Agent In Pharmaceutical Formulations Research Articles

An Exploration of The Potential of Natural Super Disintegrating Agents in Pharmaceutical Formulations: A Review

This review delves into the use of natural super disintegrating agents in pharmaceutical drug formulations. Disintegrants are incorporated into these formulations to aid in breaking down tablets and capsules, promoting rapid dissolution by facilitating their dispersion into smaller particles. Super disintegrants, distinguished by their notable swelling capacity, play a pivotal role in expediting drug disintegration within the gastrointestinal tract. The selection of an appropriate super disintegrant hinges on several factors, including chemical compatibility, swelling potential, disintegration speed, particle size, cost, manufacturing methods, and adherence to regulatory standards. The piece elucidates the diverse mechanisms through which super disintegrants foster the disintegration of solid dosage forms. These mechanisms encompass swelling, wicking, heat-induced wetting, chemical reactions, particle repulsion, and deformation recovery. A comprehensive grasp of super disintegrants' properties and mechanisms is indispensable for ensuring the effectiveness, safety, and cost-efficiency of drug formulations. This review article critically examines existing literature, offering a valuable resource for researchers and pharmaceutical professionals engaged in the development of efficient and safe pharmaceutical products.

Effect of honey use with Seriphidium chitralense podlech on growth and biofilm formation of Pseudomonasaeruginosa

The combined use of honey and medicial plants has a history of traditional usage in various ailments. The present work is a scientific evaluation of honey and crude extracts of Seriphidium chitralense Pod (Sc) against Pseudomonas aeruginosa (Pa) biofilms. Biofilms are intricate microbial communities linked with insistent infections showing increased antimicrobial and immunological resistance. The agar well diffusion (AWD) method has been used to determine antimicrobial activities. The broth microdilution method was used to determine the MIC of honey (Manuka and Gilgit honey) and different plant extracts against Pa. Both honey and extracts exhibited anti-bacterial activity against the test organism, in which Gilgit honey and aqueous extract showed significant anti-bacterial activity. In the case of AWD, Gilgit honey showed low activity at a concentration of 10%, while Manuka honey showed low activity at 5%. This study also reports the inhibitory effect of honey and medicinal plants on biofilm formation by Pa. The plant extract was prepared in ethyl acetate, methanol, and distilled water. Plant extract in distilled water showed maximum biofilm inhibition compared to methanol and ethyl acetate in M63 medium. MICs of honey with Sc extracts were determined to search for synergistic combinations against Pa, which showed anti-bacterial solid activity compared to honey and plant extract alone. Manuka honey, in combination with aqueous extracts, showed high activity (0.0266), and Gilgit honey, in combination with aqueous extracts, showed significant activity (0.0432) compared to the other Sc extracts. The results of this study revealed that honey-plant extract mixtures have the potential to serve as a cheap source of anti-bacterial agents in pharmaceutical formulations and alternative products.

Solid State Kinetics of Nitrosation Using Native Sources of Nitrite

While many reactive species are known to cause N-nitrosation, trace nitrite (NO2−), which may be present in several excipients, is a source of nitrosating agents in pharmaceutical formulations. In this study we have found that the salt form of NO2− can influence the favored nitrosation conditions and final amount of nitrosamine being formed. Using native levels of NO2−, most likely present as ammonium nitrite (NH4NO2), in microcrystalline cellulose, we have determined the kinetics of nitrosamine formation in solid state with dimethylamine substrate present in metformin, used as model compound. It was found that the competing degradation of NH4NO2 into N2 and H2O limited the amount of nitrosamine formation to a great extent. Empirically modelling the kinetic data predicted reaching at maximum 1.6% conversion over a hypothetical 3-year shelf-life. These results also showed that using other sources of NO2− as spiking reagents, such as NaNO2, may lead to unrealistic worst-case situations when the main form of NO2− in the drug product (DP) under evaluation may be NH4NO2. As well, measuring NO2− in freshly manufactured excipients containing NO2− potentially as NH4NO2 may lead to biased high NO2− content, which is not representative of the actual amounts present at the time of DP manufacture.

Crystallization Behavior and Crystallographic Properties of dl-Arabinose and dl-Xylose Diastereomer Sugars.

