In vitro and in vivo investigation of taste-masking effectiveness of Eudragit E PO as drug particle coating agent in orally disintegrating tablets

Spray drying Eudragit® E-PO with acetaminophen using 2- and 3-fluid nozzles for taste masking

Conventional spray drying using a 2-fluid nozzle forms matrix microparticles, where drug is distributed throughout the particle and may not effectively mask taste. In contrast, spray drying using a 3-fluid nozzle has been reported to encapsulate material. The objective of this study was to spray dry Eudragit® E-PO (EE) with acetaminophen (APAP), a water-soluble model drug with a bitter taste, using 2- and 3-fluid nozzles for taste masking. Spray drying EE with APAP, however, resulted in yields of ≤ 13 %, irrespective of nozzle configuration. Yields improved when Eudragit® L 100-55 (EL) or Methocel® E6 (HPMC) was used in the inner fluid stream of the 3-fluid nozzle or in place of EE for the 2-fluid nozzle. Drug release from microparticles prepared with the 2-fluid nozzle was relatively rapid. Using EE in the outer fluid stream of the 3-fluid nozzle resulted in comparatively slower drug release, although drug release was observed, indicating that encapsulation was incomplete. Results from these studies also show that miscible polymers used in the two fluid streams mix during the spray drying process. In addition, findings from this study indicate that the polymer used in the inner fluid stream can impact drug release.

Taste-masking methods in multiparticulate dosage forms with a focus on poorly soluble drugs

In the past, the administration of medicines for children mainly involved changes to adult dosage forms, such as crushing tablets or opening capsules. However, these methods often led to inconsistent dosing, resulting in under- or overdosing. To address this problem and promote adherence, numerous initiatives, and regulatory frameworks have been developed to develop more child-friendly dosage forms. In recent years, multiparticulate dosage forms such as mini-tablets, pellets, and granules have gained popularity. However, a major challenge that persists is effectively masking the bitter taste of drugs in such formulations. This review therefore provides a brief overview of the current state of the art in taste masking techniques, with a particular focus on taste masking by film coating. Methods for evaluating the effectiveness of taste masking are also discussed and commented on. Another important issue that arises frequently in this area is achieving sufficient dissolution of poorly water-soluble drugs. Since the simultaneous combination of sufficient dissolution and taste masking is particularly challenging, the second objective of this review is to provide a critical summary of studies dealing with multiparticulate formulations that are tackling both of these issues.

Solvent-free method for masking the bitter taste of azithromycin dihydrate using supercritical fluid technology

INTRODUCTION AND PURPOSE

The unpleasant extremely bitter taste of the orally administered broad-spectrum antibiotic azithromycin decreases patient compliance, especially in pediatrics. This issue can be overcome by decreasing drug interaction with the tasting buds using insoluble polymers at salivary pH (6.8 - 7.4), like the cationic polymer Eudragit EPO. Supercritical fluid technology is a green synthesis method for preparing pharmaceutical preparations that replace organic solvents with safe supercritical CO2. This study aimed to mask the bitter taste of azithromycin using the supercritical fluid method and a pH-sensitive Eudragit EPO polymer.

METHODS

A foaming process was investigated for preparing a formulation (TEST), which comprises treating the polymer with supercritical carbon dioxide (CO2) fluid to prepare a taste-masked dosage form without employing organic solvents or flavors.

RESULTS

The use of the supercritical technique at 40 °C and 10 MPa for 2 h allowed the manufacturing of solvent-free polymeric foam with azithromycin dispersions; the average calculated percentage of apparent volume change was 62.5 ± 5.9% with an average pore diameter of 34.879 Å. The formulated sample showed low drug release in simulated salivary fluid while keeping its crystalline nature. Moreover, clinical studies on healthy subjects showed that the formula successfully masked azithromycin's bitter taste.

CONCLUSIONS

Overall, it has been shown herein that the supercritical fluid technology foaming method is promising in masking the bitter taste of bitter ingredients.

