Effect of viscosity on the pharmacokinetics and biological response to intranasal desmopressin

Formulation and investigation of differently charged β-cyclodextrin-based meloxicam potassium containing nasal powders

Nasal systemic drug delivery may provide an easy way to substitute parenteral or oral dosing, however, the excipients have an important role in nasal formulations to increase the permeability of the mucosa and prolong the residence time of the drug. In this work, we aimed to produce meloxicam potassium monohydrate (MXP) containing nasal powders by a nano spray drier with the use of a neutral, an anionic and a cationic β-cyclodextrin as permeation enhancers, and (polyvinyl)alcohol (PVA) as a water soluble polymer. The following examinations were performed in order to study the effect of the applied excipients on the nasal applicability of the formulations: laser scattering, scanning electron microscope measurement, XRPD, DSC and FTIR measurements, adhesivity, in vitro drug release and permeability tests through an artificial membrane and RPMI 2650 cells. Based on our results, spherical particles were prepared with a size of 1.89-2.21 µm in which MXP was present in an amorphous state. Secondary interactions were formed between the excipients and the drug. The charged cyclodextrin-based formulations showed significantly higher adhesive force values regardless of the presence of PVA. The drug release was fast and complete. The passive diffusion of MXP was influenced not only by the charge of the cyclodextrin, but the presence of PVA, too. The permeation of the drug was enhanced in the presence of the anionic cyclodextrin testing it on RPMI 2650 cell model.

Factors affecting nasal drug delivery and design strategies for intranasal drug delivery

Intranasal drug delivery system is a non-invasive drug delivery route with the advantages of no first-pass effect, rapid effect and brain targeting. It is a feasible alternative to drug delivery via injection, and a potential drug delivery route for the central nervous system. However, the nasal physiological environment is complex, and the nasal delivery system requires "integration of medicine and device". Its delivery efficiency is affected by many factors such as the features and formulations of drug, delivery devices and nasal cavity physiology. Some strategies have been designed to improve the solubility, stability, membrane permeability and nasal retention time of drugs. These include the use of prodrugs, adding enzyme inhibitors and absorption enhancers to preparations, and new drug carriers, which can eventually improve the efficiency of intranasal drug delivery. This article reviews recent publications and describes the above mentioned aspects and design strategies for nasal intranasal drug delivery systems to provide insights for the development of intranasal drug delivery systems.

Current understanding of nasal morphology and physiology as a drug delivery target

The nasal cavity is both a target for locally and systemically acting medications. An adequate treatment for rhinosinusitis continues to be an unmet need. With the recent approval of intranasal medications for the treatment of pain, the nasal cavity continues to be a viable route for rapid uptake into the systemic circulation. Despite the opportunities, there is still a void in the knowledge of how therapeutic entities interact with the nasal epithelium. In addition, new opportunities in mucosal immunity via nasal vaccination as well as the elusive nose to brain uptake continue to drive innovation. To facilitate understanding of the issues involved that facilitate drug delivery in the nose, a review of nasal morphology and physiology is presented.

Development, optimization and in vitro evaluation of alginate mucoadhesive microspheres of carvedilol for nasal delivery

The present research work was aimed at development and optimization of alginate mucoadhesive microspheres of carvedilol for nasal delivery to avoid first pass metabolism and to improve the therapeutic efficacy in the treatment of hypertension and angina pectoris. The microspheres were prepared by a water-in-oil (w/o) emulsification technique. A 2(3) factorial design was employed with drug : polymer ratio, calcium chloride concentration and cross-linking time as independent variables while particle size of the microspheres and in vitro mucoadhesion were the dependent variables. Regression analysis was performed to identify the best formulation conditions. Particle size was analysed by dynamic laser light diffraction technique and found to be in the range of 26.36-54.32 microm, which is favourable for intranasal absorption. The shape and surface characteristics were determined by scanning electron microscopy (SEM) which depicted the spherical nature and nearly smooth surfaces of the microspheres. The percentage encapsulation efficiency was found to be in the range between 36.62-56.18. In vitro mucoadhesion was performed by adhesion number using sheep nasal mucosa and was observed in a range from 69.25-85.28. Differential scanning calorimetry and X-ray diffraction results indicated a molecular level dispersion of carvedilol in the microspheres. In vitro release studies in pH 6.2 phosphate buffer indicated non-Fickian or anomalous type of transport for the release of carvedilol from the microspheres.

