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PubMed2002

2,6-Dichloroquinone chlorimide and 7,7,8,8-tetracyanoquinodimethane reagents for the spectrophotometric determination of salbutamol in pure and dosage forms.

A simple, rapid and sensitive spectrophotometric method for the determination of sulbutamol in pure form and in different pharmaceutical preparations has been developed. The charge transfer (CT) reaction between salbutamol as electron donor and 2,6-dichloroquinone chlorimide (DCQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as a pi-electron acceptor have been spectrophotometrically studied. The optimum experimental conditions for these CT reactions have been studied carefully. Beer's law is obeyed over the concentration range of 1.0-30.0 microg ml(-1) and 2.0-20.0 microg ml(-1) for salbutamol using DCQ and TCNQ, respectively. For more accurate results, Ringbom optimum concentration range is calculated and found to be 10.0 to 30.0 and 8.0 to 20 microg ml(-1) for salbutamol using DCQ and TCNQ, respectively. The Sandell sensitivity is found to be 0.011 and 0.010 g cm(-2) for salbutamol using DCQ and TCNQ, respectively, which indicate the high sensitivity of the proposed methods. Relative standard deviations (R.S.D.) of 0.27 to 0.68% and 0.20 to 1.40% (n=5) were obtained for five replicates of salbutamol using DCQ and TCNQ, respectively. The results obtained by the two reagents are comparable with those obtained by British pharmacopoeia assay for the determination of salbutamol in raw materials and in pharmaceutical preparations.

Adrenergic beta-Agonists↗
PubMed2005

The effects of substrate size, surface area, and density on coat thickness of multi-particulate dosage forms.

Drugs layering experiments were performed in a fluid bed fitted with a rotor granulator insert using diltiazem as a model drug. The drug was applied in various quantities to sugar spheres of different mesh sizes to give a series of drug-layered sugar spheres (cores) of different potency, size, and weight per particle. The drug presence lowered the bulk density of the cores in proportion to the quantity of added drug. Polymer coating of each core lot was performed in a fluid bed fitted with a Wurster insert. A series of polymer-coated cores (pellets) was removed from each coating experiment. The mean diameter of each core and each pellet sample was determined by image analysis. The rate of change of diameter on polymer addition was determined for each starting size of core and compared to calculated values. The core diameter was displaced from the line of best fit through the pellet diameter data. Cores of different potency with the same size distribution were made by layering increasing quantities of drug onto sugar spheres of decreasing mesh size. Equal quantities of polymer were applied to the same-sized core lots and coat thickness was measured. Weight/weight calculations predict equal coat thickness under these conditions, but measurable differences were found. Simple corrections to core charge weight in the Wurster insert were successfully used to manufacture pellets having the same coat thickness. The sensitivity of the image analysis technique in measuring particle size distributions (PSDs) was demonstrated by measuring a displacement in PSD after addition of 0.5% w/w talc to a pellet sample.

Chemistry, Pharmaceutical↗
PubMed1991

Sensitivity analysis of the effect of bioavailability or dosage form content on mean steady state phenytoin concentration.

Stochastic simulations were used to examine the sensitivity of mean phenytoin steady state concentrations (Css) to changes in the effective dosing rate produced by differences in average product content or bioavailability. Changes of +/- 4%, +/- 6%, +/- 8% and +/- 10% in the effective dosing rate (based on a starting dose yielding a Css of 15 mg/L) were examined. Monte Carlo simulations were performed for each change in dosing rate assuming a one-compartment open model with parallel Michaelis-Menten and first-order elimination. Parameter sets were comprised of a combination of values for maximal rate of saturable elimination (410 or 510 mg/day), the concentration at which the rate of saturable elimination is half maximum (Km, 4.4 or 5.7 mg/L), and linear clearance (CL, 0.15 or 1.5 L/day). These parameters were assumed to be log-normally distributed with coefficients of variation of 30%, 50%, and 15%. The percentages of "individuals" who would be predicted to have Css of less than 10 mg/L following a reduction in the effective dosing rate increased with decreasing Km and CL values. For a Km of 5.7 mg/L and CL of 1.5 L/day, 5% of the "individuals" had Css values of less than 10 mg/L with an 8% decrease in the dosing rate. If the dosing rate was reduced by 10%, then 14-16% of the "individuals" were predicted to have concentrations of less than 10 mg/L. All other combinations of Km and CL values yielded higher percentages of "individuals" with Css of less than 10 mg/L.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Availability↗
PubMed2004

Development of clinical dosage forms for a poorly water soluble drug I: Application of polyethylene glycol-polysorbate 80 solid dispersion carrier system.