Natural sugar molecules such as xylose and arabinose exhibit sweetness profiles similar to sucrose, which makes them a valuable alternative in low-calorie foods as well as excipients or cocrystallization agents in pharmaceutical formulations. Xylose and arabinose are also chiral diastereomers that can exhibit specific crystallization behavior. In this work, the solid-state landscapes of the chiral pairs of both xylose and arabinose have been investigated to determine whether racemic compounds or conglomerates are formed. Furthermore, single crystals of xylose and arabinose have been grown and characterized by X-ray diffraction and optical microscopy to study their crystallographic properties and relate them to the crystallization behavior. Differential scanning calorimetry (DSC) measurements were used to determine the phase diagrams of the two analyzed chiral systems. The solubilities of the different solid forms of xylose and arabinose were measured in different solvent mixtures by a thermogravimetric method. An analysis was conducted to assess the main thermodynamic parameters and the activity coefficients of the compounds in solution. Finally, slurry experiments in a 50:50 w/w ethanol/water solvent have also been performed to determine the relative stability of each solid form and the kinetics of transformation in this solvent mixture. It was found that dl-arabinose crystallizes as a stable racemic compound, which transforms quickly from its constituent enantiomers when in solution; whereas d- and l-xylose molecules crystallize separately as a conglomerate.

Effects of pH and Electrolytes on Castor Oil Emulsions with Various Stabilisers Using Khaya senegalensis Gum as an Emulsifier.

Dispersed systems such as emulsions are easily destabilised during processing and storage since they are thermodynamically unstable systems. It is for this reason emulsifiers/stabilisers are frequently employed in pharmaceutical emulsion formulations to increase their short- and long-term kinetic stability. This current study seeks to investigate the potential emulsifying property of gums obtained from Khaya senegalensis (family: Meliaceae) trees. Gums were collected, authenticated, oven-dried, milled, filtered, and purified using 96% ethanol. The microbial quality of the gum was assessed following the BP (2013) specifications. The purified gum was free from some selected pathogenic microorganisms, rendering the gum safe for consumption. The emulsifying property was investigated by formulating emulsions using castor oil and employing the dry gum method. The ratios of oil-to-water-to-gum for the formulation of a stable emulsion were determined. The stability of the emulsion was evaluated, and an effort was made to improve the stability by incorporating Tween 80, hydroxypropyl methylcellulose, and xanthan gum. From the results, it can be inferred that Tween 80 (0.5%) was able to stabilise the emulsion. Addition of xanthan gum worsened the creaming. The effects of pH (4.0, 5.5, 7.2, 9.0, and 11.0) and electrolytes (0.1 M of NaCl, KCl, and CaCl2) on the physical stability of oil-in-water emulsions were studied during 12 weeks of storage. Percentage creaming volume and whether there was phase inversion were the criteria used as the evaluation parameter. From the percentage creaming volume data, emulsions formulated with both gums showed the lowest creaming volumes at pH of 7.2, followed by the acidic regions (pH 4.0, 5.5), with the basic regions (pH 9.0, 11.0) recording the highest creaming volumes. The effects of the various electrolytes at a constant concentration of 0.1 M on the o/w emulsions were found in this order NaCl < KCl < CaCl2. This study proves that Khaya senegalensis gum can successfully be employed as an emulsifying agent in pharmaceutical formulations.

Studies on Fruit Pectin in the Development of Tablet Formulations of Ibuprofen

Background: Pectin, a naturally occurring polysaccharide is more than a food additive and has got amazing properties as a gelling agent and as a binder.&#x0D; Objective: The current research entails the extraction and identification of pectin from peels of selected fruits mango (Magnifera indica) and banana (Musa paradisiaca) by direct heating and using alcohol as precipitating agent. The potential of pectin as a binding agent in tablet formulation was evaluated by screening its micromeritics and post compression properties.&#x0D; Method: quadruple formulations of ibuprofen with crude peel pectin extracted from mango and banana in concentration of 50, 75, 100 and 125 mg respectively were employed in the tablet manufacture process by wet granulation method.&#x0D; Results: Successful formulation of tablet was done with the extracted pectin from the two fruit peels. The micromeritics properties showed good binding and flowing properties. An increase in concentration of pectin increased the hardness and also the dissolution of tablets up to a certain extent. The disintegration time was suitable for all formulations.&#x0D; Conclusion: It was concluded that pectin extracted from mango and banana peels can be used as a super disintegrating agent in pharmaceutical formulations, where needed.

