Enhancement of Nasal Salmon Calcitonin Absorption by Lauroylcarnitine Chloride in Rats

Purpose. We investigated optimum formulation characteristics in the nasal absorption of salmon calcitonin (sCT) by incorporation of acylcarnitines. Methods. Nasal sCT formulations were administered to anesthetized rats. Plasma calcium level was measured and pharmacological bioavailability (P.bioav) was calculated. Results. Nasal sCT absorption was significantly enhanced by carnitines with acyl groups of 12 or more carbon atoms. Enhancement by lauroylcarnitine chloride (LCC) was observed at its critical micelle concentration and reached a plateau at the concentration of 0.1%. Optimal absorption was achieved at a molar ratio of LCC to sCT of 5:1. Enhancement was not influenced by osmolarity and maximum enhancement was obtained at pHs 3.1 and 4.0. Conclusions. The 12-carbon LCC was the strongest enhancer among acylcarnitines. Micelle formation played a key role in this enhancement effect.     

Effects of pH and Dose on Nasal Absorption of Scopolamine Hydrobromide in Human Subjects

Purpose. The present study was conducted to evaluate theeffects of formulation pH and dose on nasal absorption of scopolaminehydrobromide, the single most effective drug available for the prevention ofnausea and vomiting induced by motion sickness. Methods. Human subjects received scopolamine nasally at adose of 0.2 mg/0.05 mL or 0.4 mg/0.10 mL, blood samples were collected atdifferent time points, and plasma scopolamine concentrations were determinedby LC-MS/MS. Results. Following administration of a 0.2 mg dose, theaverage C_max values were found to be 262 ± 118, 419± 161, and 488 ± 331 pg/mL for pH 4.0, 7.0, and 9.0formulations, respectively. At the 0.4 mg dose the average C_maxvalues were found to be 503 ± 199, 933 ± 449, and 1,308± 473 pg/mL for pH 4.0, 7.0, and 9.0 formulations, respectively. At a0.2 mg dose, the AUC values were found to be 23,208 ± 6,824, 29,145± 9,225, and 25,721 ± 5,294 pg.min/mL for formulation pH 4.0,7.0, and 9.0, respectively. At a 0.4 mg dose, the average AUC value wasfound to be high for pH 9.0 formulation (70,740 ± 29,381 pg.min/mL)as compared to those of pH 4.0 (59,573 ± 13,700 pg.min/mL) and pH 7.0(55,298 ± 17,305 pg.min/mL) formulations. Both the C_maxand AUC values were almost doubled with doubling the dose. On the otherhand, the average T_max values decreased linearly with a decreasein formulation pH at both doses. For example, at a 0.4 mg dose, the averageT_max values were 26.7 ± 5.8, 15.0 ± 10.0, and 8.8± 2.5 minutes at formulation pH 4.0, 7.0, and 9.0, respectively. Conclusions. Nasal absorption of scopolamine hydrobromidein human subjects increased substantially with increases in formulation pHand dose.     

Metabolism of Azetirelin,a New Thyrotropin-releasing Hormone (TRH) Analogue,by Intestinal Microorganisms

Purpose. We evaluated the effect of luminal bacterial metabolism on intestinal absorption of azetirelin in rats. In vitro characteristics of bacterial metabolism of azetirelin were also investigated with the goal of overcoming the low stability of the peptidic drug against luminal microorganisms. Methods. Plasma azetirelin levels after oral administration to antibiotic-pretreated rats was examined. In vitro incubation experiments with bacterial suspensions were also performed to clarify the location of azetirelin breakdown activity as well as the effects of oxygen, pH, and various protease inhibitors on drug metabolism. Results. Plasma azetirelin levels were sustained after oral administration to antibiotic-treated rats. Incubation with rat luminal contents demonstrated that azetirelin was metabolized by anaerobic bacteria, which are predominant in the distal intestine. Fecal suspensions from rats, dogs, and humans showed comparable metabolic activity. Azetirelin breakdown in the bacterial suspension was pH-dependent and was inhibited in the presence of bacitracin or puromycin. Conclusions. Bacterial metabolism influences the degree of absorption of azetirelin in the distal intestine. Control of the luminal pH environment may be a practical method for improving the stability of azetirelin against intestinal microorganisms.     