Development of taste masking microcapsules containing azithromycin by fluid bed coating for powder for suspension and in vivo evaluation

This research aims to develop bitter taste masking microcapsules containing azithromycin by a simpler and familiar method, fluid-bed coating technology, in comparison with Zithromax®. Cores of microcapsules, azithromycin microparticles, were prepared by fluid-bed granulation, then taste-masking polymer was covered on by fluid-bed coating technique. Eudragit L100, Eudragit RL100, ethyl cellulose in single and combined with Eudragit L100, Eudragit E100 were used as taste-masking polymers. The obtained microcapsules were characterized by taste masking ability, in-vitro release, SEM, coating thickness and coating efficiency. Combination of ethyl cellulose and Eudragit E100 (3:1) in coating thickness of 45.13 ± 2.12% w/w prevent azithromycin release from microcapsules below bitter taste threshold (1.78 ± 1.17 μg/ml). Bioavailability of powders containing azithromycin microcapsules and pH modulators (50mg Na₃PO₄ and 35mg Mg(OH)₂) was not significantly different from the reference product (Zithromax®, Pfizer) in the rabbit model (p > 0.05). These results support the possibility of developing a generic product containing azithromycin.

Role of Nanotechnology in Taste Masking: Recent Updates

One of the important parameters in the case of dosage form is taste. Most of the drugs available in oral dosage form have an unpleasant taste which leads to patient incompliance and affects the success ratio of products in the market. Geriatric and paediatric patients suffer more with the bitter taste of medicines. According to the studies reported, it is found that 50% of the population have the problem swallowing tablets, especially the pediatric and geriatric population. Masking the taste of bitter drugs has become necessary in the pharmaceutical field and increasing interest of researchers to develop various methods for masking the bitter taste of drugs. Five major tastes, felt by our tongue are salt, sour, sweet, bitter, and umami. When the drug dissolves with saliva, drug molecules interact with taste receptors present on the tongue and give taste sensations. Although, many solid oral dosage forms like pills, and tablets have an additional advantage of masking and encapsulation of bitter taste drugs; however, they might not be effective for children because they may or may not swallow pills or tablets. There are various other methods that mask the bitter taste of drugs such as the addition of sweeteners and flavouring agents, granulation, coating, inclusion complexes, extrusion method, ion-exchange resins, etc, discussed in the first section of the article. The second part of this article consists of various nanotechnology-based drug delivery systems that were fabricated by researchers to mask the bitter taste of drugs. A brief of recent literature on various nanocarriers that were fabricated or developed for taste masking has been discussed in this part. A better understanding of these methods will help researchers and pharmaceutical industries to develop novel drug delivery systems with improved taste masking properties.

Study on the taste-masking effect and mechanism of Acesulfame K on berberine hydrochloride

OBJECTIVE

In our previous taste-masking study, we found that Acesulfame K (AK) had a better taste-masking effect than other high-efficiency sweeteners for several representative bitter natural drugs in aqueous decoction. Furthermore, we performed a preliminary taste-masking study of AK for representative bitter API Berberine Hydrochloride (BH) and found that it had a good taste-masking effect. We also found that flocculent precipitation was generated in the BH solution, but it was not clear whether it was related to the good taste-masking effect. This study was conducted to explore the taste-masking effect and mechanism of AK on BH.

METHODS

The taste-masking effect of AK on BH was evaluated based on the Traditional Human Taste Panel Method and the electronic tongue evaluation method. DSC, XRD, and molecular simulation techniques were used to explore the mechanism of AK on BH, from the macro level and molecular level, respectively.

RESULTS

When evaluating the taste-masking effect, we found that 0.1% AK had the best taste-masking effect on BH, while higher concentrations had a worse taste-masking effect. DSC and XRD revealed that the flocculent precipitation was a complex AK-BH. Finally, by simulating the binding of AK, BH, and TAS2R46 receptors, we found the unique taste-masking mechanism of AK.

CONCLUSION

The sweet taste stimulus of AK can mask the bitter taste stimulus of BH, and AK can generate AK-BH with BH to reduce the contact between BH and bitter taste receptors. Additionally, it could block the expression of the TAS2R46 receptors.