Eco-friendly micellar electrokinetic capillary chromatographic method for the simultaneous determination of newly developed antiviral agents in pharmaceutical formulations

A novel micellar electrokinetic capillary chromatographic (MEKC) method was developed for the simultaneous determination of ombitasvir (OMB), paritaprevir (PAR), ritonavir (RIT) and dasabuvir (DAS). The technique was based on the separation of all of the selected drugs in a deactivated fused silica capillary with a background electrolyte solution (BGE) composed of 25 mM phosphate buffer with 30 mM sodium dodecyl sulphate (SDS) (the pH of the aqueous phase was adjusted to 8) mixed with ethanol in a ratio of 65:35 (v/v). The capillary and sample temperature was maintained at 24 °C, and the detection was performed at 239 nm. The electrophoresis was performed by applying high voltage (30 kV) to the capillary. The strategy was completely approved according to ICH rules over the concentration range of 2.5 to 100 µg/mL for all of the drugs. The limits of detection were 0.16 µg/mL (PAR, DAS, and OMB) and 0.625 μg/mL (RIT), while the quantitation limits were 0.31 μg/mL (PAR, DAS, and OMB) and 1.250 μg/mL (RIT). The proposed MEKC method was successfully applied for the quantitation of the four drugs in tablets with high precision and accuracy. For the first time, these drugs were simultaneously determined by capillary electrophoresis.

Changes in membrane biophysical properties induced by the Budesonide/Hydroxypropyl-β-cyclodextrin complex

Budesonide (BUD), a poorly soluble anti-inflammatory drug, is used to treat patients suffering from asthma and COPD (Chronic Obstructive Pulmonary Disease). Hydroxypropyl-β-cyclodextrin (HPβCD), a biocompatible cyclodextrin known to interact with cholesterol, is used as a drug-solubilizing agent in pharmaceutical formulations. Budesonide administered as an inclusion complex within HPβCD (BUD:HPβCD) required a quarter of the nominal dose of the suspension formulation and significantly reduced neutrophil-induced inflammation in a COPD mouse model exceeding the effect of each molecule administered individually. This suggests the role of lipid domains enriched in cholesterol for inflammatory signaling activation.In this context, we investigated the effect of BUD:HPβCD on the biophysical properties of membrane lipids. On cellular models (A549, lung epithelial cells), BUD:HPβCD extracted cholesterol similarly to HPβCD. On large unilamellar vesicles (LUVs), by using the fluorescent probes diphenylhexatriene (DPH) and calcein, we demonstrated an increase in membrane fluidity and permeability induced by BUD:HPβCD in vesicles containing cholesterol. On giant unilamellar vesicles (GUVs) and lipid monolayers, BUD:HPβCD induced the disruption of cholesterol-enriched raft-like liquid ordered domains as well as changes in lipid packing and lipid desorption from the cholesterol monolayers, respectively. Except for membrane fluidity, all these effects were enhanced when HPβCD was complexed with budesonide as compared with HPβCD. Since cholesterol-enriched domains have been linked to membrane signaling including pathways involved in inflammation processes, we hypothesized the effects of BUD:HPβCD could be partly mediated by changes in the biophysical properties of cholesterol-enriched domains.

Simultaneous determination of newly developed antiviral agents in pharmaceutical formulations by HPLC-DAD

BackgroundOmbitasvir/paritaprevir/ritonavir/dasabuvir (Viekira Pak®) are the newest medicines approved for use in the treatment of hepatitis C virus (HCV) and are available in tablet form as an oral combination. Specifically, these agents are indicated in the treatment of HCV in patients with genotype 1 infection. Due to the therapeutic importance and increased use of Viekira Pak, proper methods for its determination in bulk and pharmaceutical formulations must be developed.ResultsThe present study describes the development and validation of a simple, rapid, selective and economical reverse phase high performance liquid chromatography-diode array detection (HPLC-DAD) method for the simultaneous determination of paritaprevir (PAR), ombitasvir (OMB), dasabuvir(DAS) and ritonavir (RIT) in bulk and pharmaceutical preparations. The proposed method was carried out using an RPC18 column (150 × 4.5 mm, 3.5 μ), with a mobile phase consisting of 10 mM phosphate buffer (pH 7)and acetonitrile (35:65, v/v) at a flow rate of 1 ml/min and a detection wavelength of 254 nm. Sorafenib (SOR) was selected as the internal standard to ensure that the quantitative performance was high. The method was validated based on its specificity, linearity, limit of detection, limit of quantitation, accuracy, precision, robustness and stability. The calibration curves for PAR, DAS, RIT and OMB were linear at 2.5–60, 1.25–30, 1.7–40 and 0.42–10 μg/ml, respectively, and all of the correlation coefficients were >0.999.ConclusionsThe proposed method was successfully applied for the determination of ombitasvir/paritaprevir/ritonavir/dasabuvirin tablets, without interference from the excipient peaks. Hence, the method can be applied for the routine quality control analysis of the studied drugs, either in bulk or dosed forms.Graphical abstractSimultaneous estimation of newly developed antiviral agents in pharmaceutical formulations by HPLC-DAD method