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 θ m to 63 θ m 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 absorption kinetics of human growth hormone enhanced by acylcarnitines in rats

Pharmacokinetic analysis revealed that acylcarnitines enhanced overall nasal absorption of human growth hormone (HGH) in rats. Acylcarnitines dramatically shortened onset time, shortened absorption-duration time, and efficiently delivered HGH. HGH administered intranasally with acylcarnitines appeared in the blood within 0.28–2.7 min, far more rapidly than the 11.7 min after intranasal administration of HGH without acylcarnitines (CTL) or the 9.8 min after subcutaneous administration (SC). Absorption-duration times of HGH enhanced by acylcarnitines were in the range of 2.1–3.8 h, which are shorter than those of CTL (7.5 h) or SC (9.8 h). Among acylcarnitines at 1%, lauroylcarnitine chloride (LCC) showed the greatest absolute bioavailability (17.4%), which is 0.73 times the absolute bioavailability value for SC (22.1%). LCC enhancement reached a plateau at a concentration of 0.1%. This nasal absorption enhancement would be suitable for pulsatile administration. A single dose toxicity study also suggested that LCC had similar systemic safety to L-carnitine at a high dose of 100 mg/kg in mice. Further, the potential safety of LCC was ten times greater than palmitoylcarnitine chloride.     

Enhancement of Nasal Delivery of a Renin Inhibitor in the Rat Using Emulsion Formulations

Nasal absorption of O-(N-morpholino-carbonyl-3-L-phenylaspartyl-L-leucinamide of (2S,3R,4S)-2-amino-1-cyclohexyl-3,4-dihydroxy-6-methylheptane (I), a renin inhibitor, was evaluated in two rat nasal models, one involving surgery and the other requiring no surgical intervention. Oleic acid/monoolein emulsion formulations were tested along with a control PEG 400 solution. The percent absolute bioavailability of the compound was enhanced from 3–6% (PEG 400 solution) to 15–27% when the emulsion formulations were used. The different nasal model techniques (with and without surgery) did not produce any statistical difference in the absolute bioavailability values for I. Emulsion formulations did not produce appreciable damage as assessed morphologically. It is suggested that emulsion formulations containing membrane adjuvants such as oleic acid and monoolein can be used to enhance the nasal delivery of low-bioavailable, lipid-soluble drugs.____________________     

Nasal Delivery of Insulin Using Novel Chitosan Based Formulations: A Comparative Study in Two Animal Models Between Simple Chitosan Formulations and Chitosan Nanoparticles

Purpose. To investigate whether the widely accepted advantages associated with the use of chitosan as a nasal drug delivery system, might be further improved by application of chitosan formulated as nanoparticles. Methods. Insulin-chitosan nanoparticles were prepared by the ionotropic gelation of chitosan glutamate and tripolyphosphate pentasodium and by simple complexation of insulin and chitosan. The nasal absorption of insulin after administration in chitosan nanoparticle formulations and in chitosan solution and powder formulations was evaluated in anaesthetised rats and/or in conscious sheep. Results. Insulin-chitosan nanoparticle formulations produced a pharmacological response in the two animal models, although in both cases the response in terms of lowering the blood glucose levels was less (to 52.9 or 59.7% of basal level in the rat, 72.6% in the sheep) than that of the nasal insulin chitosan solution formulation (40.1% in the rat, 53.0% in the sheep). The insulin-chitosan solution formulation was found to be significantly more effective than the complex and nanoparticle formulations. The hypoglycaemic response of the rat to the administration of post-loaded insulin-chitosan nanoparticles and insulin-loaded chitosan nanoparticles was comparable. As shown in the sheep model, the most effective chitosan formulation for nasal insulin absorption was a chitosan powder delivery system with a bioavailability of 17.0% as compared to 1.3% and 3.6% for the chitosan nanoparticles and chitosan solution formulations, respectively. Conclusion. It was shown conclusively that chitosan nanoparticles did not improve the absorption enhancing effect of chitosan in solution or powder form and that chitosan powder was the most effective formulation for nasal delivery of insulin in the sheep model.     