Preference, Perception, and Acceptability of Fluid Gels as a Potential Age-Appropriate Dosage Form for Elderly Patients with Dysphagia

The development of pharmaceutical dosage forms that are tailored to specific populations according to their preferences and acceptability could improve medication adherence, which could lead to effective pharmacotherapy. This study evaluated the preference for and perceptions of fluid gels as a potential age-appropriate dosage form for older adults with dysphagia. The palatability and swallowability of the developed fluid gels were also assessed to determine the consumer acceptability of this formulation. A cross-sectional survey was conducted through the electronic distribution of a self-administered questionnaire among adults in Malaysia between April and December 2021. A randomized and double-blinded clinical study was conducted to evaluate the palatability and swallowability of the fluid gels in 30 healthy participants. A cross-sectional study involving 673 respondents revealed that the fluid gels were perceived positively by consumers (64.4%), were easily swallowed (50.8%), were safe to be consumed (45.3%), and were suitable as a new pharmaceutical formulation (43.8%). The clinical study shows that moderately thickened fluid gels masked the bitterness of the medication and were easily swallowed. The newly developed fluid gels were also positively perceived by the participants. Taken together, fluid gels have shown great potential as an innovative oral formulation that is suitable for consumption by elderly patients with dysphagia.

Effect of plasticizers on drug-in-adhesive patches containing 5-fluorouracil

Topical patches containing 5-fluorouracil (5-FU) are a feasible alternative to overcome the shortcomings of commercial cream for the treatment of non-melanoma skin cancer (NMSC). Plasticizers are a critical component of drug-in-adhesive (DIA) patches as they can significantly affect the mechanical, adhesive and drug release characteristics of the patches. Eudragit® E (EuE) is a methacrylate-based cationic copolymer capable of producing flexible and adhesive films for topical application. In this study, the effect of plasticizers on the mechanical, adhesive and 5-FU release characteristics of EuE-based patches was comprehensively evaluated. While the elongation at break (%) and adhesion of the films were significantly increased with increasing triacetin, dibutyl sebacate (DBS) and triethyl citrate (TEC) concentrations, the tensile strength showed an inverse relationship. EuE plasticized with 40% triacetin, 30% DBS or 40% w/w TEC produced elastic and adhesive films most suitable for topical application. In vitro release studies of the 5-FU-loaded patches demonstrated an initial burst release pattern during the first 10 min followed by a slow release over 120 min. In summary, this study provides important information on effect of plasticizers for preparation of EuE-based patches with desired mechanical, adhesive and release characteristics of 5-FU towards their potential application in the treatment of NMSC.

On the feasibility of spray-dried eudragit-trehalose microparticles for enteric drug delivery

Enteric infections have long constituted a silent epidemic responsible for hundreds of thousands of deaths around the world every year. Because of the global rise in antibiotic-resistant bacteria and the slow development of new small-molecule antibiotics, alternatives such as bacteriophage therapy have become a much sought-after option in the treatment of enteric infections. However, the administration of therapeutics through the oral route to target gastrointestinal infections poses challenges to dosage formulation because these active ingredients, particularly relatively fragile biological entities, require protection from the stomach's harsh acids. Encapsulation of the therapeutics within a pH-responsive coating capable of surviving low pH conditions has the potential to provide such protection. In this study, we developed a spray-dried powder vehicle capable of withstanding low pH comparable to stomach conditions, using Eudragit® S100 as a protective particle coating and trehalose as a stabilizing excipient for a possible active component. A particle formation model and a monodisperse droplet chain technique were initially used to study the formation process of Eudragit-trehalose composite microparticles at different ratios and in different ratios of water-ethanol solvent, which showed formation of particles with Eudragit shells varying in thickness from 0.13 μm to 0.75 μm. Promising Eudragit-trehalose formulations were subsequently spray-dried and their survival in acidic and alkaline environments studied using a new shadowgraphic imaging method. The results demonstrated that Eudragit was capable of creating a protective shell in the particles irrespective of the type of solvent used to prepare the formulations. The trehalose cores of particles with higher than 5% w/w of Eudragit remained protected after one hour of exposure at pH 2, indicating the potential of Eudragit-trehalose formulations for enteric delivery of drugs.

Orodispersible tablets for pediatric drug delivery: current challenges and recent advances

INTRODUCTION

Child appropriate dosage forms are indispensable in modern medicine and are a prerequisite for successful pediatric drug therapy. For years, experts have called for a paradigm shift, from liquid dosage forms to novel oral solid dosage forms. This review aims to shed light on recent developments in Orodispersible tablets (ODTs) and mini-tablets (ODMTs).