Different formulation approaches were evaluated to ensure that the formulation of a poorly water soluble compound chosen during early development achieves optimum bioavailability. The insoluble compound has an aqueous solubility of 0.17 micro g/mL at 25 +/- 1 degrees C, a relatively high permeability (Caco2 P(app) = 6.1 x 10(-4) cm/min), and poor bioavailability in dogs (dry blend formulation). Based on the prediction by GastroPlus, the oral absorption of this compound is sensitive to its apparent solubility and particle size. The oral bioavailability of three different formulations was compared in a dog model: a cosolvent-surfactant solution, a solid dispersion in a mixture of polyethylene glycol 3350 and polysorbate 80, and a dry blend of micronized drug with microcrystalline cellulose. In absence of a parenteral injection, the bioavailability of the solution was considered to be 100%, and the relative oral bioavailability of the three formulations was 100, 99.1, 9.8, respectively. Comparable bioavailability was obtained with the solid dispersion and the cosolvent-surfactant solution, both of which showed a 10-fold higher bioavailability than the dry blend. Thus, a 20 mg dose strength capsule containing the solid dispersion formulation was selected for clinical development. The selected solid dispersion system was physically and chemically stable for at least 16 months at 25 degrees C/60% RH. In conclusion, the bioavailability of a poorly water soluble drug was greatly enhanced using the solid dispersion formulation containing a water soluble polymer with a surface active agent.

Animals↗
PubMedDate not supplied

Spectrophotometric determination of acyclovir and ribavirin in their dosage forms.

Two simple, accurate, and reliable spectrophotometric methods have been developed for the determination of 2 antiviral drugs, acyclovir (ACV) and ribavirin (RBV), in their pharmaceutical formulations. These methods are based on oxidation of the 2 drugs with either cerium (IV) ammonium sulfate (Method A) or potassium persulfate (Method B). The products of oxidation in both methods are coupled with 3-methylbenzothiazolin 2-one hydrazone, producing a deep blue color with a maximum absorption wavelength at 630 nm. In Method A, the absorbance-concentration plots were linear over the ranges of 5-50 and 10-60 microg/mL with detection limits of 0.18 microg/mL (8 x 10(-7) M) and 0.63 microg/mL (2.58 x 10(-6) M) for ACV and RBV, respectively. In Method B, the ranges were 5-45 and 20-50 microg/mL with detection limits of 0.11 microg/mL (4.88 x 10(-7) M) and 1.40 microg/mL (5.73 x 10(-6) M) for the 2 drugs, respectively. The molar absorptivities were 4.1 x 10(3) and 3.65 x 10(3) L/mol/cm in Method A and 5.03 x 10(3) and 3.97 x 10(3) L/mol/cm in Method B for the 2 drugs, respectively. The proposed methods were applied successfully for the determination of the 2 drugs in their pharmaceutical formulations. The percentage recoveries +/- standard deviation were 99.57 +/- 0.86 and 100.82 +/- 0.46 for ACV; 99.41 +/- 1.08 and 100.35 +/- 1.03 for RBV. The results obtained were compared statistically with those given by official methods and showed no significant differences regarding accuracy and precision.

Acyclovir↗
PubMed2003

Fluorimetric determination of some antibiotics in raw material and dosage forms through ternary complex formation with terbium (Tb(3+)).

A highly sensitive and specific fluorimetric method was developed for the determination of cefazolin sodium I, cefoperazone sodium II, ceftriaxone sodium III, and cefixime IV. The proposed method involves the formation of ternary complex with Tb(3+) in the presence of Tris buffer. The quenching of the terbium fluorescence due to the complex formation was quantitative for the four studied drugs. The effect of pH, concentration of Tris buffer and terbium were studied. The formation of the complex was highly dependent on the pH. The optimum pH was found to be pH 8 for cefazolin sodium I, ceftriaxone sodium III, cefixime IV and pH 10 for cefoperazone sodium II. The optimum concentration for Tb(3+) was found 1 ml of 10(-4) M solution and for Tris buffer 1 ml of the prepared solution. Under the described conditions, the proposed method was applicable over the concentration range 8.79 x 10(-6)-7.91 x 10(-5), 9.7 x 10(-6)-4.49 x 10(-)5, 6.10 x 10(-6)-2.50 x 10(-5), and 4.92 x 10(-6)-2.95 x 10(-5) mol with mean percentage accuracy of 99.79+/-0.24, 98.97+/-1.25, 100.05+/-0.79, and 100.15+/-0.54 for I, II, III, and IV, respectively. The proposed method was applied successfully for the determination of studied drugs in bulk powder and in pharmaceutical formulations. The results obtained by applying the described method were statistically analyzed and compared with those obtained by applying the official method. The proposed method was used as stability indicating method for the determination of the studied drugs in the presence of their degradation products.