Polymers for mucoadhesive drug delivery system: a current status

To overcome the relatively short gastrointestinal (GI) time and improve localization for oral controlled or sustained release drug delivery systems, bioadhesive polymers that adhere to the mucin/epithelial surface are effective and lead to significant improvement in oral drug delivery. Improvements are also expected for other mucus-covered sites of drug administration. Bioadhesive polymers find application in the eye, nose, and vaginal cavity as well as in the GI tract, including the buccal cavity and rectum. This article lays emphasis mainly on mucoadhesive polymers, their properties, and their applications in buccal, ocular, nasal, and vaginal drug delivery systems with its evaluation methods.

Clinical study shows improved absorption of desmopressin with novel formulation

PURPOSE

To create improved pharmaceutical formulations for nasal and sublingual administration of desmopressin and investigate their pharmacokinetic profiles in comparison with a commercial nasal liquid spray and finally to evaluate the volunteers' opinions on the different dosage forms.

METHODS

Both formulations were based on the characteristics of interactive mixtures. The nasal powder spray was produced by a rotary evaporator technique with sodium starch glycolate as carrier material and the sublingual tablet by direct compression after dry mixing with mannitol as carrier. The clinical study was an open-label, randomised cross-over pharmacokinetic study in healthy volunteers.

RESULTS

The nasal powder formulation gave a threefold increase in the absorption, unaltered time to maximum plasma concentration and a tendency to lower variability in the amount absorbed compared with the liquid spray. The powder was reported to be more irritating than the liquid but was still well accepted by the volunteers. The tablet did not improve the uptake of desmopressin, likely because of a poor disintegration sublingually.

CONCLUSIONS

The nasal powder formulation is a promising new dosage form for the delivery of desmopressin and other compounds. The sublingual tablet has a beneficial means of production and may be further developed by decreasing its disintegration time.

Effect of chitosan structure properties and molecular weight on the intranasal absorption of tetramethylpyrazine phosphate in rats

The objective of this work was to assess and compare the absorption promoting effect of different molecular-weight chitosans, trimethyl chitosans and thiolated chitosans for intranasal absorption of 2,3,5,6-tetramethylpyrazine phosphate (TMPP). An in situ nasal perfusion technique in rats was utilized to test the rate and extent of TMPP absorption in situ. In vivo studies were carried out in rats and the pharmacokinetic parameters were calculated and compared with that of intravenous injection. All the chitosan derivatives investigated could enhance the intranasal absorption of TMPP significantly. However, thiolation could not improve the absorption-enhancing capacity of chitosan remarkably even when the thiolation ratio was as high as 152 micromol/g. In contrast, trimethylated chitosan exhibited stronger absorption-enhancing ability than the homopolymer chitosan. The permeation enhancing effect of chitosan increased with increasing molecular weight up to M(w) 100 kDa. In vivo studies indicated that chitosan 100 kDa and TMC 50 kDa had comparable absorption-enhancing effect but chitosan 100 kDa functioned for more than 120 min versus 90 min for TMC. A good correlation was found between the in situ absorption data and plasma concentration in vivo for the polymers investigated. This study demonstrated that both chitosan structural features and chitosan molecular weight play a key role on promoting the intranasal absorption of TMPP. Taking safety reason into account, chitosan 100 kDa is the most promising as an intranasal absorption enhancer.

Pharmacodynamics and potential toxicity of intranasally administered dipyrone

Dipyrone is a non-narcotic analgesic and antipyretic drug used in both pediatric and adult patients. Dipyrone solution can be used intranasally as an antipyretic agent for infants. However, dipyrone is not stable in liquid state. Therefore, a stable dipyrone formulation was developed and the antipyretic effect of the formulation was studied after intranasal administration in rabbits and rats, respectively. To guarantee dose accuracy in animal studies, effect of dose volume on the distribution of dipyrone solution in rabbit nasal cavities were studied, using gentian violet as an indicator. Animal fever model and intranasal administration methods were established. In addition, the potential toxicity of the dipyrone formulation was studied. It was shown that the nasal volume of rabbits is large enough to hold 100 microl solution. After intranasal administration, improved pharmacodynamics was obtained with the new developed dipyrone formulation compared to the normal dipyrone solution, and significantly decreased body temperature was observed 10 min after dosing. The toxicity was negligible. In conclusion, the dipyrone formulation is effective and safe for clinical medication.

