Stability of Compounded Topical Nifedipine in Cream, Gel, and Ointment Bases.

The objective of this study was to investigate the stability of compounded nifedipine cream in gel and ointment formulations dispensed in white plastic and glass amber jars. Extemporaneously compounded nifedipine cream (Glaxal Base), gel (K-Y Jelly), and ointment (Aquaphor) in white plastic and glass amber jars were stored at 4°C, 23°C, and 40°C. We determined potency on days 0, 7, 14, 30, 60, and 90, and subsequently assigned beyond-use-dates based on United States Pharmacopeia recommendations, organoleptic properties, and pH changes. Nifedipine potency in cream and ointment stored in white plastic jars was within ±10% of initial for 90 days (excluding day 14 for cream). In glass amber jars, potency was outside the acceptable range by day 14 at 23°C but within range for 90 days at 4°C (excluding day 30). Nifedipine potency was maintained for 90 days in both jars at 23°C and 4°C (excluding day 30) and in white plastic jars at 40°C, but 60 days stored in glass amber jars. The pH of formulations was stable with changes of less than 1-unit pH. At 40°C, a significant decrease in apparent viscosity of cream was evident on day 90. There was a decrease in apparent viscosity and phase separation of the ointment at 40°C and an increase in apparent viscosity (difficult to mix) at 4°C on day 14 onwards. Significant organoleptic changes were observed by day 7 at 40°C (decrease in apparent viscosity and abnormal odor by day 90), day 30 at 4°C (thicker consistency), and day 90 at 23°C (abnormal odor). Storage in white plastic jars at 23°C is recommended for compounded topical nifedipine cream and ointment (for 90 days), and for gel (60 days).

Hemodynamic Assessment and In vivo Catabolism of Adenosine 5'-triphosphate in Doxorubicin or Isoproterenol-induced Cardiovascular Toxicity.

OBJECTIVE: Previous studies have shown that catabolism of adenosine 5'-triphosphate (ATP) in systemic blood is a potential surrogate biomarker for cardiovascular toxicity. We compared the acute toxicity of high doses of doxorubicin (DOX) and isoproterenol (ISO) on hemodynamics and ATP catabolism in the systemic circulation. METHODS: sprague Dawley (SD) rats (n = 8 - 11) were each given either a single dose of 30 mg/kg ISO, or a twice-daily dose of 10 mg/kg of DOX or 4 doses of normal saline (control) by subcutaneous injection. Blood samples were collected up to 6 hours for measuring concentrations of ATP and its catabolites. Hemodynamics was recorded continuously. The difference was considered significant at p < 0.05 (ANOVA). RESULTS: Mortality was 1/8, 5/11, and 0/11 for the DOX, ISO, and control groups, respectively. Systolic blood pressure was significantly lower in the DOX and ISO treated rats than in control measured at the last recorded time (76 ± 9 for DOX vs. 42 ± 8 for ISO vs. 103 ± 5 mmHg for control, p < 0.05 for all). Blood pressure fell gradually after the final injection for both DOX and control groups, but abruptly after ISO, followed by a rebound and then gradual decline till the end of the experiment. Heart rate was significantly higher after ISO, but there were no differences between the DOX and control rats (p > 0.05). RBC concentrations of ADP and AMP, and plasma concentrations of adenosine and uric acid were significantly higher in the ISO group. In contrast, hypoxanthine concentrations were significantly higher in the DOX treated group (p < 0.05). CONCLUSION: Acute cardiovascular toxicity induced by DOX and ISO may be measured by changes in hemodynamics and breakdown of ATP and adenosine in the systemic circulation, albeit a notable qualitative and quantitative difference was observed.

Stability of Compounded Diltiazem Hydrochloride in Cream, Ointment, and Gel Formulations for Topical Use.