Insoluble Powder Formulation as an Effective Nasal Drug Delivery System

Purpose. To evaluate the utility of insoluble powder formulation for nasal systemic drug delivery. Methods. To compare the efficacy of liquid and powder formulations, the nasal absorption of drugs was examined in rats using hydrophilic compounds with various molecular weights (MW) such as phenol red, cyanocobalamin, and fluorescein isothiocyanate (FITC)-Dextrans, and several kinds of powder. Intranasal residence time was also compared among the different formulations. Results. All the drugs examined were absorbed through the nasal mucosa to varying extent; their systemic bioavailability decreased with increasing MW. Insoluble calcium carbonate (CaCO₃) powder formulation provided increased absorption of drugs over the wide range of MW from 354 to 77,000 Da. In the case of phenol red, intranasal administration as a CaCO₃ powder formulation resulted in a plasma concentration profile similar to that of an intravenous bolus dose due to its very rapid and complete absorption from the nasal cavity. Furthermore, improved bioavailability of FITC-Dextran (MW 4,400; FD-4) was also achieved with other insoluble powders as well as CaCO₃, but not with soluble powders such as lactose, d-sorbitol, and d-mannitol. Insoluble powder formulation prolonged the residence time of FD-4 within the nasal cavity. Conclusions. Insoluble powder formulations improve nasal bioavailability predominantly by retarding drug elimination from the absorption site and appear to be effective for nasal systemic drug delivery.     

Impact of Regional Intestinal pH Modulation on Absorption of Peptide Drugs: Oral Absorption Studies of Salmon Calcitonin in Beagle Dogs

Purpose. To investigate the relationship between the modulation of intestinal pH and the oral absorption properties of a model peptide drug, salmon calcitonin (sCT), in conscious beagle dogs. Methods. Studies were performed to characterize the disintegration of the formulation, intestinal pH changes, and the appearance of the peptide in the blood. Enteric-coated formulations containing sCT and various amounts of citric acid (CA) were tethered to a Heidelberg capsule (HC) and given orally to normal beagle dogs. Blood samples were collected and analyzed by radioimmunoassay (RIA). Intestinal pH was continuously monitored using the Heidelberg pH capsule (HC) system. The integrity of the HC-delivery system tether was verified by fluoroscopy. Results. The intra-individual variation in gastric emptying (GE) of the delivery system was large. There were also large inter-individual differences in the disintegration and absorption properties of the various formulations. However, the peak plasma concentrations of sCT were always observed when the intestinal pH declined. The average baseline intestinal pH was 6.1 ± 0.2 (mean ± SEM, n = 12). The intestinal pH reduction was 2.6 ± 0.4 (mean ± SEM, n = 12, ranged from 0.5 to 4.0 units from baseline). There was a good correlation between the time to reach the trough intestinal pH (t_pH,min) and time to reach the peak plasma concentration (t_conc,max) of sCT (t_conc,max = 0.95 × t_pH,min + 14.1, n = 11, r² = 0.91). Plasma C_max and area under the curve (AUC) increased with increasing amounts of CA in the formulations. Conclusions. The results of these studies demonstrate that the oral absorption properties of a model peptide drug, sCT, can be modulated by changing intestinal pH. sCT is a substrate for the pancreatic serine protease trypsin which has maximal activity at pH 5 to 6. Reducing intestinal pH presumably stabilizes sCT in the GI tract enabling greater absorption of the intact peptide.     

