Gamma Scintigraphy Research Articles

Physiologically active hydrogel (in situ gel) of sparfloxacin and its evaluation for ocular retention using gamma scintigraphy.

Objective:Due to the structure and physiological barrier of eye, only 1% of instilled dose is available for action on the corneal surface. In this work, we developed and evaluated chitosan (pH sensitive) and gellan gum (ion sensitive) in situ gel of sparfloxacin to improve precorneal residence time.Materials and Methods:A protocol for radiolabeling of sparfloxacin with Tc-99m was optimized to study the ocular retention using gamma scintigraphy technique.Results:The clear formulation was developed. In vitro release showed a sustained and prolonged release compared to plain eye drop solution. Dynamic and static gamma scintigraphy showed better retention than plain eye drops. The ocular tolerance test (hen's egg test-chorioallantoic membrane test and infra-red study) showed that the formulation is nonirritant and can be used as ocular vehicle.Conclusion:Radiolabel protocol for sparfloxacin was successfully developed and evaluated on ocular retention studies of developed in situ gel. The developed in situ gel is non irritant and can go further with clinical evaluation.

An alternative in situ gel-formulation of levofloxacin eye drops for prolong ocular retention.

Introduction:Delivering drugs to ocular region is a challenging task. Eye physiological barriers lead to relatively less therapeutic and bioavailability effect by the conventional eye drops. This may be overcome by the use of in situ gel delivery system.Objective:The objective of our work was to formulate an ocular delivery system of levofloxacin, based on the concept of ion (sodium alginate) and pH (chitosan) activated in situ gelation concept. Due to its elastic properties, in situ gels resist the ocular drainage of drug leading to longer contact times with ocular surface.Materials and Methods:The formulation was evaluated for physicochemical characteristics, in vitro drug release. Ocular retention studies were carried out by Gamma scintigraphy. Time activity curve was plotted between marketed formulation and developed formulation for comparing drug drainage from the eye with time. Ocular tolerance test was performed by handheld infra-red camera.Results and Discussion:The formulations showed a first-order release pattern over 12 h. Both in vitro release studies and in vivo gamma scintigraphy precorneal retention studies indicated better therapeutic efficacy compared with standard eye drops.Conclusion:The results demonstrated that the developed in situ gel of levofloxacin is nonirritant, has prolonged action and is a better option in terms of retention, ocular bioavailability and patient compliance when compared with plain eye drops formulation.

Heterogeneity of Particle Deposition by Pixel Analysis of 2D Gamma Scintigraphy Images

Heterogeneity of Particle Deposition by Pixel Analysis of 2D Gamma Scintigraphy Images

Researching the dose ratio in a controlled release multiple-drug delivery system: using combination therapy with porous microparticles for the treatment of Helicobacter pylori infection.

Combination therapy can improve therapeutic efficacy or reduce side effects due to the synergistic effects between drugs, and the dose ratio, which is a key factor for combination therapy in the clinic, however, had not been considered in previous studies. Therefore, triple-drug-loaded porous microparticles (containing amoxicillin sodium, metronidazole, and omeprazole) were prepared by emulsion electrospray according to an experiential regimen for the combination therapy of Helicobacter pylori (H. pylori) infection, and the feeding mass ratios of the drugs were optimized to ensure that the mass ratios of released drugs are in accordance with the dose ratios of three drugs in the recommended regimen. In addition, the particle sizes were less than 10 μm, and the in vivo gamma scintigraphy study demonstrated that the 131I-labeled porous microparticles were retained in the stomach for more than 8 h. Furthermore, the triple-drug-loaded porous microparticles exhibited a stronger effect on H. pylori eradication compared to the free drugs. The results indicate that adjustment of the feeding amounts of drugs is an effective approach for the control of the amounts of drugs released from the diffusion-dependent multiple-drug delivery system. Moreover, the prepared triple-drug-loaded porous microparticles are more suitable for the treatment of clinical H. pylori infection.

Pharmacokinetic and biodistribution study of eserine and pralidoxime chloride in rabbits following a single application of a transdermal patch.