Interest in the topical use of compounded diltiazem has increased. Published information on the stability of such products is scarce. The objective of this study was to investigate the stability of diltiazem hydrochloride compounded in cream (Glaxal Base), ointment (white petrolatum), and hydroxyethyl cellulose-based gel over 90 days at room (23°C), refrigerator (4°C), and elevated (40°C) temperatures, stored in white plastic and glass amber containers. Organoleptic properties, pH changes, and United States Pharmacopeia recommendations were used for assigning beyond-use-dates. The results showed that the currently recommended United States Pharmacopeia beyond-use date of 30 days is acceptable for diltiazem (2%) in Glaxal Base at 4°C and 23°C in either white plastic or glass amber jars. The cream, however, is not recommended for use if exposed to elevated temperatures (40°C) in white plastic jars but may be used within 7 days if stored in glass amber jars. A beyond-use date of 90 days for diltiazem (2%) hydroxyethyl cellulose-based gel, when maintained at 4°C or 23°C, in either white plastic or glass amber jars, is recommended. Gels exposed to elevated temperatures (40°C) should be used within14 and 30 days in glass amber and white plastic jars, respectively. Lastly, a BUD of 90 days for diltiazem (2%) ointment (white petrolatum) at 23°C stored in either jar type is acceptable. Ointment formulations exposed to elevated temperatures (40°C) may be used within 7 days in white plastic jars. Diltiazem (2%) in white petrolatum should not be stored at 4°C.

Drug-release Assessment of Compounded Topical Nifedipine and Diltiazem in Commonly Used Bases for Wound Healing.

The objective of this study was to determine release profiles of extemporaneously compounded nifedipine and diltiazem in commonly used bases in pharmacy practice. Release of nifedipine 0.2%, 2%, and 10% (w/w) from Glaxal Base, K-Y Jelly, and Aquaphor Healing Ointment, and of diltiazem 2% (w/w) from GlaxalBase, hydroxyethyl cellulose-based gel, and white petrolatum was quantified using the Franz-cell diffusion system. The cumulative release was determined at 0.5 hour, 1 hour, 1.5 hours, 2 hours, 3 hours, 4 hours, and 6 hours. Two-way ANOVA with Tukey's posthoc test was used for statistical analyses, with a P-value of <0.05 considered significant. At a 0.2% concentration, cumulative nifedipine release was highest from Glaxal Base. At 2% and 10% concentrations, nifedipine release was highest from K-Y Jelly, although this was only significantly different from Glaxal Base at 6 hours and 1.5 hours, 4 hours, 6 hours (P<0.05), respectively. Diltiazem release from Glaxal Base and white petrolatum was significantly lower than the gel (P<0.05). No significant difference in diltiazem release from Glaxal Base at 0.5 hour was observed versus white petrolatum (P>0.05). Nifedipine and diltiazem release both followed Higuchi's mathematical model with the highest coefficient of determination (R2) for all formulations. Of the bases studies, Glaxal Base is the recommended base for compounding topical nifedipine (0.2%). For higher concentrations of nifedipine (2% and10%), both Glaxal Base and K-Y Jelly are suitable options for base selection. A hydroxyethylcellulose-based gel is recommended for topical diltiazem (2%).

Compounded Topical Amitriptyline for Neuropathic Pain: In Vitro Release from Compounding Bases and Potential Correlation with Clinical Efficacy.