Effect of Glass Transition Temperature on the Stability of Lyophilized Formulations Containing a Chimeric Therapeutic Monoclonal Antibody

Purpose. The purpose of this study is to highlight the importance of knowing the glass transition temperature, T_g, of a lyophilized amorphous solid composed primarily of a sugar and a protein in the interpretation of accelerated stability data. Methods. Glass transition temperatures were measured using DSC and dielectric relaxation spectroscopy. Aggregation of protein in the solid state was monitored using size-exclusion chromatography. Results. Sucrose formulation (T_g ~ 59°C) when stored at 60°C was found to undergo significant aggregation, while the trehalose formulation (T_g ~ 80°C) was stable at 60°C. The instability observed with sucrose formulation at 60°C can be attributed to its T_g (~59°C) being close to the testing temperature. Increase in the protein/sugar ratio was found to increase the T_gs of the formulations containing sucrose or trehalose, but to different degrees. Conclusions. Since the formulations exist in glassy state during their shelf-life, accelerated stability data generated in the glassy state (40°C) is perhaps a better predictor of the relative stability of formulations than the data generated at a higher temperature (60°C) where one formulation is in the glassy state while the other is near or above its T_g.     

A Semisynthetic Quillaja Saponin as a Drug Delivery Agent for Aminoglycoside Antibiotics

Purpose. The purpose of this study was to investigate the utility of a purified, semisynthetic saponin, DS-1, prepared by deacylation of a naturally occurring saponin from the bark of the Quillaja saponaria Molina tree, as a permeation enhancer for mucosal delivery of the aminoglycosides, gentamicin and tobramycin. Methods. Gentamicin or tobramycin formulations, with and without DS-1, were administered to rats nasally, ocularly, and rectally. Serum aminoglycoside levels following mucosal application were compared with those administered intramuscularly. Gentamicin formulations, with and without DS-1, were administered intranasally to mice 60 minutes after a lethal bacterial challenge. To ascertain nasal irritation potential, DS-1 nosedrops were administered to rats twice daily for 7 days in the right nostril only. Comparison of the left (internal control) and right nostril was made with a control group that received only buffer. Results. Significant transport across mucous membranes was only observed in formulations containing DS-1. This effect on drug delivery was transient. Administration of an intranasal gentamicin/ DS-1 formulation reversed the lethal bacterial challenge in mice, demonstrating that biological activity was retained after absorption. Nasal irritation was not observed in groups receiving DS-1 nose-drops, which were identical to control groups. Conclusions. DS-1 has potential as a transmucosal delivery agent for the aminoglycoside antibiotics.     

Mutual Inhibition of the Insulin Absorption-Enhancing Properties of Dodecylmaltoside and Dimethyl-β-cyclodextrin Following Nasal Administration

Purpose. To determine if a nasal insulin formulation containing two distinct absorption–enhancing agents exhibits an additive or synergistic increase in the rate of systemic insulin absorption. Methods. The pharmacokinetics and pharmacodynamics of insulin absorption were measured in hyperglycemic anesthetized rats following nasal insulin administration with formulations containing two different types of absorption–promoting agents, dimethyl––cyclodextrin (DMBCD) and dodecylmaltoside (DDM). Results. When either DDM (0.1–0.5%) or DMBCD (1.0–5.0%) was added to the nasal insulin formulation, a significant and rapid increase in plasma insulin levels was observed, with a concomitant decrease in blood glucose concentration. A combined preparation containing 0.25% DDM (0.005 M) and 2.5% DMBCD (0.019M), however, failed to cause an increase in plasma insulin levels or a decrease in blood glucose concentration. Increasing concentrations of DDM added to an insulin formulation with a fixed DMBCD concentration caused a decrease, rather than an increase, in systemic absorption of insulin. Conclusions. Mixing DMBCD and DDM resulted in mutual inhibition of their ability to enhance systemic absorption of insulin following nasal delivery. The results are consistent with the formation of an inclusion complex between DDM and DMBCD which lacks the ability to enhance nasal insulin absorption.     