Anti-Bacterial Agents↗
PubMed2006

Spectrophotometric determination of flucloxacillin and dicloxacillin in pure and dosage forms.

A simple, rapid and accurate spectrophotometric method for the determination of antibiotic drugs, flucloxacillin (Fluclox) and dicloxacillin (Diclox), in pure form and different pharmaceutical preparations has been developed. The charge transfer (CT) reactions between Fluclox and Diclox as electron donors and 7,7,8,8-tetracyanoquinodimethane (TCNQ) and tetracyanoethylene (TCNE) as pi-acceptors to give highly coloured complex species have been spectrophotometrically studied. The optimum experimental conditions for these CT reactions have been studied carefully. Beer's law is obeyed over the concentration ranges of 4-180 microg mL(-1) and 4-70 microg mL(-1) for Fluclox and Diclox drugs using TCNQ and TCNE reagents, respectively. The Sandell sensitivities (S) are found to be 0.016-0.035 microg cm(-2) and 0.011-0.016 microg cm(-2) for Fluclox and Diclox, respectively, which indicate the high sensitivity of the proposed method. The relative standard deviations (R.S.D.: 0.08-0.49 and 0.15-0.80) for the determination of Fluclox and (R.S.D.: 0.05-0.75 and 0.13-0.75) for Diclox were obtained for four to six replicates using TCNQ and TCNE reagents, respectively, refer to the high accuracy and precision of the proposed method. These results are also confirmed by the between-day precision and the percent recovery of 99.90-100.1 and 99.60-100.4 for Fluclox and 99.90-100.5 and 99.40-100.1 for Diclox using TNCQ and TCNE reagents, respectively. The results obtained for the two reagents are comparable with those obtained by the official method.

Anti-Bacterial Agents↗
PubMedDate not supplied

Simultaneous determination of losartan and hydrochlorothiazide in combined dosage forms by first-derivative spectroscopy and high-performance thin-layer chromatography.

Losartan (LST) is the first orally active nonpeptide angiotensin-II receptor antagonist with an improved safety and tolerability profile. It is prescribed alone or in combination with hydrochlorothiazide (HCTZ) for the treatment of moderate-to-severe hypertension. This paper describes the development of 2 methods that use different techniques, first-derivative spectroscopy and high-performance thin-layer chromatography (HPTLC), to determine LST and HCTZ in the presence of each other. LST and HCTZ in combined preparations were quantitated by using the first-derivative responses at 271.6 nm for LST and 335.0 nm for HCTZ in spectra of their solutions in water. The linearity ranges are 30-70 microg/mL for LST and 7.5-17.5 microg/mL for HCTZ with correlation coefficients of 0.9998 and 0.9997, respectively. In the HPTLC method, a mobile phase of chloroform-methanol-acetone-formic acid (7.5 + 1.5 + 0.5 + 0.03, v/v) and a prewashed Silica Gel G60 F254 TLC plate as the stationary phase were used to resolve LST and HCTZ in a mixture. Two well-separated and sharp peaks for LST and HCTZ were obtained at Rf values of 0.61+/-0.02 and 0.41+/-0.02, respectively. LST and HCTZ were quantitated at 254.0 nm. The linearity ranges obtained for the HPTLC method are 400-1200 and 100-300 ng/spot with corresponding correlation coefficients of 0.9944 and 0.9979, for LST and HCTZ, respectively. Both methods were validated, and the results were compared statistically. They were found to be accurate, specific, and reproducible. The methods were successfully applied to the estimation of LST and HCTZ in combined tablet formulations.

Angiotensin Receptor Antagonists↗
PubMed2004

Preformulation studies to meet the challenges in the manufacture of betaine solid dosage form.