Rapid-onset intranasal delivery of metoclopramide hydrochloride. Part I. Influence of formulation variables on drug absorption in anesthetized rats

Intranasal (IN) administration is a promising approach for rapid-onset delivery of medications and to circumvent their first-pass elimination when taken orally. Metoclopramide (MCP) is a potent antiemetic, effective even for preventing emesis induced by cancer chemotherapy. The feasibility of developing an efficacious intranasal formulation of metoclopramide has been undertaken in this study. The nasal absorption of MCP was studied in anesthetized rats over 60min using the in vivo in situ technique. The influence of several formulation variables, vis., pH and the addition of preservative, viscosity and absorption enhancing agents on the nasal MCP absorption was examined. The data obtained showed that MCP was well absorbed nasally where almost 90% of the drug was absorbed after 60min from the rat nasal cavity. The MCP absorption was pH-dependant such that the apparent first-order rate constant of absorption (K(app)) was almost tripled when the pH of the solution was increased from 5 to 8. However, deviation from the classical pH-partition theory was observed pointing to the role of aqueous pore pathway in MCP nasal absorption. The K(app) was significantly increased (P<0.05) by incorporation of 0.01% of the preservative benzalkonium chloride. Conversely, increasing the solution viscosity by the use of hydroxylpropyl methylcellulose adversely affected the rate of absorption. The use of enhancers namely sodium deoxycholate, sodium cholate, chitosan low and high molecular weight, protamine sulphate and poly-l-arginine resulted in significant increase in MCP absorption. The highest promoting effect was observed with the bile salt sodium deoxycholate where about 92% of the drug was absorbed in 25min from the rat nasal cavity and the K(app) showed more than two-fold increase as compared to control (from 0.0452 to 0.1017min(-1)).

The influence of gellan gum on the transfer of fluorescein dextran across rat nasal epithelium in vivo

The nasal uptake of a 3000 Da fluorescein dextran (FD3) was investigated in rats, using fluorescence microscopy. The uptake from a formulation containing deacetylated gellan gum, an in situ gelling agent, was compared to that from a mannitol solution. Additionally, the rheological behavior of the gellan gum in water and saline was studied. It was shown that the gellan gum solution was easily administered owing to its low viscosity, and upon contact with the mucosa, a gel was formed. The epithelial uptake and transfer of FD3 appeared to be increased and prolonged using the gellan gum formulation. This increase was not accompanied by qualitative changes of the epithelial FD3 distribution or any visible harmful effects.

An effective absorption behavior of insulin for diabetic treatment following intranasal delivery using porous spherical calcium carbonate in monkeys and healthy human volunteers

Porous spherical calcium carbonate (PS-CaCO(3)), in contrast to regular calcium carbonate (CaCO(3)), which has a cuboidal particle shape, has a characteristic spherical particle shape with a large number of porous, sliver crystals. The effect of PS-CaCO(3) as a drug carrier on intranasal insulin absorption was investigated in cynomolgus monkeys and healthy human volunteers. Each insulin formulation (powder) containing PS-CaCO(3) or regular CaCO(3) was administered intranasally. Serum insulin and glucose levels after administration were evaluated. The insulin absorption after intranasal administration with each CaCO(3) was found to be much more rapid than that after subcutaneous administration. The serum insulin level after intranasal insulin delivery (16 U per monkey) with PS-CaCO(3) showed a higher C(max) (403.5 microU/mL) and shorter T(max) (0.167 h) when compared with regular CaCO(3). The serum glucose level reduction rate after intranasal delivery using PS-CaCO(3) was faster than that of regular CaCO(3), reflecting the difference in absorption rates. Following repeated intranasal administrations for 4 weeks in monkeys, no toxicity was observed even with a maximum insulin dose level of 25 U. Furthermore, the intranasal insulin absorption rate with PS-CaCO(3) in healthy humans was also observed to be considerably faster than that with regular CaCO(3). Effects of PS-CaCO(3) on a more effective absorption behavior of insulin were considered to be the result of a greater affinity between the nasal mucosa layer and PS-CaCO(3), which is closely related to its structural characteristics. Thus, intranasal insulin delivery using PS-CaCO(3) is thought to be a safe and highly available system enabling more effective insulin absorption behavior with the appearance of endogenous postprandial insulin secretion in healthy humans. We believe that our intranasal insulin delivery system enabling a rapid and short-acting pharmacological effect against postprandial hyperglycemia will be more beneficial than pulmonary insulin delivery systems in the treatment of diabetes.