In the present study, a simple reverse-phase high-performance liquid chromatography method with diode array detection has been developed and validated for the simultaneous determination and quantification of eserine and pralidoxime chloride in rabbit plasma and its application to pharmacokinetic study. The pharmacokinetic study was performed after transdermal application of single patch in rabbits. The plasma levels of both drugs following transdermal application of single patch were maintained for 72h after removal of the patch. The maximal concentrations (C max) of both drugs were significantly reduced while the mean areas under the plasma concentration vs. time moment curve and mean residence times were evidently increased and extended, respectively. A sustained activity was observed over a period of 3days. This sustained activity was due to the controlled release of drug into the systemic circulation following transdermal application. Linear correlation was also observed when fraction of drug permeated was correlated with the fraction of drug absorbed at the same time point. Gamma scintigraphy imaging on rabbit following transdermal patch application was performed to ascertain the localization of drugs in rabbit brain.

Design, characterization, and evaluation of intranasal delivery of ropinirole-loaded mucoadhesive nanoparticles for brain targeting

Context: Parkinson disease (PD) is a common, progressive neurodegenerative disorder, characterized by marked depletion of striatal dopamine and degeneration of dopaminergic neurons in the substantia nigra.Objective: The purpose of the present study was to investigate the possibility of targeting an anti-Parkinson’s drug ropinirole (RH) to the brain using polymeric nanoparticles.Materials and methods: Ropinirole hydrochloride (RH)-loaded chitosan nanoparticles (CSNPs) were prepared by an ionic gelation method. The RH-CSNPs were characterized for particle size, polydispersity index (PDI), zeta potential, loading capacity, entrapment efficiency in vitro release study, and in vivo distribution after intranasal administration.Results and discussion: The RH-CSNPs showed sustained release profiles for up to 18 h. The RH concentrations (% Radioactivity/g) in the brain following intranasal administration (i.n.) of RH-CSNPs were found to be significantly higher at all the time points compared with RH solution. The concentration of RH was highest in the liver (7.210 ± 0.52), followed by kidneys (6.862 ± 0.62), intestine (4.862 ± 0.45), and lungs (4.640 ± 0.92) in rats following i.n. administration of RH-CSNPs. Gamma scintigraphy imaging in rats was performed to ascertain the localization of drug in the brain following intranasal administration of formulations. The brain/blood ratios obtained (0.251 ± 0.09 and 0.386 ± 0.57 of RH (i.n.) and RH-CSNPs (i.n.), respectively) at 0.5 h are indicative of direct nose to brain transport, bypassing the blood–brain barrier (BBB).Conclusion: The novel formulation showed the superiority of nose to brain delivery of RH using mucoadhesive nanoparticles compared with other delivery routes reported earlier.

Establishment of a trimodality analytical platform for tracing, imaging and quantification of gold nanoparticles in animals by radiotracer techniques.

This study aims to establish a (198)Au-radiotracer technique for in vivo tracing, rapid quantification, and ex vivo visualization of PEGylated gold nanoparticles (GNPs) in animals, organs and tissue dissections. The advantages of GNPs lie in its superior optical property, biocompatibility and versatile conjugation chemistry, which are promising to develop diagnostic probes and drug delivery systems. (198)Au is used as a radiotracer because it simultaneously emits beta and gamma radiations with proper energy and half-life; therefore, (198)Au can be used for bioanalytical purposes. The (198)Au-tagged radioactive gold nanoparticles ((198)Au-GNPs) were prepared simply by irradiating the GNPs in a nuclear reactor through the (197)Au(n,γ)(198)Au reaction and subsequently the (198)Au-GNPs were subjected to surface modification with polyethylene glycol to form PEGylated (198)Au-GNPs. The (198)Au-GNPs retained physicochemical properties that were the same as those of GNP before neutron irradiation. Pharmacokinetic and biodisposition studies were performed by intravenously injecting three types of (198)Au-GNPs with or without PEGylation into mice; the γ radiation in blood specimens and dissected organs was then measured. The (198)Au-radiotracer technique enables rapid quantification freed from tedious sample preparation and shows more than 95% recovery of injected GNPs. Clinical gamma scintigraphy was proved feasible to explore spatial- and temporal-resolved biodisposition of (198)Au-GNPs in living animals. Moreover, autoradiography, which recorded beta particles from (198)Au, enabled visualizing the heterogeneous biodisposition of (198)Au-GNPs in different microenvironments and tissues. In this study, the (198)Au-radiotracer technique facilitated creating a trimodality analytical platform for tracing, quantifying and imaging GNPs in animals.

Regional deposition of mometasone furoate nasal spray suspension in humans.