BACKGROUND: Topical amitriptyline has been described as having mixed clinical efficacy for neuropathic pain. A few case reports using higher concentrations of this compound found clinical benefit, but many of these studies did not describe the components used in formulating the amitriptyline preparations. OBJECTIVE: To generate reproducible clinical measures of the characteristics of amitriptyline diffusion from selected compounding bases, to support a scientific approach to base selection when compounding this drug for neuropathic pain. METHODS: Amitriptyline hydrochloride (1%, 5%, and 10%) was compounded with 3 proprietary compounding bases: Lipoderm base, Emollient Cream, and Mediflo 30 pluronic lecithin organogel (PLO) gel. In vitro release of the drug from each base and subsequent permeation across artificial human skin were investigated with the Franz diffusion system. Amitriptyline release mechanisms were determined with kinetic models. How quickly and to what extent the drug leaves each base to diffuse through the skin were characterized by determining steady-state flux, cumulative permeation, and lag times. RESULTS: Release of amitriptyline was significantly higher from the Mediflo PLO gel than from the Lipoderm base or Emollient Cream (p < 0.05). Mean cumulative drug release after 24 h, from the 10% formulation, was 23.9% (standard deviation [SD] 4.1%) for Lipoderm base, 41.8% (SD 3.1%) for Emollient Cream, and 53.2% (SD 7.7%) for Mediflo PLO gel. A high percentage of amitriptyline was retained in all 3 bases. Although amitriptyline release was highest with Mediflo PLO gel, this base resulted in significantly lower cumulative permeation relative to Lipoderm base and Emollient Cream (p < 0.05). There was a strong overall correlation between amitriptyline concentration, lag time, and flux. Higher concentrations were associated with significantly lower lag times and increased flux. The highest lag time and flux were observed for Mediflo PLO gel. CONCLUSION: These data indicate that the therapeutic effectiveness of compounded amitriptyline for neuropathic pain depends on its diffusion out of the compounding bases and penetration through the skin.

CONTEXTE: L'efficacité clinique de l'amitriptyline topique contre les douleurs neuropathiques a été décrite comme étant variable. Quelques rapports utilisant des concentrations plus élevées de cette base indiquent des avantages cliniques, mais bon nombre d'entre eux ne décrivent pas les composants des préparations d'amitriptyline. OBJECTIF: Établir des mesures cliniques reproductibles des caractéristiques de la diffusion de l'amitriptyline selon une approche scientifique de la sélection des bases pour la préparation de ce médicament contre les douleurs neuropathiques. MÉTHODES: Le chlorohydrate d'amitriptyline (1 %, 5 % et 10 %) a été mélangé à trois bases de préparations magistrales brevetées : la base Lipoderm, la crème émolliente et le gel Mediflo PLO 30. La libération in vitro du médicament de chaque base et la perméation qui s'en est suivie dans la peau humaine artificielle ont été étudiées à l'aide du système de diffusion Franz. La définition des mécanismes de libération de l'amitriptyline repose sur des modèles cinétiques. La rapidité et la durée de libération du médicament de chaque base pour se diffuser dans la peau ont été caractérisées par la détermination du flux constant, de la perméation cumulée et des temps de latence. RÉSULTATS: La libération de l'amitriptyline était sensiblement plus élevée quand le produit était mélangé au gel Mediflo PLO plutôt qu'à la base Lipoderm ou à la crème émolliente (p < 0,05). La libération cumulée du médicament, formule 10 %, après 24 h était de 23,9 % (écart type [É.T.] ± 4,1 %) avec la base Lipoderm; 41,8 % (É.T. ± 3,1 %) avec la crème émolliente et 53,2 % (É.T. ± 7,7 %) avec le gel Mediflo PLO. Les trois bases retenaient un pourcentage élevé d'amitriptyline. Bien que la libération d'amitriptyline était plus élevée en présence du gel Mediflo PLO, la perméation cumulée de cette base par rapport à celle de la base Lipoderm et de la crème émolliente était sensiblement moins élevée (p < 0,05). L'observation a révélé une forte corrélation générale entre la concentration d'amitriptyline, le temps de latence et le flux. Les concentrations plus élevées étaient associées à des temps de latence sensiblement moins élevés. C'est le gel Mediflo PLO qui a démontré une supériorité du temps de latence et du flux. CONCLUSION: Ces données indiquent que l'efficacité thérapeutique de la préparation d'amitriptyline contre les douleurs neuropathiques dépend de sa diffusion hors des bases dans les préparations magistrales et de sa pénétration dans la peau.