AREAS COVERED

This review focuses on the presentation and critical discussion of current challenges as well as recent advances in ODTs for pediatric drug delivery. Highlighted aspects are the evidence for acceptability by children, e.g. in comparison to other dosage forms, and limitations given by tablet size at different ages, as well as advances in special ODT formulations (taste masking, modified release, enabling formulations).

EXPERT OPINION

It is the authors' belief that OD(M)Ts have significant potential as dosage forms in pediatric therapy that has not yet been fully exploited. The reasons for this are, first, that the number of direct acceptance studies is extremely low and the resulting knowledge is therefore rather anecdotal. Despite the high relevance, there seems to be reluctance both in the therapeutic use and conduction of respective studies in children. However, if one combines the knowledge from the few existing studies, surveys, and from approved products, it becomes apparent that so far there is no evidence on limitations of the use of ODTs in pediatric patients.

Preparation and characterization of aqueous vitamin E/Soluplus® dispersions for film coating applications

OBJECTIVE

The goals of this study were to (1) delineate a technique to prepare stable aqueous vitamin E/Soluplus® dispersions; (2) characterize films cast from the aqueous dispersions; and (3) demonstrate the utility of the aqueous dispersions in fluid bed coating applications. This study demonstrated the feasibility of using vitamin E in the preparation of amphiphilic film withs potential use in delayed-release coating applications.

METHODS

Low viscosity aqueous vitamin E/Soluplus® dispersions were prepared by first spray drying ethanolic vitamin E/Soluplus® solutions followed by high-shear homogenization of the solid dispersions in water. Concentrated (10%) aqueous dispersions containing 0%, 10%, 20%, and 30% of vitamin E in the binary blend with Soluplus® were then cast into films and characterized for contact angle and mechanical strength by texture analysis.

RESULTS

All films were hydrophilic and homogenous, which confirmed the utility of vitamin E as a plasticizer for the Soluplus® polymer. The 0% and 10% films were brittle whereas the 30% were tacky. The 20% dispersion was subsequently used to coat acetaminophen granules by a fluidized bed process to a dry weight gain of 10-30%. When tested by a dissolution study, a delay in acetaminophen release was observed as a function of weight gain.

CONCLUSION

The results from this study demonstrated that it is feasible to produce stable vitamin E/Soluplus® aqueous dispersions to be used as solvent-free functional film coating materials.

Formulation and evaluation of bitter taste-masked orally disintegrating tablets of high memantine hydrochloride loaded granules coated with polymer via layering technique

Orally disintegrating tablets (ODTs) improve patient adherence as they can easily disintegrate in the presence of small amount of saliva. However, the bitter taste of the active pharmaceutical ingredient in ODTs reduces patient compliance. The present study aimed to formulate bitter taste-masked ODTs containing high-dose of memantine hydrochloride (MTN) to achieve a balance between bitterness suppression and dissolution rate or disintegration time and mechanical strength. The high MTN-loaded granules were prepared using a fluidized bed granulator. Taste-masking granules coated with the selected polymer were prepared using the layering technique. Three ODTs, composed of granules coated with different polymers, were prepared. The ODT prepared using granules coated with enteric polymers showed the fastest collapse time (>20 s). Dissolution rates of ODTs composed of enteric polymers were reduced by 5 min compared with ODTs composed of non-coated or coated with water-insoluble polymer granules. X-ray computed tomography analysis revealed that low density distribution of ODTs with enteric polymer granules may result in faster disintegration time. Although ODT prepared using enteric polymers had the fastest collapse time, its change in membrane potential caused by adsorption (CPA), corresponding to aftertaste, was the lowest among formulations. This CPA value was lower than the bitterness threshold.

Development of nanoparticle-based orodispersible palatable pediatric formulations