Nasal deposition studies can demonstrate whether nasal sprays treating allergic rhinitis and polyposis reach the ciliated posterior nasal cavity, where turbinate inflammation and other pathology occurs. However, quantifying nasal deposition is challenging, because in vitro tests do not correlate to human nasal deposition; gamma scintigraphy studies are thus used. For valid data, the radiolabel must distribute, as the drug, into different-sized droplets, remain associated with the drug in the formulation after administration, and not alter its deposition. Some nasal deposition studies have demonstrated this using homogenous solutions. However, most commercial nasal sprays are heterogeneous suspensions. Using mometasone furoate nasal suspension (MFS), we developed a technique to validate radiolabel deposition as a surrogate for nasal cavity drug deposition and characterized regional deposition and nasal clearance in humans. Mometasone furoate (MF) formulation was spiked with diethylene triamine pentacaetic acid. Both unlabeled and radiolabeled formulations (n = 3) were sprayed into a regionally divided nasal cast. Drug deposition was quantified by high pressure liquid chromatography within each region; radiolabel deposition was determined by gamma camera. Healthy subjects (n = 12) were dosed and imaged for six hours. Scintigraphic images were coregistered with magnetic resonance imaging scans to quantify anterior and posterior nasal cavity deposition and mucociliary clearance. The ratio of radiolabel to unlabeled drug was 1.05 in the nasal cast and regionally appeared to match, indicating that in vivo radiolabel deposition could represent drug deposition. In humans, MFS delivered 86% (9.2) of metered dose to the nasal cavity, approximately 60% (9.1) of metered dose to the posterior nasal cavity. After 15 minutes, mucociliary clearance removed 59% of the initial radiolabel in the nasal cavity, consistent with clearance rates from the ciliated posterior surface. MFS deposited significant drug into the posterior nasal cavity. Both nasal cast validation and mucociliary clearance confirm the radiolabel deposition distribution method accurately represented corticosteroid nasal deposition.

Development and clinical study of submicronic-atropine sulphate respiratory fluid as a novel organophosphorous poisoning antidote

Context: Increased use of organophosphate insecticides (OPI) and possibility of terror groups using stocks of nerve agents underscore the need to develop effective and safe antidotes. While intramuscular administration of antidotes like atropine sulphate (AS) has certain lacunae, intravenous route may not be always feasible in emergency field conditions.Objective: Objective was (a) to develop a novel inhalable submicronic-AS respiratory fluid as potential antidote for OPI poisoning, (b) in-vitro and in-vivo evaluation in terms of respiratory fraction, and (c) clinical study to assess drug bioavailability in blood and atropinization pattern post-inhalation.Methods: Formulation was optimized on the basis of particle size of aerosolized droplets and in-vitro nebulization rate. Anderson cascade impaction (ACI) studies were carried out to validate the advantage of test formulation in terms of respirable fraction. Six healthy volunteers were inhaled the test formulation and blood bioavailability and atropinization were noted serially. Gamma scintigraphy was used to quantify total and regional lung deposition of nebulized AS in-vivo.Results: The formulation was optimized using 30% ethanol–saline with particle size in the range of 350–500 nm. In-vitro ACI data showed high respirable fraction (82.6 ± 3.1%) for the test formulation. In-vivo scintigraphy suggested whole lung deposition of 80.2 ± 6.8% of the total inhaled dose. Early blood bioavailability and atropinization pattern confirmed that therapeutic concentration of the drug in blood was reached within 5 min.Conclusions: 3% submicronic-AS respiratory fluid might be used as potential prophylactic/therapeutic option against OPI poisoning with several advantages over intramuscular injection, including early blood bioavailability and atropinization.

Surgical treatment of persistent tertiary hyperparathyroidism induced by parathyroid adenomas in the aortopulmonary window

Background. Aortopulmonary window is a rare localization of ectopic parathyroid glands. This localization is the difficulty in diagnosis and surgical treatment, especially in conditions of the heavy somatic pathology that develops with prolonged of kidney replacement therapy. Persistence of tertiary hyperparathyroidism after cervical revision does not give in medical treatment, accompanied by the progression of bone and systemic symptoms of the disease, including death.Materials and Methods. Illustrates a case successful diagnosis and surgical treatment this rare disease. We discuss the treatment and diagnostic tactics. Female patient (age 66) had the experience of peritoneal dialysis for 6 years. She underwent cervical parathyroidectomy. Ectopic mediastinal paratiroma detected by gamma scintigraphy (from 99mTc-MIBI). Determination of the exact tumor location proved to be impossible before the surgery due to bad mental condition of the patient. Localization of adenomas was defined on the surgery after a sternotomy. Results. Operation efficiency proved decrease parathyroid hormone from 2095 pg / ml (before operation) to 10 pg / ml (1.5 months after surgery). After surgery, there was a mediastinal hematoma. The patient was discharged 21 days after surgery healed by.Conclusions. The use a sternotomy leads to the removal of the tumor. This access may be used when an unknown location. This access is a forced for tertiary hyperparathyroidism.