Compounded Topical Gabapentin for Neuropathic Pain: Does Choice of Base Affect Efficacy?

The objective of this study was to investigate the effect of Lipoderm Cream, VersaBase Gel, and Emollient Cream on the release and permeation of gabapentin formulated for neuropathic pain. Gabapentin of different strengths (1%, 5%, and 10%) was compounded with the bases, diffusion of the drug from thebases, and permeation through artificial skin model studied with Franz diffusionsystem. Steady-state flux, cumulative permeation, and lag times were calculated,and release mechanisms modelled with first order, second-order, Higuchi, Korsmeyer-Peppas, and Hixon-Crowell kinetic models. Gabapentin recovery from VersaBase Gel, Lipoderm Cream, and Emollient Cream was 100.8 ± 2.7%, 101.3 ± 1.2%, and 104.9 ± 3.3%, respectively. Gabapentin completely diffused out of the three bases within 6 hours of application according to the Higuchi model. Flux of the drug appeared to be concentration-dependent with no permeation occurring at 1% strength. Whereas, 5% and 10% strengths in Lipoderm Cream permeated the skin rapidly, the same concentrations in Emollient Cream and VersaBase Gel required 60-minutes and 120-minutes lag times, respectively. For the three bases, a strong correlation was observed between lag times and flux. The overall permeation in VersaBase Gel and Lipoderm Base was not significantly different (P>0.05). However, Emollient Cream resulted in a significantly lower total permeation compared to other bases (P<0.05). As the formulations are for pain management, products with no lag times and higher flux are preferable. Although VersaBase Gel and Emollient Cream displayed some gabapentin permeability, it is important to consider gabapentin stability in these bases prior to use.

Compounded gabapentin for neuropathic pain: Stability and beyond-use date (BUD) in some commonly used bases.

OBJECTIVES: To investigate the stability and beyond-use date (BUD) of topical gabapentin in 3 commonly used bases. METHODS: Lipoderm cream, Versabase gel, and Emollient cream were used to compound gabapentin (10%). The products were stored in Ecolojars, kept at 25°C, 4°C, and 40°C, and samples were collected on different days (days 0, 14, 28, and 90). Potency, stability, and organoleptic changes were monitored. RESULTS: At 25°C and 40°C, the potency of gabapentin in Lipoderm cream significantly increased (P < 0.05) after 28 and 90 days, respectively. In contrast, gabapentin degraded in Emollient cream (P < 0.05). At 25°C, the organoleptic properties of the drug compounded with Lipoderm cream (25°C) remained consistent for up to 28 days but showed signs of physical changes in other bases. Gabapentin recrystallized from Versabase gel and Emollient cream within 14 days. CONCLUSION: Gabapentin compounded with Lipoderm cream for topical use was stable in Ecolojars for 28 days at 25°C. Under the same conditions, the drug was not stable in Versabase gel and Emollient cream. Based on our stability and potency data, the beyond-use date of currently dispensed gabapentin (10%) formulations with Lipoderm cream should not be extended beyond the currently assigned 30-day mark, even when refrigerated. It is unclear whether the stability of these formulations is improved if stored in air-tight containers.

Stability Assessment of Topical Amitriptyline Extemporaneously Compounded with Lipoderm Base, PLO Gel Mediflo 30, and Emollient Cream.

Extemporaneous topical compounds for neuropathic pain offers an alternative or adjunct approach to existing therapies for patients. Assigning evidence-based beyond-use dating prior to dispensing topical medications is a legal requirement by pharmacy governing bodies. The purpose of this study was to utilize a validated stability-indicating high-performance liquid chromatography assay to determine beyond-use dating of topical amitriptyline in three different bases (Lipoderm Base, PLO Gel Mediflo 30, Emollient Cream) at three different temperatures [room temperature (25°C), refrigeration (4°C), and high temperature (40°C)]. Amitriptyline was stable after 90 days at room temperature in both Lipoderm Base and PLO Gel Mediflo 30. However, it was not stable at 40°C in Emollient Cream, irrespective of storage conditions.