Effect of Formulation Additives upon the Intranasal Bioavailability of a Peptide Drug: Tetracosactide (ACTH1−24)

Nasal absorption of tetracosactide (ACTH_1–24; Synacthen) was evaluated in anesthetized rats and compared to intravenous and intramuscular (i.m.) administration. The effect of formulation additives on tetracosactide bioavailability was studied following modification of nasal saline solution. Poloxamer 407 (Pluronic F-127) was used as a vehicle for drug sustained release, whereas sodium glycocholate and bacitracin were used as enhancers. Tetracosactide plasma levels were monitored with radioimmunoassay. Nasal bioavailability was low (4.4%) compared to i.m. (24%). Poloxamer 407 addition did not improve drug kinetics profiles and showed a nonsignificant decrease in bioavailability (4%). On the other hand, both enhancers effectively increased tetracosactide nasal absorption. The sodium glycocholate effect was very fast (T _max = 5 min), but did not last long. Moreover, absorption was increased threefold compared to the simple formulation. On the other hand, maximum tetracosactide levels in plasma were reached after 15 min for the formulation containing bacitracin as enhancer, and tetracosactide bioavailability was strongly increased, to 24%, i.e., as much as after an i.m. injection.     

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 θ m to 63 θ m 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.     

The Stability of Recombinant Human Growth Hormone in Poly(lactic-co-glycolic acid) (PLGA) Microspheres

Purpose. The development of a sustained release formulation for recombinant human growth hormone (rhGH) as well as other proteins requires that the protein be stable at physiological conditions during its in vivo lifetime. Poly(lactic-co-glycolic acid) (PLGA) microspheres may provide an excellent sustained release formulation for proteins, if protein stability can be maintained. Methods. rhGH was encapsulated in PLGA microspheres using a double emulsion process. Protein released from the microspheres was assessed by several chromatrographic assays, circular dichroism, and a cell-based bioassay. The rates of aggregation, oxidation, diketopiperazine formation, and deamidation were then determined for rhGH released from PLGA microspheres and rhGH in solution (control) during incubation in isotonic buffer, pH 7.4 and 37°C. Results. rhGH PLGA formulations were produced with a low initial burst (<20%) and a continuous release of rhGH for 30 days. rhGH was released initially from PLGA microspheres in its native form as measured by several assays. In isotonic buffer, pH 7.4 and 37°C, the rates of rhGH oxidation, diketopiperazine formation, and deamidation in the PLGA microspheres were equivalent to the rhGH in solution, but aggregation (dimer formation) occured at a slightly faster rate for protein released from the PLGA microspheres. This difference in aggregation rate was likely due to the high protein concentration used in the encapsulation process. The rhGH released was biologically active throughout the incubation at these conditions which are equivalent to physiological ionic strength and pH. Conclusions. rhGH was successfully encapsulated and released in its fully bioactive form from PLGA microspheres over 30 days. The chemical degradation rates of rhGH were not affected by the PLGA microspheres, indicating that the internal environment of the microspheres was similar to the bulk solution. After administration, the microspheres should become fully hydrated in the subcutaneous space and should experience similar isotonic conditions and pH. Therefore, if a protein formulation provides stability in isotonic buffer, pH 7.4 and 37°C, it should allow for a safe and efficacious sustained release dosage form in PLGA microspheres.     

Pharmacodynamics and pharmacokinetics of oral salmon calcitonin in the treatment of osteoporosis

Introduction: Salmon calcitonin (sCT) has been used for the treatment of postmenopausal osteoporosis for over 30 years. It is available in injectable and intranasal formulations. Two oral formulations have recently been developed.

Areas covered: The basis for oral sCT’s bioavailability rests with a carrier molecule (8-(N-2-hydroxy-5-chloro-benzoyl)-amino-caprylic acid) or an acid-resistant enteric coating (Eudragit® polymer containing citric acid). With these formulations, sCT is resistant to gastric acid, and thus becomes available for absorption at the higher pH of the small intestine. Even though the changes in bone mineral density and bone turnover markers are greater with oral compared to nasal sCT, it shows only minor effects on these surrogate markers.

