Glass vials for small volume parenterals: influence of drug and manufacturing processes on glass delamination.

PURPOSE: Studies were initiated to examine the effect of formulation and process variables on the delamination process and also the influence of the glass manufacturing process, supplier, and glass surface treatment. METHODS: Stress testing was performed by exposing filled vials to multiple sterilization cycles followed by accelerated stability testing. Delamination incidence was determined by visual examination, light obscuration (HIAC), and microscopical methods. The inner surface of vials from each supplier and lot were also examined by scanning electron microscopy. RESULTS: Vials sourced from Supplier A had smooth surfaces as demonstrated by SEM examination, whereas vials sourced from Suppliers B and C displayed extensive surface imperfections such as pitting and/or deposits. These imperfections were localized to the vial wall, adjacent to the vial bottom, and increased with sulfate treatment. Delamination incidence increased in those vial lots with increased surface imperfections. Thus, vials sourced from Supplier A had the lowest frequency of delamination. Sulfate treatment and high pH increased delamination incidence to as high as 100%. CONCLUSION: These results demonstrate the importance of the surface morphology created during the vial forming process. Given the diferences observed, final vial selection should include extensive microscopical and product stress testing studies on multiple vial lots.

Enhanced chemical stability of the intracellular prodrug, 1-[((S)-2-hydroxy-2-oxo-1,4,2-dioxaphosphorinan-5-yl)methyl]cytosine, relative to its parent compound, cidofovir.

Degradation kinetics of cyclic HPMPC (cHPMPC), 1-[((S)-2-hydroxy-2-oxo-1,4,2-dioxaphosphorinan-5-yl)methyl]cytosi ne, and its parent compound cidofovir (also known as HPMPC) were conducted in the pH range of 2-11 at 70 degrees C. cHPMPC manifested greater chemical stability than cidofovir, except under alkaline conditions (pH?9). Three degradation products-cidofovir, cyclic HPMPU and HPMPU-were identified for cHPMPC, and the product distribution was characterized via a stability-indicating HPLC assay. Cyclic HPMPU and HPMPU are the uracil analogs of cHPMPC and cidofovir, respectively, formed through a hydrolytic deamination pathway. The deamination and hydrolysis rate constants for cHPMPC under acidic conditions were derived from the degradation product curves. The deamination rate constants for cHPMPC were about 8-fold slower compared to that for cidofovir. The enhanced chemical stability for cHPMPC relative to cidofovir is attributed to the absence of intramolecular catalysis with cHPMPC.

Characterization of metal-ion-nucleotide based particulate matter in solutions of 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA).

The antiviral drug 9-[2-(phosphonomethoxy)ethyl]adenine, PMEA, was developed as an intravenous product for the treatment of human immunodeficiency virus infection. During the course of stability monitoring, PMEA i.v. injection was found to undergo particulate matter formation under extended storage at ambient temperature. Isolation and characterization of the particulates revealed them to be metal ion-PMEA complexes. The principle metal ions associated with the particulates were iron and zinc, present as trace impurities (< or = 40 ppm) in PMEA drug substance determined by inductively coupled argon plasma spectroscopy. These visible particles are characterized by energy-dispersive x-ray spectrometry and fourier transform infrared spectroscopy. This study describes the systematic evaluation of the observed solution phenomena and details alternative formulation systems to eliminate particulate formation in the PMEA injectable product.

Oral formulations of adefovir dipivoxil: in vitro dissolution and in vivo bioavailability in dogs.

The effect of formulation on oral bioavailability of the antiviral nucleotide analogue adefovir from the prodrug adefovir dipivoxil was examined in beagle dogs. A suspension formulation of adefovir dipivoxil granules was administered to five fasted male beagle dogs (250 mg prodrug per dog; 135.7 mg-equiv of adefovir per dog). Tablets prepared from the same granulation (batch B94) were administered at 2 x 125 mg prodrug per dog. In addition, the same tablets were administered to dogs in the fed state or following pentagastrin pretreatment. Two further tablet batches (H94 and D501) with slight formulation changes were also evaluated in pentagastrin pretreated dogs (n = 5). Concentrations of adefovir in plasma were determined by HPLC following fluorescence derivatization. Tablet dissolution was examined at pH 2.0. One batch of adefovir dipivoxil tablets showed a 5-fold slower dissolution rate in vitro (B94 = H94 >> D501). Adefovir dipivoxil was completely converted to adefovir following oral absorption in dogs. The oral bioavailability of adefovir from the suspension was 35.0 +/- 8.9%. The oral bioavailability of adefovir from the tablet formulation was 34.7 +/- 10.3%, 37.2 +/- 4.5%, and 44.9 +/- 5.9% in fasted dogs, fed dogs and fasted dogs pretreated with pentagastrin, respectively. All three tablet batches had equivalent bioavailability in dogs. Oral bioavailability of adefovir from the prodrug in dogs (35-46%) was unaffected by formulation, food, or the acidic pH of the gastrointestinal tract. In vitro dissolution of adefovir dipivoxil tablets did not correlate with oral bioavailability. Oral bioavailability of adefovir dipivoxil appears to be limited by low permeability and biological conversion of the prodrug to adefovir.