Despite a collaborative effort towards developing suitable oral drug products for pediatrics over the past decade, appropriate pediatric dosage forms have remained lacking due to special considerations in dose flexibility, swallowability, palatability, and safety of excipients for pediatrics. The present research aims to develop a nanoparticle-based orodispersible pediatric drug delivery platform to improve oral bioavailability and taste of poorly water-soluble and unpalatable therapeutics. Two Biopharmaceutics Classification System II/IV compounds lopinavir (LPV) and ritonavir (RTV) with unpleasant taste were chosen as the model compounds. LPV and RTV Eudragit® E PO nanoparticles (NP) were prepared using a nanoprecipitation method and their key quality attributes and taste-masking effect were evaluated. Moreover, in vitro dissolution testing was conducted at simulated gastrointestinal pH conditions. The in vivo bioavailability of the developed NP formulations was assessed using a rat model. Following the formulation optimization, over 98% encapsulation efficiency was obtained for both LPV and RTV NP and both drugs remained amorphous in its respective NP. LPV/RTV NP combination (4/1, w/w) showed comparable in vitro dissolution to that of the commercial LPV/RTV tablet (Kaletra®). In addition, the taste-masking effect of the developed NP formulations was confirmed by an E-tongue study. The lyophilized LPV and RTV NP were completely dispersible in water within 7 sec and remained stable at 4 ± 2 °C over three months. Lastly, the pharmacokinetic study demonstrated that the LPV/RTV NP combination (4/1, w/w) had improved oral bioavailability compared to Kaletra® and their corresponding raw drug powders. The results demonstrated a novel nanoparticle-based orodispersible platform that is capable of improving oral bioavailability and taste of poorly water-soluble and unpalatable therapeutics for pediatric use.

Assessment of hot-melt coating methods for multiparticulate substrates: Mortar-coating vs. pan-coating

Hot-melt coating (HMC) is an alternative, solvent-free coating method generally used to modify substrate release rate and/or mask its unpleasant taste. The aim of this study was to assess two HMC methods (pan-coating and mortar-coating) by assaying functional properties of the coated material. The selected substrates included highly soluble sodium chloride (model substance) and caffeine (bitter drug), and the coating agent was glycerol distearate without/with the addition of liquid paraffin. Experiments with sodium chloride revealed that pan-coating yielded particles of more regular shape, while mortar-coating yielded samples of more uniform coating layer. The flowability of the coated material depended on the particle size. Sustained sodium chloride release was achieved for all mortar-coated and some pan-coated samples. The analysis of the results indicated mortar-coating as a preferable HMC method for caffeine coating. The resulting caffeine yield in the coated samples was high (99%), the material showed satisfactory mechanical properties and drug release from the coated particles was sustained. Overall, the obtained results suggest that both pan-and mortar-coating can be used to sustain the release of drugs with unpleasant taste, but mortar-coating can be considered as a more simple and practical method that can be potentially used in compounding pharmacies.

Evaluation of Cytotoxicity and Taste-Masking Effect of Selected Flavors on Dental Lidocaine HCl Injection

AIM

Anxiety and intolerance to dental local anesthetic injections are common in patients undergoing dental procedures. This work was designed to study cytotoxicity of selected flavors in primary gingival keratinocytes (PGK), to acquire information on their suitability for use in dental lidocaine hydrochloride (LID) injection. We also evaluated the bio-mimetic taste of LID dental injection in the presence of selected flavors and sweetener using an Astree electronic tongue (ETongue).

METHODS

The cytotoxicity of chocolate natural and artificial flavor (CTE), raspberry flavor artificial (RAS), cherry flavor (CHR), bitterness suppressor flavor (BSF) and lemon flavor extract (LFE) at various dilutions (0.16-10% v/v) was carried out in PGK using the live cell morphological analysis and MTT cell cytotoxicity assay. Based on the cytotoxicity data, CTE and RAS were added to Xylocaine^® (2%) along with 0.09% sodium saccharin and taste was assessed using an ETongue.

RESULTS

After three hours of treatment, a dose-dependent cell death was induced by all flavors compared to the untreated control. BSF was found to be more toxic when compared to other flavors. CTE was found to be less toxic. The mean IC50 values of CTE, RAS, CHR, BSF and LFE in PGK were found to be 9.54, 8.43, 2.21, 0.38 and 4.01 mg/mL. Taste analysis with the ETongue showed a clear taste difference between the control and test formulations containing CTE and RAS flavors along with sodium saccharin.

CONCLUSION

CTE and RAS flavors in combination with 0.09% sodium saccharin can achieve a significant taste-masking effect in the dental LID injection.