Brain targeting by intranasal drug delivery (INDD): a combined effect of trans-neural and para-neuronal pathway

The effectiveness of intranasal drug delivery for brain targeting has emerged as a hope of remedy for various CNS disorders. The nose to brain absorption of therapeutic molecules claims two effective pathways, which include trans-neuronal for immediate action and para-neuronal for delayed action. To evaluate the contribution of both the pathways in absorption of therapeutic molecules and nanocarriers, lidocaine, a nerve-blocking agent, was used to impair the action potential of olfactory nerve. An anti-Parkinson drug ropinirole was covalently complexes with 99mTc in presence of SnCl2 using in-house developed reduction technology. The radiolabeled formulations were administered intranasally in lidocaine challenged rabbit and rat. The qualitative and quantitative outcomes of neural and non-neural pathways were estimated using gamma scintigraphy and UHPLC-MS/MS, respectively. The results showed a significant (p ≤ 0.005) increase in radioactivity counts and drug concentration in the brain of rabbit and rat compared to the animal groups challenged with lidocaine. This concludes the significant contribution (p ≤ 0.005) of trans-neuronal and para-neuronal pathway in nose to brain drug delivery. Therefore, results proved that it is an art of a formulator scientist to make the drug carriers to exploit the choice of absorption pathway for their instant and extent of action.

Oral sustained-release suspension based on a novel taste-masked and mucoadhesive carrier–ion-exchange fiber

The purpose of this study was to evaluate the feasibility of ion-exchange fiber ZB-1 as a novel carrier in oral taste-masked mucoadhesive sustained-release suspensions. Propranolol (PPN) hydrochloride was selected as a model drug with good water solubility, short half life and bitter taste. The PPN-fiber complexes (PF) were prepared by a batch process and coated with Eudragit® RS100. Gamma scintigraphy was performed on fasted volunteers revealed about 30% ZB-1 and more than 50% coated ZB-1 were still remaining in the stomach at 6h. In vitro results showed the releases of PF and coated PPN-fiber complexes (C-PF) were sustained. The release, drug content and particle size of C-PF were influenced by coat to core ratio, concentration of coating material and rotation rate. The suspension was stable after standing for 30 days in 0.5% Carbopol® with no release rate and taste changed. The administration of C-PF suspension to rats resulted a significant different (P<0.05) improvement of the plasma drug level and prolongation of the release. However, because of the burst effect, the Cmax values of PF suspension didn't differ from drug solution (P>0.05). Furthermore, a linear relationship between in vitro dissolution and in vivo absorption was observed.

Aerosol deposition in the human lung in reduced gravity.

The deposition of aerosol in the human lung occurs mainly through a combination of inertial impaction, gravitational sedimentation, and diffusion. For 0.5- to 5-μm-diameter particles and resting breathing conditions, the primary mechanism of deposition in the intrathoracic airways is sedimentation, and therefore the fate of these particles is markedly affected by gravity. Studies of aerosol deposition in altered gravity have mostly been performed in humans during parabolic flights in both microgravity (μG) and hypergravity (~1.6G), where both total deposition during continuous aerosol mouth breathing and regional deposition using aerosol bolus inhalations were performed with 0.5- to 3-μm particles. Although total deposition increased with increasing gravity level, only peripheral deposition as measured by aerosol bolus inhalations was strongly dependent on gravity, with central deposition (lung depth<200 mL) being similar between gravity levels. More recently, the spatial distribution of coarse particles (mass median aerodynamic diameter≈5 μm) deposited in the human lung was assessed using planar gamma scintigraphy. The absence of gravity caused a smaller portion of 5-μm particles to deposit in the lung periphery than in the central region, where deposition occurred mainly in the airways. Indeed, 5-μm-diameter particles deposit either by inertial impaction, a mechanism most efficient in the large and medium-sized airways, or by gravitational sedimentation, which is most efficient in the distal lung. On the contrary, for fine particles (~1 μm), both aerosol bolus inhalations and studies in small animals suggest that particles deposit more peripherally in μG than in 1G, beyond the reach of the mucociliary clearance system.