Stability of cidofovir in 0.9% sodium chloride injection and in 5% dextrose injection.

The stability of cidofovir in i.v. admixtures under refrigerator and room temperature conditions was studied. Admixtures of cidofovir 0.21 and 8.12 mg/mL in 0.9% sodium chloride injection or 5% dextrose injection and of 0.085 and 3.51 mg/mL in 5% dextrose and 0.45% sodium chloride injection were prepared in triplicate in polyvinyl chloride (PVC) or polyethylene-polypropylene containers and i.v. administration sets and stored for 24 hours at 2-8 or 30 degrees C. The lower concentration of cidofovir corresponded to an assumed dose of 0.5 mg/kg for a 40-kg patient, and the higher concentration to an assumed dose of 10 mg/kg for a 100-kg patient. Samples were removed at 0 and 24 hours and analyzed for cidofovir concentration by high-performance liquid chromatography. Physical compatibility was also studied. The stability of cidofovir in 0.9% sodium chloride injection and in 5% dextrose injection at low- and high-dose concentrations was unaffected by storage at either temperature. All admixtures were clear, colorless, and free of visible particles or precipitation. There were no substantial changes in pH or number of particles of > or = 10 microns in diameter. Cidofovir 0.21 and 0.12 mg/mL was stable in 0.9% sodium chloride injection and 5% dextrose injection in PVC and polyethylene-polypropylene containers and i.v. administration sets for up to 24 hours at 2-8 and 30 degrees C. Cidofovir was compatible with the injectable solutions studied.

Optimization of in vitro flux through hairless mouse skin of cidofovir, a potent nucleotide analog.

The in vitro flux (4-8 h) of cidofovir (1-[(S)-3-hydroxy-2-(phosphonomethoxy)propyl]cytosine) was measured across full-thickness hairless mouse skin to evaluate potential formulations for local treatment of herpes virus infections. The effects of propylene glycol, isopropyl alcohol, oleic acid, pH, and cidofovir concentration were examined. In addition, several prototype aqueous gel formulations were studied. Flux values (4-8 h) increased linearly with cidofovir concentration in both solution and gel formulations. Removal of the stratum comeum by tape stripping increased the flux by approximately 400-fold, whereas pH (4.5 versus 7) had little effect on flux. The presence of propylene glycol, isopropyl alcohol, or their combination did not significantly increase mean flux (p > or = 0.05). Pretreatment of the skin with oleic acid resulted in a significant enhancement of cidofovir flux (p < or = 0.01). From the measured flux values, the calculated concentration of cidofovir achievable in the viable epidemis from a 1% cidofovir gel formulation was approximately 14 micrograms/mL, which is comparable to the in vitro 50% inhibitory dose (ID50) values for herpes simplex viruses HSV-1 and HSV-2.

Oral bioavailability of the antiretroviral agent 9-(2-phosphonylmethoxyethyl)adenine (PMEA) from three formulations of the prodrug bis(pivaloyloxymethyl)-PMEA in fasted male cynomolgus monkeys.