Adenosine and Adenosine 5'-triphosphate Catabolism in Systemic Blood as a Potential Biomarker for Doxorubicin Cardiotoxicity in an Experimental Rat Model in vivo.

BACKGROUND: Previous studies have shown that metabolism of adenosine 5'-triphosphate (ATP) in systemic blood is a potential surrogate biomarker for cardiovascular toxicity. OBJECTIVE: To investigate the acute effect of high dose of doxorubicin (DOX) on adenosine and ATP catabolism in systemic blood in vivo. METHOD: Sprague Dawley (SD) rats were each given either 10 mg/kg of DOX (n = 8) or normal saline (1 mL/kg, n = 11) twice daily for 4 doses by subcutaneous (sc) injection. Blood samples were collected sequentially for up to 6 hours for measuring circulating concentrations of ATP, adenosine and their metabolites. Hemodynmic recording was obtained continuously after the last injection. The difference in response between groups was considered significant at p < 0.05 (t-test). RESULTS: Diastolic blood pressure (DBP) was significantly lower in the DOX treated rats than in the control before the final injection (87 ± 12 vs. 104 ± 11 mmHg, p < 0.05). Blood pressure fell gradually after the last injection and the decrease was significantly greater in the DOX treated group (p < 0.05). Plasma concentration of adenosine was significantly lower in the DOX treated group. In contrast, plasma concentrations of uric acid and hypoxanthine, as well as Red Blood Cell (RBC) concentrations of AMP, were significantly higher (p < 0.05). CONCLUSION: Acute cardiotoxicity induced by DOX may be measured by the increased breakdown of ATP to AMP in the RBC and also breakdown of adenosine to hypoxanthine and uric acid in plasma.

Models for the study of nasal and sinus physiology in health and disease: A review of the literature.

Objective: Chronic sinusitis is a very common yet poorly understood medical condition with significant morbidity. Hence, it remains an entity that is difficult to treat with unsatisfactory outcomes of current management options. This necessitates research into the etiology and pathophysiology of the condition to enhance our knowledge and the therapeutic options. Unfortunately, this kind of research is not always feasible on human subjects due to practical and ethical limitations. Therefore, an alternative model that simulates the disease had to be found in order to overcome these limitations. These models could either be in vivo or in vitro. The aim of our review is to summarize the research findings and key discoveries of both in vivo and in vitro models of chronic sinusitis that have enhanced our understanding of the condition today and have paved the way for the future research of tomorrow. Data Sources: PubMed literature review. Methods: A review of the literature was conducted to identify the main successful in vivo and in vitro models for chronic sinusitis. Results: Creating a successful model for chronic sinusitis is no easy task. Over the years, both in vivo animal models and in vitro tissue culture models were proposed, with each model having its accolades and pitfalls, with the ideal model remaining elusive to this day. However, advancing three-dimensional cell culturing techniques seems to be a promising new way to find a more accurate model. Conclusion: None of the current models is perfect for a thorough study of chronic sinusitis. However, three-dimensional cell cultures have the potential to bridge the gap between in vivo and in vitro studies. Level of Evidence: NA.

Improving the Efficiency of Respiratory Drug Delivery: A Review of Current Treatment Trends and Future Strategies for Asthma and Chronic Obstructive Pulmonary Disease.