The objectives were (1). to perform solid-state characterization of anhydrous betaine (A) and betaine monohydrate (M), (2). to develop a pressure differential scanning calorimetric (DSC) technique for the quantification of M when present as a minor component in a mixture with A and, (3). to study the effect of annealing of A on the kinetics of A --> M transition. X-ray powder diffractometer (XRD), DSC, thermogravimetric analyzer (TGA), and an automated moisture sorption apparatus were used to characterize the phases. DSC at an elevated pressure of 200 psi enabled quantification of M in mixtures of A and M. Humidity-controlled TGA allowed study of the kinetics of A --> M transition. Automated moisture studies showed that A has a strong tendency to sorb water (at RH >or= 20%, 25 degrees C) and convert to M. When M was subjected to DSC at ambient pressure, the endotherms due to dehydration and vaporization of water overlapped. Pressure DSC enabled separation of these two thermal events. In mixtures of A and M, the enthalpy of dehydration (deltaH(d)) of M could be used for its quantification. A linear relationship was obtained when deltaH(d) was plotted as a function of the weight fraction of M in the mixture. The limits of detection and quantification of M in A were 0.15% and 1.5% w/w, respectively. The kinetics of water uptake by the annealed as well as the unannealed A, could be best described by the Avrami-Erofeev model (three-dimensional nucleation and growth). The calculated rate constant (k) of unannealed A (0.075 +/- 0.002 min(-1)) was significantly higher than that of annealed A (0.052 +/- 0.004 min(-1)). DSC at elevated pressure was a sensitive technique for quantification of M when present as a mixture with A. Annealing of A decelerated the A --> M phase transition reaction, possibly by increasing the degree of crystallinity of A.

Betaine↗
PubMed2005

Spectrophotometric study of the reaction mechanism between DDQ Pi- and iodine sigma-acceptors and chloroquine and pyrimethamine drugs and their determination in pure and in dosage forms.

Two simple and accurate spectrophotometric methods are presented for the determination of anti-malarial drugs, chloroquine phosphate (CQP) and pyrimethamine (PYM), in pure and in different pharmaceutical preparations. The charge transphere (CT) reactions between CQP and PYM as electron donors and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) pi-acceptor and iodine sigma-acceptor reagents to give highly coloured complex species have been spectrophotometrically studied. The optimum experimental conditions have been studied carefully. Beer' law is obeyed over the concentration range of 1.0-15 microg ml(-1) for CQP and 1.0-40 microg ml(-1) for PYM using I(2) and at 5.0-53 microg ml(-1) for CQP and 1.0-46 microg ml(-1) for PYM using DDQ reagents, respectively. For more accurate results, Ringbom optimum concentration range is calculated and found to be 10-53 and 8-46 microg ml(-1) for CQP and PYM using DDQ, respectively and 5-15 and 8-40 microg ml(-1) for CQP and PYM using iodine, respectively. The Sandell sensitivity is found to be 0.038 and 0.046 g cm(-2) for DDQ method and 0.0078 and 0.056 g cm(-2) for I(2) method for CQP and PYM, respectively which indicates the high sensitivity of both methods. Standard deviation (S.D.=0.012-0.014 and 0.013-0.015) and relative standard deviation (R.S.D.=0.09-1.4 and 1.3-1.5%) (n=5) for DDQ and I(2) methods respectively, refer to the high accuracy and precision of the proposed methods. These results are also confirmed by between day precision of percent recovery of 99-100.6%, and 98-101% for CQP and PYM by DDQ method and 99-102% and 99.2-101.4% for CQP and PYM by I(2) method respectively. These data are comparable to those obtained by British and American pharmacopoeias assay for the determination of CQP and PYM in raw materials and in pharmaceutical preparations.

Antimalarials↗
PubMed2006

Spectrophotometric study of the reaction mechanism between DDQ as pi-acceptor and potassium iodate and flucloxacillin and dicloxacillin drugs and their determination in pure and in dosage forms.