Topical delivery of fluorescence (6-Cf) labeled and radiolabeled (99m-Tc) cisplatin and imiquimod by a dual drug delivery system.

The present investigation deals with the development of topical (top.) formulation for co-delivery of cisplatin and imiquimod to enhance the antitumor efficacy of the drug for skin-cited malignancies even in immune compromised patient. Cisplatin (CDDP) and imiquimod-loaded protransfersome gel (CDDP-Imi-Pts gel) formulation was characterized for entrapment efficiency, pH, and viscosity. Further, fluorescence-labeled (6-carboxyfluorescin) and radiolabeled ((99m) technetium) drug-loaded formulations were compared with respect to biodistribution and pharmacokinetic studies. Gamma scintigraphy of mice following radiolabeled formulation administrations was performed to accomplish the localization of drugs in various organs. The percentage entrapment efficiency of cisplatin and imiquimod in the protransfersome gel formulations were found to be 36.22 ± 6.41 and 63.11 ± 3.73. The skin/blood localization ratio of 1.096, 120.13, 0.174, and 349.88 was found for intraperitoneal radiolabeled drug solution ((99m-)Tc-CDDP-Imi-Sol), top. radiolabeled drug-loaded protransfersome gel formulation ((99m-)Tc-CDDP-Imi-Pts gel), intraperitoneal 6-carboxyfluorescin labeled drug solution (6-Cf-CDDP-Imi-Sol), top. 6-carboxyfluorescin labeled drug-loaded protransfersome gel formulation (6-Cf-CDDP-Imi-Pts gel), respectively after 0.5h of administration. CDDP-Imi-Pts gel has a potential for site specific delivery and reduces the systemic toxicity of anti cancer drugs. These findings suggest that the cisplatin-imiquimod co-delivery offers an attractive, novel approach for treatment of skin-cited malignancies.

Preparing, characterizing, and evaluating chitosan/fucoidan nanoparticles as oral delivery carriers

In designing an effective oral delivery system, the harshness of the gastrointestinal tract is a key limitation. Therefore, developing a pH-responsive carrier is crucial. We designed a chitosan/fucoidan nanoparticle (CS/F NP) and evaluated its potential as an oral delivery carrier. The results indicate that the CS/F NPs were successfully prepared based on their electrostatic interactions. They were approximately 380 nm, revealing significant pH-sensitive properties as the weight ratio of CS to F was 1:1. The isoelectric point of the CS/F NPs was 5.7. Using gamma scintigraphy, the 99m Tc-methylene diphosphonate encapsulated CS/F NPs were quite stable at pH 2.5 and decomposed at pH 7.4. For long-term storage, trehalose (20 %, w/v) is a suitable cryoprotectant. The outcome of the transepithelial electric resistance (TEER) of the Caco-2 monolayer shows that CS/F NPs effectively enhanced the opening of the cell tight junction. Briefly, the CS/F NPs developed are promising carriers for an oral delivery system.

IN VIVO EVALUATION OF MUCOADHESIVE PROPERTIES OF NANOLIPOSOMAL FORMULATIONS UPON COATING WITH TRIMETHYLCHITOSAN POLYMER

Objective(s): Drug delivery via mucosal routes has been confirmed to be effective in inducing strong immune responses. Liposomes could enhance immune responses and mucoadhesive potentials, make them useful mucosal drug delivery systems. Coating of liposomes by mucoadhesive polymers succeeded in enhancing immune responses. Our studies aim at preparation and characterization of trimethylchitosan-coated nanoliposomes for nasal delivery of a model antigen, tetanus toxoid (TT). Materials and Methods: Anionic liposomes were prepared by dehydration-rehydration method with an average size of 100 nm and were coated with 0.01% (w/v) solution of trimethyulchitosan (TMC) with 50±10% of quaternization. Surface properties and zeta potential were evaluated by DLS. Antigen stability and integrity were studied by SDS-PAGE electrophoresis. Nasal clearance rate and mucoadhesive properties of liposomes were studied by gamma scintigraphy method using 99m Tc-labelled liposomes. Results: The zeta potential of non-coated and TMC-coated liposomes was -40 and +38.8, respectively. Encapsulation rate of tetanus toxoid was 77 ± 5.5%. SDS-PAGE revealed that the antigens remained intact during formulation procedure. Gamma scintigraphy confirmed that both types of liposomes could remain in nasal cavity up to ten folds over the normal residence time for conventional nasal formulations. Conclusion: TMC-coated nanoliposomes have several positive potentials including good mucoadhesive properties, preserved integrity of loaded antigen and presence of TMC as a mucoadhesive polymer with innate immunoadjuvant potential which make them suitable for efficient adjuvant/delivery system.