Asthma and chronic obstructive pulmonary disease (COPD) are heterogeneous airway diseases associated with significant morbidity and mortality. Pharmacological treatment is delivered primarily through the inhalation route using various devices. Optimal disease control is highly dependent upon patient adherence. Both patients with asthma and COPD are prone to exacerbations leading to hospitalization, which can significantly impact quality of life. Poor adherence is a complex and multifactorial problem that does not have one simple solution. However, it is the biggest risk factor for exacerbations and consequently high healthcare utilization. This review discusses the complex and multifactorial obstacles that impact patient adherence as well as the effect on overall treatment outcomes and healthcare utilization. We also critically examined and compared relatively recent improvements in breath-activated pressurized metered dose inhalers, dry powder inhalers, and e-technology in asthma and COPD. Finally, future treatment strategies for better patient compliance such as personalized medicine and the importance of decision-making between patients and physicians were highlighted.

Challenges in nasal drug absorption: how far have we come?

The nasal route is commonly used for local delivery of drugs to treat inflammatory conditions. It is also an attractive route for systemic delivery of some drugs. Irrespective of intended use, administered drugs must permeate the epithelial or olfactory membrane to be effective. The enthusiasm for potential use of the nasal route for systemic drug delivery has not been met by comparable success. In this paper, the anatomical and physiological attributes of the nasal cavity and paranasal sinuses important for drug delivery and challenges limiting drug absorption are discussed. Efforts made so far in improving nasal drug absorption such as overcoming restrictive nasal geometry and paranasal sinuses accessibility, mucociliary clearance, absorption barriers, metabolism and drug physicochemical challenges are discussed. Highlights on future prospects of nasal drug delivery/absorption were discussed.

Effect of Cardiovascular Injury on Catabolism of Adenosine and Adenosine 5-'Triphosphate in Systemic Blood in a Freely Moving Rat Model In Vivo.

BACKGROUND: Previous studies have shown that catabolism of adenosine 5'-triphosphate (ATP) in red blood cell (RBC) may be a key factor for cardiovascular protection and maintaining cardiovascular homeostasis. OBJECTIVE: To investigate the effect of cardiovascular injury on adenosine and ATP catabolism in systemic blood using a freely moving rat model in vivo. METHOD: After acclimatized to the experimental environment, Sprague Dawley (SD) rats were each given either isoproterenol (30 mg/kg) or saline (1 mL/kg) by subcutaneous (sc) injection. Blood samples were collected sequentially for up to 6 hours for measurement of red blood cell (RBC) concentrations of adenine nucleotides and plasma concentrations of adenosine and its oxypurine metabolites. RESULTS: We have found isoproterenol induced 50% mortality under the experimental condition. Plasma concentrations of adenosine (ADO) and uric acid (UA) and red blood cell (RBC) concentrations of adenosine 5'-diphosphate (ADP) and adenosine 5'-monophosphate (AMP) in RBC were significantly higher in the isoproterenol treated rats (p < 0.05 for all the comparison). On the other hand, plasma concentrations of hypoxanthine (HYP) were higher in the control group (p < 0.05), but there was no statistically significant changes in ATP concentrations in the RBC (p > 0.05). CONCLUSION: Cardiovascular injury induced by isoproterenol resulted in breakdown of ATP to ADP and AMP in the RBC and also breakdown of ADO to UA in plasma and other tissues.

Organic cation rhodamines for screening organic cation transporters in early stages of drug development.

The aim of this study was to investigate the suitability of rhodamine-123, rhodamine-6G and rhodamine B as non-radioactive probes for characterizing organic cation transporters in respiratory cells. Fluorescent characteristics of the compounds were validated under standard in vitro drug transport conditions (buffers, pH, and light). Uptake/transport kinetics and intracellular accumulation of the compounds were investigated. Uptake/transport mechanisms were investigated by comparing the effect of pH, temperature, concentration, polarity, OCTs/OCTNs inhibitors/substrates, and metabolic inhibitors on the cationic dyes uptake in Calu-3 cells. Fluorescence stability and intensity of the compounds were altered by buffer composition, light, and pH. Uptake of the dyes was concentration-, temperature- and pH-dependent. OCTs/OCTNs inhibitors significantly reduced intracellular accumulation of the compounds. Whereas rhodamine-B uptake was sodium-dependent, pH had no effect on rhodamine-123 and rhodamine-6G uptake. Transport of the dyes across the cells was polarized: (AP→BL>BL→AP transport) and saturable: {Vmax=14.08±2.074, Km=1821±380.4 (rhodamine-B); Vmax=6.555±0.4106, Km=1353±130.4 (rhodamine-123) and Vmax=0.3056±0.01402, Km=702.9±60.97 (rhodamine-6G)}. The dyes were co-localized with MitoTracker®, the mitochondrial marker. Cationic rhodamines, especially rhodamine-B and rhodamine- 6G can be used as organic cation transporter substrates in respiratory cells. During such studies, buffer selection, pH and light exposure should be taken into consideration.