Novel serine-based gemini surfactants as chemical permeation enhancers of local anesthetics: A comprehensive study on structure–activity relationships, molecular dynamics and dermal delivery

This work aims at studying the efficacy of a series of novel biocompatible, serine-based surfactants as chemical permeation enhancers for two different local anesthetics, tetracaine and ropivacaine, combining an experimental and computational approach. The surfactants consist of gemini molecules structurally related, but with variations in headgroup charge (nonionic vs. cationic) and in the hydrocarbon chain lengths (main and spacer chains). In vitro permeation and molecular dynamics studies combined with cytotoxicity profiles were performed to investigate the permeation of both drugs, probe skin integrity, and rationalize the interactions at molecular level. Results show that these enhancers do not have significant deleterious effects on the skin structure and do not cause relevant changes on cell viability. Permeation across the skin is clearly improved using some of the selected serine-based gemini surfactants, namely the cationic ones with long alkyl chains and shorter spacer. This is noteworthy in the case of ropivacaine hydrochloride, which is not easily administered through the stratum corneum. Molecular dynamics results provide a mechanistic view of the surfactant action on lipid membranes that essentially corroborate the experimental observations. Overall, this study suggests the viability of these serine-based surfactants as suitable and promising delivery agents in pharmaceutical formulations.

Determination of iodinated X-ray contrast agents in pharmaceutical formulations and artificial urine samples by differential pulse voltammetry

This manuscript shows how to quickly detect the concentration of three iodinated X-ray contrast agents (iopromide, iodixanol and amidotrizoic acid) using differential pulse voltammetry.

Medical-grade collagen peptide in injectables provides antioxidant protection

Medical-grade collagen peptide is used as an additive agent in pharmaceutical formulations; however, it is unknown as to whether the compound exerts antioxidant effects in vitro. In this study, we evaluated the antioxidant effects of medical-grade collagen peptide on reactive oxygen species such as hydroxyl radical, superoxide anion radical and singlet oxygen using electron spin resonance and spin trapping. We confirmed that medical-grade collagen peptide directly inhibited hydroxyl radical generated by the Fenton reaction or by ultraviolet irradiation of hydrogen peroxide, and singlet oxygen. In addition, an antioxidant effect of medical-grade collagen peptide on singlet oxygen was observed in peptide fractions 12–22. The total amount of antioxidant amino acids (Gly, Hyp, Glu, Ala, Cys, Met and His) constituted more than half of the total amino acids in these fractions. These results suggest that the observed antioxidant properties of medical-grade collagen peptide are due to the compound containing antioxidant amino acids. Medical-grade collagen peptide, which is used in pharmaceuticals, and especially in injectables, could provide useful antioxidant properties to protect the active ingredient from oxidation.

Inhibitory Effects of Resveratrol Analogs on Mushroom Tyrosinase Activity

Skin pigmentation disorders typically involve an overproduction or uneven distribution of melanin, which results in skin spots. Resveratrol can inhibit tyrosinase, the active enzyme in the synthesis of melanin, but it does not inhibit the synthesis of melanin to an extent that enables its use alone as a skin whitening agent in pharmaceutical formulations, so its use as a coadjuvant in treatment of hyperpigmentation is suggested. Six resveratrol analogs were tested for tyrosinase inhibitory activity in vitro. Among the analogs tested, compound D was the most powerful tyrosinase inhibitor (IC50 = 28.66 µg/mL), two times more active than resveratrol (IC50 = 57.05 µg/mL), followed by the analogs A, E, B, F and C, respectively. This demonstrated that the hydroxylation at C4' on the phenolic ring was the molecular modification with most importance for the observed activity.

