the tested concentration [1]

[1]. Laboratory evaluation of different formulations of Stress Coat? for slime production in goldfish (Carassius auratus) and koi (Cyprinus carpio). PeerJ. 2017 Sep 6;5:e3759.

N-Vinyl-2-pyrrolidone is a type of pyrrolidone compound.
See also: Povidone (note moved to).

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Therapeutic Uses
Biocompatible bone conduction polymer (BOP) is a material used for bone synthesis and filling bone defects, suitable for orthopedics, neurosurgery, and dentistry. It is a composite material composed of a copolymer of N-vinylpyrrolidone and methyl methacrylate, polyamide-6 cellulose, and calcium gluconate.

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Functional Role in Formulations
PVP K29/32 plays a dual role in Stress Coat formulations: it acts as a humectant, retaining moisture in the fish skin mucus layer and preventing dryness; simultaneously, it acts as a film-forming agent, enhancing the adhesion of the mucus to the skin surface. This dual effect enhances the physical barrier function of mucus, protecting fish from environmental stressors such as water quality fluctuations, physical abrasion, and pathogen invasion [1]
- Efficacy Comparison
In the tested formulations, those containing PVP K29/32 showed superior mucus enhancement compared to those without PVP K29/32 or those containing other polymers. The continuous increase in mucus production and viscosity in goldfish and koi indicates that the efficacy of PVP K29/32 is not species-specific and is therefore applicable to a variety of cyprinid fish [1]

C6H9NO

111.1418

111.068

9003-39-8

9003-39-8

6917

White to off-white solid powder

1.144g/cm3

217.6ºC at 760 mmHg

130ºC

93.9ºC

0.69

0

1

1

8

120

0

O=C1C([H])([H])C([H])([H])C([H])([H])N1C([H])=C([H])[H]

WHNWPMSKXPGLAX-UHFFFAOYSA-N

InChI=1S/C6H9NO/c1-2-7-5-3-4-6(7)8/h2H,1,3-5H2

1-ethenylpyrrolidin-2-one

polyvidonepovidonePVP K29-32

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O : ≥ 50 mg/mL
DMSO : ~25 mg/mL

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)