Thyroid hormone (levothyroxine) replacement via the respiratory route by inhalation: in vitro exploratory studies.

OBJECTIVES: To conduct proof of principle studies that will enable development of noninvasive (respiratory) delivery systems for levothyroxine (T4). METHODS: Preformulation (solubility, stability), formulation and biopharmaceutical (in vitro absorption, transport, gene expression) studies were conducted. Calu-3 cell line was used for permeation studies. RESULTS: Solubility profiles of T4 were established in aqueous (PBS, HBSS, isotonic saline) and non-aqueous solvents (PEG 400, PEG 600, propylene glycol, glycerine). Transport of the compound across Calu-3 cells suggested involvement of active transport systems. This correlated with expression of thyroxine transporters (MCT8, MCT10, OATP1A2, LAT1 and LAT2) in the cell line. Diffusion characteristics showed significant absorption with no detection of T4 metabolite (triiodothyronine). Formulation studies revealed that stable formulations could be prepared using a combination of aqueous and non-aqueous solvents. CONCLUSIONS: Results of the studies indicated that T4 can be absorbed effectively from the respiratory mucosa. Factors affecting stability such as pH and temperature should be taken into account during formulation development of this compound for the respiratory route.

Drug transporters in the nasal epithelium: an overview of strategies in targeted drug delivery.

In this article, we discussed the expression of some ABC (e.g., P-glycoprortein, MRP and CFTR) and SLC (e.g., POT, DAT, OAT, OATP, OCT, EAAT2/GLT1 and GLUT) amino acid, metal and nucleoside transporters in the nasal mucosa. The localization and therapeutic targeting of these transporters are explored in detail. The wide array of transporters discovered so far in the nasal mucosa implies that a plethora of compounds can be delivered by targeting these transporters. The article concludes with a discussion of the potential challenges and delivery options for transporter-mediated drug targeting via the nasal route.

Preliminary studies on validation of calu-3 cell line as a model for screening respiratory mucosa irritation and toxicity.

There is need to develop reproducible methods and experimental models for screening mucosal irritation and toxicity for drugs and pharmaceutical excipients. The aim of this study was to validate Calu-3 cell line as a model for screening respiratory irritation and toxicity of drugs and excipients. Eighteen test compounds were selected according to their irritation potential and European Centre for the Validation of Alternative Methods (ECVAM) guidelines. Cell toxicity and irritation was determined using MTT assay. Data analysis and interpretation were done using modified ECVAM approach; where replicate values met acceptance criteria if percent relative standard deviation (RSD) of the raw data is <18%. Compounds with mean relative viability values of 50% and below were classified as irritant (I); those above 50% were non-irritant (NI). At low concentration (0.2% w/v) and 1 h incubation, the Calu-3 cell culture model accurately predicted the toxicity of most test compounds. The specificity of our proposed model (percentage of in vivo non-irritants correctly predicted), concordance (percentage of compounds correctly predicted) and sensitivity (percentage of in vivo irritants correctly predicted) at 0.2% w/v and 60 min exposure were 100%, 72%, and 44%, respectively. In conclusion, the Calu-3 cell line in conjunction with MTT assay appears to be a potentially useful tool for screening drugs and excipients for respiratory mucosa irritation and toxicity. However, as the data reported in this study were solely based on MTT assay, additional studies are needed using other toxicity-/irritation-indicating methods to confirm the observed trend.