Preparation of desmopressin-containing liposomes for intranasal delivery

The loading and leakage characteristics of the desmopressin-containing liposomes and the effect of liposomes on the nasal mucosa permeation and antidiuresis of desmopressin were investigated. Higher loading efficiency of desmopressin for positively charged liposomes than negatively charged liposomes was obtained, and neutral liposomes resulted in a similar loading efficiency as that of positively charged liposomes. Greater leakage of desmopressin from negatively charged liposomes than from positively charged and neutral liposomes was shown. The increase of permeability of desmopressin through the nasal mucosa indicated positively charged liposomes>negatively charged liposomes>solution. It was suggested that the enhanced contact time of positively charged liposomes with negatively charged nasal mucosa led to a high local desmopressin concentration on the penetration site to promote an effective penetration of desmopressin through the nasal mucosa. The desmopressin antidiuresis result after intranasal administration was in good agreement with the permeability result in the order of positively charged liposomes>negatively charged liposomes>solution. One of the mechanisms for the explanation of the best result on the enhancement of antidiuresis for positively charged liposomes may be the bioadhesive effect of the liposomes on the negatively charged nasal mucosa.

The biopharmaceutical aspects of nasal mucoadhesive drug delivery

Nasal drug administration has frequently been proposed as the most feasible alternative to parenteral injections. This is due to the high permeability of the nasal epithelium, allowing a higher molecular mass cut-off at approximately 1000 Da, and the rapid drug absorption rate with plasma drug profiles sometimes almost identical to those from intravenous injections. Despite the potential of nasal drug delivery, it has a number of limitations. In this review, the anatomy and physiology of the nasal cavity, as well as ciliary beating and mucociliary clearance as they relate to nasal drug absorption, are introduced. The rationale for nasal drug delivery and its limitations, some factors that influence nasal drug absorption, and the experimental models used in nasal drug delivery research are also reviewed. Nasal mucoadhesion as a promising method of nasal absorption enhancement is discussed, and factors that influence mucoadhesion, as well as safety of nasal mucoadhesive drug delivery systems are reviewed in detail. Nasal drug administration is presently mostly used for local therapies within the nasal cavity. Anti-allergic drugs and nasal decongestants are the most common examples. However, nasal drug administration for systemic effects has been practised since ancient times. Nasally-administered psychotropic drugs by native Americans, the use of tobacco snuffs, and nasal administration of illicit drugs such as cocaine are all well known (Illum & Davis 1992). Nowadays, the nasal cavity is being actively explored for systemic administration of other therapeutic agents, particularly peptides and proteins (Illum 1992; Edman & Björk 1992), as well as for immunization purposes (Lemoine et al 1998). To better understand the basis for nasal drug absorption and factors that can influence it, a brief review of the anatomy and physiology of the nose is appropriate.