Two simple and accurate spectrophotometric methods are presented for the determination of beta-lactam drugs, flucloxacillin (Fluclox) and dicloxacillin (Diclox), in pure and in different pharmaceutical preparations. The charge transfer (CT) reactions between Fluclox and Diclox as electron donors and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) pi-acceptor and potassium iodate via oxidation reduction reaction where the highly coloured complex species or the liberated iodine have been spectrophotometrically studied. The optimum experimental conditions have been studied carefully. Beer's law is obeyed over the concentration range of 2-450 microg ml(-1) for Fluclox and 10-450 microg ml(-1) for Diclox using DDQ reagent and at 50-550 microg ml(-1) for Fluclox and 50-560 microg ml(-1) for Diclox using iodate method, respectively. For more accurate results, Ringbom optimum concentration range is calculated and found to be 6-450 and 15-450 microg ml(-1) for Fluclox and Diclox using DDQ, respectively, and 65-550 and 63-560 microg ml(-1) for Fluclox and Diclox using iodine, respectively. The Sandell sensitivity is found to be 0.018 and 0.011 microg cm(-2) for DDQ method and 0.013 and 0.011 microg cm(-2) for iodate method for Fluclox and Diclox, respectively, which indicates the high sensitivity of both methods. Standard deviation (S.D.=0.01-0.80 and 0.07-0.98) and relative standard deviation (R.S.D.=0.13-0.44 and 0.11-0.82%) (n=5) for DDQ and iodate methods, respectively, refer to the high accuracy and precision of the proposed methods. These results are also confirmed by between-day precision of percent recovery of 99.87-100.2 and 99.90-100% for Fluclox and Diclox by DDQ method and 99.88-100.1 and 99.30-100.2% for Fluclox and Diclox by iodate method, respectively. These data are comparable to those obtained by British and American pharmacopoeias assay for the determination of Fluclox and Diclox in raw materials and in pharmaceutical preparations.

Benzoquinones↗
PubMedDate not supplied

Controlled release from an electrorheological fluid dosage form: experimental results for a prototype system.

A new controlled-release technology that is based on electrorheological fluids (ERF) is described, and a model system is investigated. Humidified starch (duration of humidification is 30-35 minutes) was used as a filler material (approximately 20% w/w) in olive oil to make the ER system, and benzocaine (BZN) was used as the model drug. The average particle size of starch in the olive oil was approximately 200 nm. 1N HCl was used as the receiver medium and BZN was assayed by UV spectroscopy at 226 nm. A series of studies was done at five temperatures (25 degrees, 30 degrees, 35 degrees, 40 degrees, and 45 degrees C) and two external electric fields (E-fields) that were generated by applying potential drops across the diffusion apparatus of 0 V and 290 V. Control studies of BZN release from olive oil without filler showed little or no increase in release rates resulting from application of E-fields. In addition, while reversing the polarity for BZN in olive oil caused differences in release rates, these differences were too small to explain the results obtained for the ER systems. It was found that release of BZN increased significantly with the application of the electric field (approximately 53% increase at 25 degrees C). A plot of the log of the release rate vs 1/T was linear for the 0 V data but deviated from linearity for the 290 V data. The increase in release rates due to the E-field became smaller as the temperature was increased. The results are consistent with (but are not sufficient to prove) the hypothesis that the increased release rate is due to a small amount of ordering of the cornstarch filler particles in response to the applied E-field, which results in a reduction in the tortuosity of the system.

Anesthetics, Local↗
PubMed1999

Assay for the determination of low dosage form of formoterol dry syrup by capillary electrophoresis with head-column field-amplified sample stacking.

The development of a capillary zone electrophoresis method with head-column field-amplified sample stacking injection for the determination of formoterol (FMTR) in a low dosage dry syrup form was described. To obtain the highest sensitivity, the sample solution was prepared by high content of organic solvent with the presence of a small amount of H+ (60-100 microM) and the capillary inlet end was dipped in water before electroinjection. This method was fully validated in terms of repeatability (RSDs for migration time, peak area of FMTR and peak area ratio between FMTR and I.S. at 1 microg/ml of FMTR was 0.76, 1.10 and 0.55% respectively), reproducibility (RSDs from different capillaries, analytes, days and instruments were 1.52%, 1.04%, 1.16% and 1.93% respectively), linearity (y = 0.827x - 0.085, r = 0.9993 (n = 6) over the range of 0.25-2.0 microg/ml), limits of quantitation, ruggedness and robustness. The method was applied to the determination of the drug in commercial dry syrup preparation (recovery was 100.9%, RSD = 1.5%, n = 5) and proved to be fast and reliable for the quantitation analysis of FMTR in the pharmaceutical form.

Bronchodilator Agents↗
PubMed2003

Drug nano- and microparticles processed into solid dosage forms: physical properties.