Characterization of the buccal and gastric transit of orally disintegrating tablets in humans using gamma scintigraphy

The present study characterized the buccal cavity-emptying and gastric-emptying kinetics of orally disintegrating tablets (ODTs) in fasted humans using gamma scintigraphy. ¹¹¹Indium-diethylenetriaminepentaacetic acid and technetium-99 m-labeled ion exchange resin were used as a model soluble drug and insoluble pellet-type drug, respectively, and housed in ODTs. These ODTs were then administered to human subjects with or without ingestion of water, after which scintigraphic images were collected in order to characterize the buccal and gastric transit of the radioactivity. The oral disintegration of the ODTs was extremely rapid, with a mean time of ≤1 min. The buccal emptying of the radioactivity was most rapid for the ODT with a water-soluble radiolabel; however, the ODTs with water-insoluble radiolabels showed buccal emptying with median half-times of ≤2.5 min. The ODT with the soluble radiolabel in subjects without water ingestion showed the most rapid gastric emptying compared with the ODTs with the insoluble radiolabels, the gastric-emptying time of which was highly variable. Further, water ingestion did not markedly affect the gastric-emptying time of the tablets with the water-soluble model drug. The observations in the present clinical study will help clarify the in vivo performance of ODTs in humans.

Selective Laser Sintering 3D Printing of Orally Disintegrating Printlets Containing Ondansetron

The aim of this work was to explore the feasibility of using selective laser sintering (SLS) 3D printing (3DP) to fabricate orodispersable printlets (ODPs) containing ondansetron. Ondansetron was first incorporated into drug-cyclodextrin complexes and then combined with the filler mannitol. Two 3D printed formulations with different levels of mannitol were prepared and tested, and a commercial ondansetron orally disintegrating tablet (ODT) product (Vonau^® Flash) was also investigated for comparison. Both 3D printed formulations disintegrated at ~15 s and released more than 90% of the drug within 5 min independent of the mannitol content; these results were comparable to those obtained with the commercial product. This work demonstrates the potential of SLS 3DP to fabricate orodispersible printlets with characteristics similar to a commercial ODT, but with the added benefit of using a manufacturing technology able to prepare medicines individualized to the patient.

Developments in Taste-Masking Techniques for Traditional Chinese Medicines

A variety of pharmacologically active substances, including chemotherapeutic drugs and the substances from traditional Chinese medicine (TCM), always exhibit potent bioactivities after oral administration. However, their unpleasant taste (such as bitterness) and/or odor always decrease patient compliance and thus compromise their curative efficacies in clinical application. Therefore, the developments of taste-masking techniques are of great significance in improving their organoleptic properties. However, though a variety of taste-masking techniques have been successfully used to mask the unpalatable taste of chemotherapeutic drugs, their suitability for TCM substances is relatively limited. This is mainly due to the fact that the bitter ingredients existing in multicomponent TCM systems (i.e., effective fractions, single Chinese herbs, and compound preparations) are always unclear, and thus, there is lack of tailor-made taste-masking techniques to be utilized to conceal their unpleasant taste. The relevant studies are also relatively limited. As a whole, three types of taste-masking techniques are generally applied to TCM, including (i) functional masking via sweeteners, bitter blockers, and taste modifiers; (ii) physical masking via polymer film-coating or lipid barrier systems; and (iii) biochemical masking via intermolecular interaction, β-cyclodextrin inclusion, or ion-exchange resins. This review fully summarizes the results reported in this field with the purpose of providing an informative reference for relevant readers.

A novel quantified bitterness evaluation model for traditional Chinese herbs based on an animal ethology principle

Traditional Chinese herbs (TCH) are currently gaining attention in disease prevention and health care plans. However, their general bitter taste hinders their use. Despite the development of a variety of taste evaluation methods, it is still a major challenge to establish a quantitative detection technique that is objective, authentic and sensitive. Based on the two-bottle preference test (TBP), we proposed a novel quantitative strategy using a standardized animal test and a unified quantitative benchmark. To reduce the difference of results, the methodology of TBP was optimized. The relationship between the concentration of quinine and animal preference index (PI) was obtained. Then the PI of TCH was measured through TBP, and bitterness results were converted into a unified numerical system using the relationship of concentration and PI. To verify the authenticity and sensitivity of quantified results, human sensory testing and electronic tongue testing were applied. The quantified results showed a good discrimination ability. For example, the bitterness of Coptidis Rhizoma was equal to 0.0579 mg/mL quinine, and Nelumbinis Folium was equal to 0.0001 mg/mL. The validation results proved that the new assessment method for TCH was objective and reliable. In conclusion, this study provides an option for the quantification of bitterness and the evaluation of taste masking effects.