The bioavailability of PMEA from three oral formulations of the prodrug bis(POM)-PMEA has been evaluated in fasted male cynomolgus monkeys. The formulations examined included a hydroxypropyl-beta-cyclodextrin (HPBCD) complex, a PEG based cosolvent solution, and an aqeous suspension. Oral formulations containing 3H-bis(POM)-PMEA were compared to intravenous 3H-PMEA at 10.9 mg-eq/kg in a crossover study in four monkeys, with a 7 day washout period. No intact bis(POM)-PMEA or monoester were detected in plasma. Bioavailabilities of PMEA from the prodrug were 24.7 +/- 6.5%, 27.3 +/- 12.3% and 22.2 +/- 15.6% for the HPBCD complex, PEG solution and aqueous suspension, respectively. The oral bioavailability of PMEA from bis(POM)-PMEA was not limited by dissolution rate of the prodrug. Data for the PEG cosolvent solution and suspension indicate that the prodrug could potentially be formulated as a soft gelatin capsule or a tablet.

Stability of interleukin 1 beta (IL-1 beta) in aqueous solution: analytical methods, kinetics, products, and solution formulation implications.

The thermal stability of IL-1 beta in aqueous solution as a function of temperature (5-60 degrees C), pH (2-9), buffer (acetate, citrate, tris, and phosphate), and cyroprotectants (sugars, HSA) was investigated in this study. The analytical methodologies included RP-HPLC, SEC, ELISA, IEF-PAGE, SDS-PAGE, and bioassay. The degradation and inactivation of IL-1 beta at or above 39 degrees C were attributed to autoxidation of the two cysteine residues in the denatured protein, followed by hydrophobic/covalent aggregation and precipitation. At or below 30 degrees C, IEF- and SDS-PAGE results suggest a possible deamidation reaction. The difference in mechanism of degradation precludes the prediction of formulation shelf life from accelerated temperature data. Nonetheless, the good stability observed at 5 degrees C suggests that a solution formulation may be feasible for IL-1 beta.

Quantitative evaluation of the stability and delivery of interleukin-1B by infusion.

The stability and delivery of IL-1 beta has been characterized in a polypropylene based syringe pump infusion system and in polyvinyl chloride based infusion bags, at concentrations ranging from 100 ng/mL to 1 microgram/mL. At higher concentrations (1 microgram/mL), minimal drug loss was observed in both systems. At low doses (100 ng/mL) in the syringe-pump system, the addition of 1% human serum albumin was necessary to prevent significant drug absorption to the polypropylene drug reservoir.

Development and characterization of a lyophilized dosage form of IL-1 beta.

The development and characterization of a lyophilized dosage form for recombinant Interleukin-1 beta is described. Included in the evaluation of the drug product are accelerated and long-term stability studies utilizing a number of biophysical techniques (reverse-phase HPLC, SDS-PAGE, isoelectric focusing and ELISA). Data collected with these methods were examined for correlations with biological activity assessments provided by an in-vitro cell culture system (mouse thymocyte proliferation). Results of these studies demonstrate that a lyophilized dosage form of Interleukin-1 beta can be prepared which retains its potency for at least 1 year when stored at ambient temperature. The analytical methodology used to assess the physicochemical integrity of the protein provided a sensitive and reproducible means of predicting changes in biological activity.

Preclinical development and characterization of an intravenous dosage form for the ACE inhibitor RS-10029.

Preclinical development of an intravenous dosage form for the ACE inhibitor RS-10029 involved the formulation and characterization of the drug's chemical/physical stability in two prototype formulations (injectable solution and lyophilized powder). Included in these studies were quantitative evaluations of various processing and administration parameters (membrane qualification, terminal sterilization, compatibility/delivery of the drug with typical infusion fluids and administration sets) on finished product integrity and quality. Analytical methodology used in these studies consisted primarily of a stability specific HPLC assay and a light obscuration based sensor (HIAC) for particulate matter analysis. Results of these studies indicate that the drug is relatively stable at ambient temperature and under accelerated storage conditions (predicted T90 at 25 degrees C greater than 2 yr, and T90 at 50 degrees C greater than 2 mo). However, the ability of the product to withstand a full terminal sterilization cycle is limited, and therefore other approaches toward sterile processing were examined. With regard to the stability and compatibility of the drug in a variety of fluids and devices there appears to be no overt limitations in its use for either bolus or infusion delivery.

An unexpected pH effect on the stability of moexipril lyophilized powder.