Preparation and evaluation of three mucoadhesive dosage forms using 99mTc–Ofloxacin

Preparation of three mucoadhesive formulations was optimized and pharmaceutically evaluated. Ofloxacin was radiolabeled with 99mTc and radiolabeled complex was characterized by HPLC. 99mTc–Ofloxacin was added as a tracer to the formulations namely Oflox C934, Oflox C940 and Oflox HPMC and the formulations were fed orally to rats. Imaging studies were carried out to assess the prolonged gastric retention of the formulations. 99mTc–Ofloxacin served as a good tracer for studying the pharmacokinetics of three controlled release mucoadhesive dosage forms by gamma scintigraphy studies.

A novel gastroretentive porous microparticle for anti-Helicobacter pylori therapy: Preparation, in vitro and in vivo evaluation

Gastroretentive drug delivery system is a promising option for the treatment of Helicobacter pylori infection, which can prolong gastric residence time and supply high drug concentration in the stomach. In the present study, a low density system of metronidazole-loaded porous Eudragit® RS microparticle with high drug loading capacity (>25%) was fabricated via electrospray method. The porous structure and size distribution of microparticles were affected by polymer concentration and flow rate of solution. FTIR and XRD analyses indicated that drug has been entrapped into the porous microparticles. In addition, sustained release profiles and slight cytotoxicity in vitro were detected. Gamma scintigraphy study in vivo demonstrated that ¹³¹I-labeled microparticles retained in stomach for over 8h, and about 65.50% radioactive counts were finally detected in the region of interest. The biodistribution study confirmed that hotspot of radioactivity was remaining in the stomach. Furthermore, metronidazole-loaded porous microparticles can eradicate H. pylori completely with lower dose and administration frequency of antibiotic compared with pure drug, which were also more helpful for the healing of mucosal damages. These results suggest that prepared porous microparticle has the potential to provide better treatment for H. pylori infection.

Evaluation Bone Uptake of Alendronate Sodium Via Vaginal Route by Gamma Scintigraphy, Vaginal Uptake of Alendronate Sodium

Alendronate sodium (ALD) is a second generation amino bisphosphonate that use for treatment of bone diseases. Since ALD is poorly absorbed from the gastrointestinal tract and its absorption is markedly reduced by food, the aim of this study is to evaluate the bone uptake of ALD through vaginal route. To evaluate the bone uptake of ALD by gamma scintigraphy, ALD was radiolabeled with Technetium-99 m ( 99m Tc). Vaginal supposi-tories and injectable solution of 99m Tc-ALD was prepared and gamma scintigraphy studies were performed with intravaginally and intravenously 99m Tc-ALD applied rabbits. The results were revealed that ALD was successfully labeled with 99m Tc. After intravaginal and intravenous application, 99m Tc-ALD showed a high uptake in bone. Despite accumulation times and uptake ratios showed differences between administration routes, our preliminary observations suggest that the intravaginal route appears to be a viable alternative for ALD application and should be evaluated in future clinical studies.

Mathematical modeling of individual gastric emptying of pellets in the fed state

In the present work mathematical modeling of individual gastric emptying (GE) profiles of pellets in the fed state was performed. Twenty two profiles from healthy subjects obtained by gamma scintigraphy were collected by literature search. A variety of shapes were found: linear, exponential, as a series of small boluses, two phase as fast GE followed by slow GE and the opposite, and curves containing one or more intervals with no GE. The Elashoff, Siegel, and double Weibull models were fitted to each of the individual GE profiles. Additionally, the values of parameters reflecting the time when GE of pellets started were calculated on the basis of the models and were compared to the experimentally determined values. The double Weibull model was proven to be the most capable of fitting various GE patterns and could be thus implemented in biorelevant dissolution testing and in prediction of in vivo dissolution profiles.