Drug-eluting nasal implants: formulation, characterization, clinical applications and challenges.

Chronic inflammation and infection of the nasal sinuses, also referred to as Chronic Rhinosinusitis (CRS), severely affects patients' quality of life. Adhesions, ostial stenosis, infection and inflammation relapses complicate chronic sinusitis treatment strategies. Drug-eluting stents, packings or implants have been suggested as reasonable alternatives for addressing these concerns. This article reviewed potential drug candidates for nasal implants, formulation methods/optimization and characterization methods. Clinical applications and important considerations were also addressed. Clinically-approved implants (Propel™ implant, the Relieva stratus™ MicroFlow spacer, and the Sinu-Foam™ spacer) for CRS treatment was an important focus. The advantages and limitations, as well as future considerations, challenges and the need for additional research in the field of nasal drug implant development, were discussed.

Organic cation transporters in human nasal primary culture: expression and functional activity.

BACKGROUND: The majority of drugs cross epithelial cells by either passive diffusion or via carrier-mediated drug transporters. The aim of this study was to investigate the transport characteristics, protein expression and localization of organic cation transporters in human nasal epithelium. METHODS & RESULTS: The expression, localization and transport characteristics of the transporters were investigated using permeation, PCR and immunohistochemistry. The uptake of 4-(4-(dimethylamino)styryl)-N-methylpyridinium iodide followed Michaelis-Menten kinetics. Its intracellular accumulation of the compound was inhibited by organic cation transporters (OCTs) and carnitine/organic cation transporter (OCTNs) inhibitors. Detected OCT1-3, OCTN1 and OCTN2 gene transcripts correlated with immunohistological staining for OCT1-3, OCTN1 and OCTN2 antibodies. Except for OCTN1, the antibodies were generally localized on the apical side of the epithelial cells. CONCLUSION: Based on the immunohistochemical and uptake/transport studies, we conclude that the human nasal epithelium expresses OCT1-3, OCTN1 and OCTN2 transporters mainly on the apical side of the nasal cells.

Characterization of Calu-3 cell monolayers as a model of bronchial epithelial transport: organic cation interaction studies.

BACKGROUND: To fully exploit organic cation transporters for targeted drug delivery in the lung, the use of a readily available and well-characterized tissue culture model and cheap easily detectable substrates is indispensable. OBJECTIVES: To investigate the suitability of Calu-3 as tissue model for characterizing organic cation permeation across the bronchial cells using a fluorescent dye, 4-(4-(Dimethylamino)styryl)-N-methylpyridinium iodide (4-DI-1-ASP). METHODS: Substrate uptake, inhibition, and transport were performed to establish active transport mechanism. Organic cation transporter expression was determined with quantitative polymerase chain reaction (qPCR), immune-histochemistry, and fluorescent microscopy. RESULTS: 4-Di-1-ASP uptake in Calu-3 cells was concentration (K(m) = 2.7 ± 0.3 mM, V(max) = 4.6 ± 2.6 nmol/µg protein/30 min), temperature (uptake at 37°C>>4°C), and pH dependent (higher uptake at pH ≥ 7). L-carnitine, verapamil, and corticosterone significantly inhibited its uptake with IC(50) of 28.2, 0.81, and 0.12 mM, respectively. Transport of the dye across the cells was polarized (AP→BL transport was 2.5-fold > BL→AP), saturable (Km = 43.9 ± 3.2) (µM; Vmax =0.0228 ± nmol/cm(2)/sec) and reduced 3-fold by metabolic inhibition. The expression pattern of the organic cation transporters (OCT) and carnitine/organic cation transporter (OCTN) isoforms was: OCT1<