Development and evaluation of nasal formulations of ketorolac

Ketorolac tromethamine is a potent non-narcotic analgesic with moderate anti-inflammatory activity. Clinical studies indicate that ketorolac has a single dose efficacy greater than morphine for postoperative pain and has excellent applicability in the emergency treatment of pain. Due to incomplete oral absorption of ketorolac, several approaches have been tried to develop a nonoral formulation in addition to injections, especially for the treatment of migraine headache. The aim of our study was to develop a nasal formulation of ketorolac with a dose equivalent to the oral formulation. A series of spray and lyophilized powder formulations of ketorolac were administered into the nasal cavity of rabbits, and their pharmacokinetics profiles were assessed. The spray and powder formulations were compared through their pharmacokinetics parameters and absolute bioavailability. Drug plasma concentration was determined using solid phase extraction, followed by an HPLC analysis. Nasal spray formulations were significantly better absorbed than powder formulations. A nasal spray formulation of ketorolac tromethamine showed the highest absorption with an absolute bioavailability of 91%. Within 30 min of administration, the plasma concentration was comparable to that resulting from an intravenous injection. The absolute bioavailability of a solution of ketorolac acid was 70%. Apparently, the dissolution of ketorolac acid into the mucous layer limits its absorption. There were no significant differences in absorption between different powder formulations. Even the reduction of particle size from 123 microm to 63 microm did not indicate better absorption of ketorolac tromethamine from powder formulations. Interestingly, the absolute bioavailability of ketorolac tromethamine from a powder formulation is only 38%, indicating that the drug may not be totally released from the polymer matrix before it is removed from nasal epithelium by mucociliary clearance.

Nasal mucoadhesive delivery systems of the anti-parkinsonian drug, apomorphine: influence of drug-loading on in vitro and in vivo release in rabbits

Lyophilized polyacrylic acid powder formulations loaded with apomorphine HCl were prepared and the influence of drug loading on in vitro release and in vivo absorption studied after intranasal administration in rabbits. These formulations prepared with Carbopol 971P, Carbopol 974P and polycarbophil sustained apomorphine release both in vitro and in vivo. The in vitro release rate and mechanism were both influenced by the drug loading. There was no large influence of drug loading on the time to achieve the peak (Tmax) for a particular polymer, but Tmax differed between different polymers. For a particular drug loading, the Tmax from Carbopol 971P was the slowest compared with that for Carbopol 974P and polycarbophil; however, only the Tmax from Carbopol 971P loaded with 15% w/w of apomorphine was significantly longer than polycarbophil of similar drug loading (P=0.0386). The trend further observed was that increasing drug loading led to increased peak plasma concentration and area under the curve (AUC). In the second part of this study, a mixture containing an immediate release component and sustained release formulation was administered in an attempt to increase the initial plasma level, as this could be therapeutically beneficial. Only one peak plasma concentration was observed and the initial plasma concentrations were no higher than those obtained with solely sustained release formulation. The Tmax, the peak plasma drug concentration (Cmax) and AUC from the lactose-containing formulation were lower than the formulation without lactose but the differences were only marginally statistically significant for Cmax (P=0.0911) and AUC (P=0.0668), but not Tmax (P=0.2788).

Intranasal insulin delivery and therapy

Intranasal insulin delivery has been widely investigated as an alternative to subcutaneous injection for the treatment of diabetes. The pharmacokinetic profile of intranasal insulin is similar to that obtained by intravenous injection and, in contrast to subcutaneous insulin delivery, bears close resemblance to the 'pulsatile' pattern of endogenous insulin secretion during meal-times. The literature suggests that intranasal insulin therapy has considerable potential for controlling post-prandial hyperglycaemia in the treatment of both IDDM and NIDDM. However, effective insulin absorption via the nasal route is unlikely without employing the help of absorption enhancers or promoters which are able to modulate nasal epithelial permeability to insulin and/or prolong the residence time of the drug formulation in the nasal cavity. This article discusses the structure and function of the nasal cavity, the barriers which prevent nasal insulin absorption and through the use of absorption enhancers or promoters methods by which these barriers may be overcome.

Nasal mucociliary clearance as a factor in nasal drug delivery

The nasal mucociliary clearance system transports the mucus layer that covers the nasal epithelium towards the nasopharynx by ciliary beating. Its function is to protect the respiratory system from damage by inhaled substances. Impairment of nasal mucociliary clearance can result in diseases of the upper airways. Therefore, it is important to study the effects of drugs and drug excipients on nasal mucociliary clearance. A large number of methods are used to assess mucociliary clearance. These methods study the effects of drug and excipients on the mucociliary system in vitro or in vivo in animals and humans. In some cases, the results of different in vitro and in vivo measurements do not correlate well. In vitro methods, especially ciliary beat frequency measurements, have been demonstrated to be valuable tools for toxicity screening. However, in vivo studies are essential to confirm the safety of nasal drug formulations. Nasal mucociliary clearance also has implications for nasal drug absorption. Drugs are cleared rapidly from the nasal cavity after intranasal administration, resulting in fast systemic drug absorption. Several approaches are discussed to increase the residence time of drug formulations in the nasal cavity, resulting in improved nasal drug absorption. However, more experimental evidence is needed to support the conclusion that this improved absorption is caused by a longer residence time of the nasal drug formulation.