Because of the limited stability of moexipril (RS-10085; 1) in aqueous solution, lyophilized parenteral formulations were evaluated as a function of pH in this study. In general, the lyophilized powder of 1 showed about two orders of magnitude less reactivity at 50 degree C than in aqueous solution at pH values below 3 or above 6. At pH 5.1, however, the lyophilized powder had maximum reactivity, with the rate actually comparable to that observed in aqueous solution. When the distribution of the two major products, diketopiperazine (DKP) 2 and ester hydrolysis analogue 3, was compared to the observed kinetics as a function of pH, it was clear that removal of water via lyophilization suppressed the spontaneous k1 cyclization process, the spontaneous k3 hydrolysis process, and the specific base-catalyzed k4 hydrolysis process. The overall spontaneous k2 cyclization process, however, was not affected by lyophilization. The latter result is accounted for by the increased equilibrium constant for the formation of the tetrahedral intermediate, To, as a result of lyophilization. This study demonstrates that stability data in solution can not be used for predicting the stability of moexipril in lyophilized powder form.

Electrochemical evaluation of the interaction between ascorbic acid and the cardiotonic drug RS-82856.

The solution phase interaction between ascorbic acid and the cardiotonic drug N-cyclohexyl-N-methyl-4(7-oxy 1,2,3,5-tetrahydroimidazol[2,1-b] quinazolin-2-one butyramide (RS-82856) was evaluated using a differential pulse voltammetric technique. Shifts in the peak potential of ascorbic acid to higher energy as well as decreases in peak current values were monitored as a function of RS-82856 concentration. The electrochemical data were obtained under conditions where both the drug and the ascorbic acid concentrations exhibited linear relationships with peak current values. The methodology was extended to the study of two other structurally related phosphodiesterase inhibitors cilostamide and anagrelide. The complexation of these drugs with ascorbic acid were also characterized by decreases in the diffusion currents of ascorbic acid as well as by anodic shifts in the peak potential. The significance of these observations may be related to the inhibition of cyclic nucleotide phosphodiesterase activity by both the drugs tested and the ascorbic acid.

Stability of ganciclovir sodium (DHPG sodium) in 5% dextrose or 0.9% sodium chloride injections.

The stability of 9-[(1,3-dihydroxy-2-propoxymethyl]) guanine sodium (ganciclovir sodium, also known as DHPG sodium) in two infusion solutions was studied. Lyophilized ganciclovir sodium 500 mg was reconstituted with sterile water 10 mL to give a theoretical concentration of 50 mg/mL. After reconstitution, 6-mL aliquots of the solution were added to 100 mL of 0.9% sodium chloride injection or 5% dextrose injection in polyvinyl chloride i.v. bags. One sample was withdrawn from each of 10 bags of each solution and analyzed by high-performance liquid chromatography (HPLC). Thirty bags of each solution were then stored under each of the following conditions: at room temperature under laboratory light, at room temperature in the dark, and under refrigeration for up to five days. Single potency assays were performed by HPLC on each of three bags of solution at three and five days after initial dilution of the solutions. The solutions were visually inspected, and the pH of the solutions was measured. All solutions of ganciclovir were stable for at least five days under all storage conditions; mean ganciclovir concentrations did not drop below 98% of initial theoretical values throughout the storage period. No important changes in the pH of the solutions occurred during the study period. Under the conditions of this study, ganciclovir sodium is stable for up to five days when prepared in 5% dextrose injection or 0.9% sodium chloride injection.

Multidimensional column-switching liquid chromatographic method for dissolution testing of enprostil soft elastic gelatin capsules.

Enprostil (methyl 7-[(1 R,2R,3R)-3-hydroxy-2-[(E)-(3R)-3-hydroxy-4- phenoxy-1-butenyl]-5-oxocyclopentyl]-4,5-heptadienoate), an E-type prostaglandin exhibiting anti-ulcer activity, is formulated as a propylene carbonate solution filled into soft elastic gelatin (SEG) capsules. Enprostil SEG capsules were maintained for timed intervals at 50 degrees C, 30 degrees C, and room temperature, and the quantity of drug released upon complete capsule dissolution was determined as a function of storage condition. The dissolution test adhered to USP XXI guidelines (paddle method) and used a multidimensional HPLC technique to provide a sensitive and selective enprostil assay. Parallel HPLC assays determined the enprostil concentration in the propylene carbonate fill that was physically expressed from initially manufactured and from aged capsules. This corrected for any enprostil loss via chemical degradation on storage. The study included six different aged samples (six replicates each), and for all six samples, the enprostil recovered from dissolved capsules averaged 104 +/- 1.4% of the enprostil physically expressed from the capsules. Similarly, the enprostil recovered from dissolved, aged capsules averaged 103 +/- 5% of the enprostil physically expressed from capsules at the initial time point. These findings exclude the possibility that interactions with the SEG capsule wall reduce drug availability during storage under normal conditions. The multidimensional HPLC technique should generally extend to analysis of other noncationic drugs formulated into soft gelatin capsules.