Characterisation of the interactive properties of microcrystalline cellulose–carboxymethyl cellulose hydrogels

Combinations of microcrystalline cellulose (MCC) and sodium carboxymethyl cellulose (Na-CMC) are commonly used as stabilising agents and suspending agents in pharmaceutical formulations. This paper is based on a study of the interactions that take place during the process of hydrogel formation, break down, and recovery. Also considered is the binding that occurs between the MCC and the Na-CMC. Avicel RC 591, a processed mixture of MCC and Na-CMC, is one of the more commonly used commercial suspending agents for aqueous compositions. Avicel RC 591 is used as an effective, blended stabilising agent. In this study, the contributions made by each of the components of Avicel RC 591 have been rationalised by monitoring the behaviour of the individual components in Avicel RC 591 suspensions or solutions. The hydrogels that are formed by Avicel RC 591 and by their laboratory formulated equivalent, which is spray dried (MCC + Na-CMC), have been characterised by confocal microscopy scanning electron microscopy and by dynamic light scattering. A 3D network structure that is formed by the MCC, in Avicel RC 591 is visualised. This network is supported by hydrogen bonding and by ionic interactions among and between the MCC, the Na-CMC and water. The strength of the network determines the physical properties of the hydrogel system, as seen in the rheological behaviour.

Chiral selectors for enantioresolution and quantitation of the antidepressant drug fluoxetine in pharmaceutical formulations by 19F NMR spectroscopic method

19F NMR spectroscopy was applied to the quantitative determination of fluoxetine enantiomers using different chiral recognition agents in pharmaceutical formulations. Several parameters affecting the enantioresolution including the type and concentration of chiral selector, concentration of fluoxetine and temperature were studied. The chiral selectors investigated are the cyclic oligosaccharides α-, β- and γ-cyclodextrin and a diamino derivative of methylated α-cyclodextrin (DAM-α-CD), linear polysaccharides (maltodextrin with dextrose equivalents of 4.0–7.0, 13.0–17.0 and 16.5–19.5) and the macrocyclic antibiotic vancomycin. Among the chiral selectors used, DAM-α-CD turned out to give the best resolution of the 19F NMR signals of ( R)- and ( S)-fluoxetine. The calibration curve was linear for ( R)- and ( S)-fluoxetine over the range 0.10–1.35 mg mL −1, the detection limits (S/N = 3) being 5.9 and 7.5 μg mL −1 for the pure solutions of ( R)- and ( S)-fluoxetine, respectively. The recovery studies performed on pharmaceutical samples ranged from about 90 to 110% with relative standard deviations of <8%. The results showed that the proposed method is rapid, precise and accurate. Applying statistical Student's t-test revealed insignificant difference between the real and measured contents at the 95% confidence level.

A RP-LC method with evaporative light scattering detection for the assay of simethicone in pharmaceutical formulations

A reversed-phase liquid chromatographic method has been developed and validated for the determination of the polydimethylsiloxane (PDMS) component of Simethicone, which is used as an anti-foaming agent in pharmaceutical formulations. The method involves acidification to neutralise antacid components of the formulation, then a single extraction of the PDMS with dichloromethane. This is followed by separation with a reversed-phase column using an acetonitrile–chloroform solvent gradient, and quantification by an evaporative light scattering detector. An assay precision of 3% was achieved in intraday and interday determinations. No interference was found from the aluminium and magnesium hydroxide components of antacid formulations.

Spectrophotometric determination of β-adrenergic blocking agents in pharmaceutical formulations

Simple, rapid and sensitive spectrophotometric procedures were developed for the analysis of atenolol, timolol maleate, propranolol hydrochloride, metoprolol tartarate, betaxolol hydrochloride, levobunolol hydrochloride and bisprolol fumarate in pure form as well as in their pharmaceutical formulations. The methods are based on the reaction of these drugs as n-electron donors with the sigma-acceptor iodine, and the pi-acceptors: 7,7,8,8-tetracyanoquinodimethane, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, tetracyanoethylene, 2,3,5,6-tetrabromo-1,4-benzoquinone (bromanil) and 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil). The obtained charge-transfer complexes were measured at 365 nm for iodine (in 1,2-dichloroethane), at 840, 420, and 470 nm for 7,7,8,8-tetracyan-oquinodimethane, tetracyanoethylene and 2,3-di-chloro-5,6-dicyano-1,4-benzoquinone (in acetonitrile), respectively, and at 450 and 440 nm for bromanil and chloranil (in ethanol), respectively. Due to the rapid development of colors at ambient temperature, the obtained results were used on thin-layer chromatograms for the detection of the investigated drugs. Beer's plots were obeyed in a general concentration range of 4-120 microg ml(-1) with correlation coefficients not less than 0.9991. The proposed procedures could be applied successfully to the determination of the investigated drugs in tablets and ophthalmic solutions with good recovery; percent ranged from 98.03+/-0.98 to 100.30+/-0.90. The association constants and standard free energy changes using Benesi-Hildebrand plots were studied.