Systemic effects of two nasally administered glucocorticosteroids

Two topical corticosteroids, budesonide (BUD) and beclomethasone dipropionate (BDP), both administered as suspensions in water, were investigated in healthy volunteers regarding influence on cortisol in plasma and urine (U-cortisol) after nasal application. In the first study, single doses of 200, 400, and 800 micrograms of BDP and BUD were given at 10:00 pm. In the second study, 100, 200, and 400 micrograms were given mornings and evenings for 4 days. In the single-dose study, none of the drugs or doses showed any significant influence on cortisol in plasma. However, U-cortisol decreased significantly after BUD 400 and 800 micrograms. In the multidose study, U-cortisol values were significantly reduced after all doses of BUD and the highest dose of BDP. The compounds tested showed different ability to cause measurable systemic effects after nasal application. The clinical implication is that the prescriber, when choosing a compound, should take the application site into consideration and should also be encouraged to find the lowest effective dose.

Minimizing systemic absorption of topically administered ophthalmic drugs

Due to absorption several ocularly applied medications give rise to systemic side-effects. The problem of systemic drug absorption should be taken into account in designing ocular drug and dosage forms so that oculospecificity of the medications is optimized. In this review we summarize the current knowledge about the systemic absorption of ocularly applied topical drugs. Special emphasis is directed to the methods that can be used to minimize systemic absorption and increase the oculospecificity of drugs, e.g., reducing volume and increasing viscosity of eyedrops, controlling drug release from depot preparations, prodrug-derivatization, and addition of vasoconstrictive agents.

The nasal mucociliary clearance: relevance to nasal drug delivery

Mucociliary clearance is an important physiological defense mechanism of the respiratory tract to protect the body against noxious inhaled materials. This process is responsible for the rapid clearance of nasally administered drugs from the nasal cavity to the nasopharynx, thereby interfering with the absorption of drugs following intranasal application. This review describes the mucociliary system and the methods used for its characterization. Examples are given of the effects of drugs and additives on its functioning. Further, possible approaches are presented for increasing the residence time of drugs in the nasal cavity, thereby improving intranasal drug delivery.

Nasal absorption enhancement of 17 beta-estradiol by dimethyl-beta-cyclodextrin in rabbits and rats

A new formulation for nasal administration containing 17 beta-estradiol (E2) with dimethyl-beta-cyclodextrin (DM beta C) as a solubilizer and absorption enhancer is described. Nasal administration of this E2-DM beta C formulation gave a significantly higher E2 absorption than an E2 suspension in both rabbits and rats. Relative to an intravenous injection of the E2-DM beta C formulation, absolute bioavailabilities of 94.6 and 67.2% were calculated for the nasal E2-DM beta C formulation in rabbits and rats, respectively. Differences in bioavailability may have resulted from differences in experimental animal conditions. The effects on human nasal ciliary activity of the E2-DM beta C formulation were studied with an in vitro method. The formulation was found to exert only a minor effect on ciliary beat frequency. Thus, nasal delivery of E2, using a cyclodextrin inclusion formulation, may have potential for clinical application, e.g., in the therapy of postmenopausal disorders.

Transport of peptide and protein drugs across biological membranes

The transport characteristics of peptide and proteins drugs across various epithelial membrane barriers are outlines. These include transport through the intestinal, buccal, nasal and pulmonary absorptive mucosae, as well as transdermal penetration. Because peptides and proteins are hydrophilic and high molecular weight compounds, they commonly show minor permeability across the mentioned biological membranes. In order to improve their transport properties and thereby their systemic bioavailability, several strategies can be undertaken, such as the synthesis of stabilized and lipophilic analogues, the application of absorption enhancers and protease inhibitors, and the design of suitable dosage forms (e.g., liposomes, biodegradable nanocapsules, bioadhesive microspheres).