The use of nanoparticles of relatively insoluble drugs has enormously widened the window of achievable pharmacokinetic performance. For the successful development of this technology, it is essential to understand the characteristics of nanoparticles. In this study, the processability and solid dosage performance of nanoparticulates are compared with those of microparticulates. Nanoparticle suspensions are first prepared by wet comminution in the presence of stabilizers. Spray drying converts them into dried particles from which compacts are prepared. Nanoparticles easily form aggregates during spray drying. These aggregates can be slowly redispersed into nanoparticles in water. Compacts show differences in their internal structure and micromechanical deformations, according to the size of their primary particles. Stress to break and indentation hardness are found to be only slightly higher in nanoparticulate systems.

Administration, Oral↗
PubMed1978

Oral administration of erythromycin stearate: effect of dosage form on plasma levels.

The clinical effectiveness of three different oral dose forms of erythromycin stearate was assessed by following plasma levels during continued dosage. The assessment was carried out in 12 volunteers who took 250 mg of the drug every six hours in a cross-over design with intravenous administration of erythromycin lactobionate as a reference. While in some patients levels which were obtained after the initial dose were low, plasma levels sufficient to inhibit the majority of bacterial pathogens which cause acute respiratory tract infections were obtained and maintained after the second dose.

Adult↗
PubMed1988

Spectrophotometric assays of diloxanide furoate and tinidazole in combined dosage forms.

Two spectrophotometric methods have been developed for the simultaneous determination of diloxanide furoate and tinidazole in combined dosage formulations without prior separation. The first method is based on the measurement of the absorbance of a methanolic solution of the sample at 259 and 311 nm and application of a simplified Vierordt equation for the determination of diloxanide furoate, whereas tinidazole is determined by direct spectrophotometry. The second method is a difference spectrophotometric procedure based on measurement of the absorbance of the sample solution in water relative to that of an acidic or alkaline solution of identical concentration at the appropriate wavelength of maximum difference absorption. The results are calculated by reference to standard absorptivity values.

Journal Article↗
PubMed2003

Furosemide pharmacokinetics and pharmacodynamics following gastroretentive dosage form administration to healthy volunteers.

The objective of this study was to evaluate the pharmacokinetic and pharmacodynamic properties of furosemide following gastroretentive dosage from (GRDF) administration. A furosemide (60 mg) GRDF, releasing the drug during 6 hours in vitro, or an immediate-release tablet was administered to healthy male volunteers (N = 14) in a crossover design. Food and liquid intake were standardized; urine was collected, weighed, and assayed for furosemide and sodium concentrations. Pharmacokinetics of furosemide following the GRDF administration, as compared to the tablet, showed lower Cmax and indicated a prolonged absorption phase leading to longer mean residence time in the stomach. The sustained input of the drug significantly improved diuretic and natriuretic efficiencies during the first 5 hours and thereby increased the total effects measured over 24 hours. The unfolding controlled-release GRDF of furosemide improved the pharmacodynamic actions due to the sustained absorption in the stomach and jejunum, which delayed the body's counteractivity to the drug effect.

Adult↗
PubMed1976

Serum ampicillin levels in the calf: influence of dosage, route of administration and dosage form.

Holstein bull calves received ampicillin sodium by the intravenous, intramuscular and subcutaneous routes and ampicillin trihydrate by the intramuscular route, at a dosage of 5 mg/kg. In addition ampicillin sodium and ampicillin trihydrate were given at a 12 mg/kg dosage intramuscularly. The serum ampicillin concentrations were determined at five, 30, 60, 120, 180, 240 and 300 min after drug administration and at 360 min after ampicillin trihydrate injection. Intravenous administration gave a high initial level (16.2 mug/ml) at five min that declined to below 1 mug/ml by 120 min. Subcutaneous administration produced the lowest initial levels of drug but concentrations of drug detected did not differ significantly from the intramuscular administration at any sampling interval. The 12 mg/kg intramuscular ampicillin sodium dosage produced significantly higher levels than the 5 mg/kg dosage only at five min. Ampicillin trihydrate gave higher levels than ampicillin sodium at all times except 30 min (5 mg/kg) and five min (12 mg/kg). The serum ampicillin disappearance study (5 mg/kg intravenous) gave a two component bi-exponential curve. Kinetic analysis of the first component showed a C01 (theoretical initial conc) of 44.8 mug/ml, a ke1 (rate constant of disappearance) of 0.064 mug min and a t1/21 (calculated half-life) of 10.8 min. The Co2, ke2 and t1/22 of the second component were 6.2 mug/ml, 0.0157 mug/min and 46.2 min respectively.

Ampicillin↗