Water soluble complexes of the antiviral drugs, 9-[(1,3-dihydroxy-2-propoxy)methyl]guanine and acyclovir: the role of hydrophobicity in complex formation.

We investigated water-soluble complexes of various ligands with the antiviral drugs, 9-[(2-hydroxyethoxy)methyl]guanine (acyclovir) and 9-[(1,3-dihydroxy-2-propoxy)methyl]guanine (DHPG). For comparison, we also examined the "parent" compounds, guanine and guanosine, as substrates for complex formation. Using the phase-solubility technique, we measured formation constant (K1) values at 23 degrees C in pH 7 buffer. For a single substrate, formation constants with different ligands varied in the order: caffeine greater than pyridoxine approximately cytidine greater than nicotinamide greater than sucrose. With caffeine as the ligand, formation constants with different substrates varied in the order: guanine greater than guanosine approximately acyclovir greater than DHPG. The largest formation constant observed was 58 M-1 (for guanine-caffeine), and the smallest formation constant was 0.29 M-1 (for DHPG-sucrose). Examining the literature for formation constant data on compounds related to DHPG, and comparing literature data with our own, reveals a significant correlation between formation constants and ligand hydrophobicity. For 41 substrate-ligand pairs, least squares linear regression analysis of log K1 values versus various parameters reflecting donor-acceptor abilities (e.g., substrate and ligand HOMO and LUMO values, or substrate oxidation potentials) failed to significantly correlate. We conclude that ligand hydrophobicity is a general determinant of water soluble complex formation, but not necessarily the exclusive or dominant controlling factor for all complexes. Charge-transfer interactions are not important determinants of complex formation for the substrate-ligand combinations that we have considered.

Intranasal delivery of nicardipine in the rat.

The intranasal absorption of nicardipine hydrochloride was characterized in an in vivo rat model system in which the normal mechanisms of mucociliary clearance and drainage of an instilled dose were not physically altered. The results obtained in this manner, therefore, are expected to be predicative of the delivery and absorption dynamics exhibited in the nasal mucosa of primates and humans. Intranasal delivery of nicardipine was studied in male rats using this model on single-dose administration of 1.0 mg/kg, and compared with both oral and intravenous administration. The effect of the addition of a viscosity agent, hydroxyethyl cellulose, on plasma levels following nasal delivery was also examined. Nicardipine plasma levels were determined by a rapid and specific reversed-phase HPLC method with electrochemical detection that employed nifedipine as an electroactive internal standard in the analysis. The limit of quantitation for nicardipine at 1.0 V versus Ag/AgCl was 8 ng/mL and the linear dynamic range was 15-150 ng/mL. Following intravenous administration the area under the plasma concentration curve was 5110 ng . min/mL as compared to 3730 ng . min/mL following intranasal dosing. This corresponds to a bioavailability of 73%. The addition of a viscosity agent to the nasal formulation was found to give a slight but statistically insignificant increase in the systemic availability (77%). Plasma levels of nicardipine following oral administration (1.0 mg/kg) were determined to be below the limit of quantitation of the analytical technique. These results therefore suggest that nasal delivery of nicardipine is a viable and efficient route of administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrochemistry of purine derivatives. 1: Direct determination for the antiviral drug 9-[(1,3-dihydroxy-2-propoxy)methyl]guanine by anodic differential pulse voltammetry.

Differential pulse voltammetry at a stationary glassy carbon electrode was used for the sensitive and selective analysis of a potent new antiviral analogue of 2-deoxyguanosine in a pharmaceutical formulation. In the electrochemical method for analysis of 9-[1,(3-dihydroxy-2-propoxy)methyl] guanine (1), an electroactive internal standard (uric acid) was used. Linear peak current-concentration relationships were obtained at 1 concentrations of 0.4-2.0 mM, with a quantitation limit of 0.1 mM. Degraded solutions of 1 were assayed directly by differential pulse voltammetry and also by two chromatographic methods to demonstrate the specificity of the electrochemical method. The voltammetric method reliably provides accurate and reproducible results in considerably less time than conventional chromatographic analysis.