SPECTROPHOTOMETRIC DETERMINATION OF SOME LOCAL-ANAESTHETICS BY USING PICRYL-CHLORIDE AND CHLORANILIC ACID

Two simple and sensitive spectrophotometric methods are described for the determination of ten local anaesthetics. The first one was based on measuring of coloured products resulting from using picryl chloride as a derivatlzaiion reagent for the quantification of the drugs. The cited reagent reacts with the amino group of local anaesthetic in acetone using anhydrous potassium carbonate as hydrochloride acceptor. The reaction was completed within 2 minutes on hot water-bath at 6(1°. The coloured products are quantified spectrophotometrically and exhibit two main absorption bands (370-375 nm) and (410-450 nm). The position of x._ differ according to the structure of the drug. The second method was based on the interaction of the drug and p-chloranillc acid to yield stable and intensively coloured ion-pair salt. The reddish violet chromogen formed was measured at 525 nm. Beer's law was obeyed in range form 2.5- 20 µ.glmlfor the first method and from 10-100 µglmlfor the second one. The optimization of the different experimental conditions is described. Applications of the suggested methods to representative pharmaceutical dosage forms are presented and compared with official methods with good accuracy and precision. The recoveries ranged from 98±1 to 100±0.6. Interferences from the commonly present additives or agents in pharmaceutical formulations were investigated. The proposed methods were found rapid and selective. The selectivity and specificity of plcryl-chloride method is exhibited by the different position of maximum wavelength and can differentiate between the investigated drugs.

Simultaneous determination of the beta-blocker atenolol and several complementary antihypertensive agents in pharmaceutical formulations and urine by capillary zone electrophoresis.

A simple capillary zone electrophoresis method is developed for the quantitation of the beta-blocker atenolol and the complementary antihypertensive agents bendroflumethiazide, amiloride, and hydrochlorothiazide in human urine samples. The electrophoretic separation is performed using a 78-cm x 75-micron-i.d. (70-cm effective length) fused-silica capillary. A borate buffer (pH 9) is used as running electrolyte. The sample is hydrostatically introduced for 20 s, and the running voltage is 25 kV at the injector end of the capillary. The analysis of urine samples requires the optimization of solid-phase extraction methods, achieving recoveries > or = 61% for all the drugs and good separation from the urine matrix. The method is successfully applied to the determination of these compounds in pharmaceutical formulations and in urine samples collected after the intake of Neatenol Diu (100 mg atenolol-5 mg bendroflumethiazide) and Kalten (50 mg atenolol-25 mg hydrochlorothiazide-2.5 mg amiloride). The method is validated in terms of reproducibility, linearity, and accuracy.

Aggregation of recombinant human growth hormone induced by phenolic compounds

Phenolic compounds can be used as antimicrobial preservative agents in pharmaceutical formulations. Unfortunately, these compounds often adversely affect proteins, triggering aggregation in particular. In this study, a variety of phenolic compounds and structurally similar non-aromatic alcohols were investigated for their role in causing the aggregation of a model therapeutic protein, recombinant human growth hormone (rhGH). As determined by various methodologies, most of the phenolic compounds caused rhGH aggregation, especially at high concentrations. Stress studies under freezing, high-temperature incubation, and agitation suggest that the destabilizing influence of the compounds tested increases in the order of benzyl alcohol < phenol × resorcinol < catechol < meta-cresol < 2-chlorophenol. Non-aromatic alcohols, except 2,6-dimethylcyclohexanol, have a much less adverse effect. Determination of the thermal transition temperature by microcalorimetry studies also reflected this trend. From our study, we conclude: (1) the phenolic additive-induced rhGH aggregates were held by non-covalent forces; (2) no significant physical binding occurred between the protein and these compounds; (3) the aggregation tendency of the phenolic compounds failed to correlate with their hydrogen bonding strength; (4) the presence of a phenolic additive caused conformational changes in rhGH's structure; (5) the effect of these phenolic compounds on rhGH aggregation decreased at high and low pHs.