Expert opinion: Oral sCT is attractive in concept as it is would be more convenient to patients than other routes of administration. While there may be other advantages to the oral formulation such as improving bone mineral density to a greater extent than nasal CT, anti-fracture efficacy has not been shown in a recent major clinical trial. Together with the possibility of an association between the drug and cancer and the availability of antiresorptive drug classes that are clearly more efficacious than sCT, successful development of oral sCT as a treatment for postmenopausal osteoporosis is uncertain.     

Development of a Polymeric Surgical Paste Formulation for Taxol

Purpose. To develop and characterize a biodegradable polymeric sustained release surgical paste formulation for taxol. Methods. Taxol was incorporated into poly(-caprolactone) (PCL) or blends of PCL with methoxypolyethylene glycol, MW 350 (MePEG). The surgical pastes were characterized using gel permeation chromatography, thermal analysis, scanning electron microscopy, and a tensile strength tester. In vitro release data for taxol from the surgical paste formulations was carried out at 37°C in phosphate buffered saline, pH 7.4, using an HPLC assay for taxol. Antiangiogenic activity of the formulations were assessed using a chick chorioallantoic membrane assay (CAM). Results. The addition of up to 30% MePEG in PCL decreased the melting point of PCL by 5°C and the tensile strength by 152.7 N/cm² to 26.7 N/cm² but increased the degree of PCL crystallinity from 42% to 51%. Taxol showed a biphasic in vitro release profile composed of a burst phase lasting 1 or 2 days followed by a period of slow sustained drug release. There was no significant difference in the release profiles of taxol from two different sources of PCL. The addition of MePEG increased the amount of water taken up by the polymer blends but decreased the rate of taxol release. The formulations were shown to have antiangiogenic activity by the CAM assay at levels as low as 0.1% taxol using 3 mg surgical paste pellets. Conclusions. Our surgical paste formulations for taxol give sustained release while having physical properties which can be adjusted using additives.     

Development of a Freeze-Dried Albumin-Free Formulation of Recombinant Factor VIII SQ

Purpose. To develop a stable freeze-dried formulation of recombinant factor VIII-SQ (r-VIII SQ) without the addition of albumin. Methods. Different formulations were evaluated for their protective effect during sterile filtration, freeze-thawing, freeze-drying, reconstitution and long term storage. Factor VIII activity (VIII:C), visual inspection, clarity, solubility, moisture content and soluble aggregates and/or fragments were assayed. Results. A combination of non-crystallising excipients (L-histidine and sucrose), a non-ionic surfactant (polysorbate 80) and a crystalline bulking agent (sodium chloride) was found to preserve the factor VIII activity during formulation, freeze-drying and storage. Calcium chloride was included to prevent dissociation of the heavy and light chains of r-VIII SQ. Sodium chloride was chosen as the primary bulking agent since the concentration of sodium chloride necessary for dissolution of r-VIII SQ in the buffer will inhibit the crystallization of many potential cake formers. It was found that L-histidine, besides functioning as a buffer, also protected r-VIII SQ during freeze-drying and storage. A pH close to 7 was found to be optimal. Some potential macromolecular stabilisers, PEG 4000, Haes^®-steril and Haemaccel^®, were evaluated but they did not improve the recovery of VII:C. The freeze-dried formulation was stable for at least two years at 7°C and for at least one year at 25°C. The reconstituted solution was stable for at least 100 hours at 25°C. Conclusions. The albumin-free formulation resulted in consistently high recovery of VII:C, very low aggregate formation and good storage stability. The stability of the reconstituted solution makes the formulation suitable for continuous administration via infusion pump. The formulation strategy described here may also be useful for other proteins which require a high ionic strength.     

Acyclovir Permeation Enhancement Across Intestinal and Nasal Mucosae by Bile Salt-Acylcarnitine Mixed Micelles

The purpose of this study was to investigate the absorption enhancement of acyclovir, an antiviral agent, by means of bile salt-acylcarnitine mixed micelles. The specificity, site dependence, palmitoyl-DL-carnitine chloride (PCC) concentration dependence, and effects of absorption promoters on acyclovir absorption via the nasal cavity (N) and four different intestinal segments of the rat, i.e., duodenum (D), upper jejunum (UJ), combined lower jejunum and ileum (LJ), and colon (C) were evaluated. The present study employed the rat in situ nasal and intestinal perfusion techniques and utilized sodium glycocholate (NaGC), three acylcarnitines, and their mixed micelles as potential nasal and intestinal absorption promoters. Acylcarnitines used were DL-octanoylcarnitine chloride (OCC), palmitoyl-DL-carnitine chloride (PCC), and DL-stearoylcarnitine chloride (SCC). All acylcarnitines and NaGC by themselves produced negligible enhancement of acyclovir absorption in the rat intestine, while OCC and SCC were totally ineffective in the nasal cavity. However, the mixed micellar solutions of NaGC with PCC or SCC could significantly increase the mucosal membrane permeability of acyclovir in the colon and nasal cavity. On the other hand, NaGC-OCC mixed micelles slightly increased the absorption of acyclovir by both routes. When a mixed micellar solution of NaGC with PCC was used, the rank order of apparent acyclovir permeability (P_app; cm/sec), corrected for surface area of absorption, was N (10.54 ± 0.62 x 10^–5) > D (6.82 ± 0.30 x 10^–5) > LJ (2.90 ± 0.08 x 10^–5) > C (2.54 ± 0.14 x 10^–5) > UJ (2.30 ± 0.22 x 10^–5). In contrast, the P_app rank order for acyclovir without any absorption promoter was D (2.49 ± 0.44 x 10^–5) > UJ (0.64 ± 0.03 x 10^–5) > LJ, C, and N (0). The effect of mixed micellar solutions was synergistic and was much greater than that with single adjuvants probably because of micellar solubilization of acylcarnitines by NaGC. The magnitude of absorption promotion was dependent on the hydrophobicity, i.e., carbon-chain length of the acylcarnitines. The enhanced permeability could be reversed within 60-120 min after removal of the adjuvant from the duodenum, colon, and nasal cavity. These results suggest that bile salt-acylcarnitine mixed micelles can be used as intestinal or nasal mucosal absorption promoters of poorly permeable agents.     

Intestinal Absorption of Octreotide Using Trimethyl Chitosan Chloride: Studies in Pigs

Purpose. To investigate the enhancing effect of trimethyl chitosan chloride (TMC) on the enteral absorption of octreotide and to delineate the required doses of both TMC and peptide in vivo in juvenile pigs. Methods. Six female pigs (body weight, 25 kg) were operated to induce a stoma at the beginning of their jejunum and to insert an in-dwelling fistula for intrajejunal (IJ) administration of the formulations. A silicone cannula was inserted at the jugular vein for blood sampling. One week after surgery the pigs received IJ octreotide solution administrations with or without TMC at pH 7.4 or chitosan HCl at pH 5.5. For determining bioavailability (F) values, the pigs also received an octreotide solution intravenously (IV). Blood samples were taken from the cannulated jugular vein and subsequently analyzed by radioimmunoassay. Results. Intrajejunal administration of 10 mg octreotide without any polymer (control solution) resulted in F values of 1.7 ± 1.1% (mean ± SE). Chitosan HCl 1.5% (w/v) at pH 5.5 led to a 3-fold increase in F compared to the control (non-polymer containing) formulations. Co-administration of octreotide with 5 and 10% (w/v) TMC at pH 7.4 resulted in 7.7- and 14.5-fold increase of octreotide absorption, respectively (F of 13.9 ± 1.3% and 24.8 ± 1.8%). IJ administration of 5 mg octreotide solutions resulted in low F values of 0.5 ± 0.6%, whereas co-administration with 5% (w/v) TMC increased the intestinal octreotide bioavailability to 8.2 ± 1.5%. Conclusions. Cationic polymers of the chitosan type are able to enhance the intestinal absorption of the peptide drug octreotide in pigs. In this respect, TMC at neutral pH values of 7.4 appears to be more potent than chitosan HCl at a weak acidic pH of 5.5.