Processing factors in development of solid solution formulation of itraconazole for enhancement of drug dissolution and bioavailability.

This study investigated solid solutions of itraconazole, a water insoluble antifungal, for improved dissolution and improved bioavailability. Influence of processing factors on drug and carrier properties in solid solution and subsequently on drug dissolution behavior was also studied. An optimized solid solution formulation was compared with marketed product in healthy human subjects under fasted and fed conditions for bioequivalency. Polyethylene glycol (PEG) and drug were made into a solid solution at 120 degrees C. The cooled, solid solution was then ground into granules of different sizes. Solid solutions of lower drug concentration dissolved at a faster rate, and drug dissolution improved considerably with increasing molecular weight of PEG. Initial treatment of itraconazole with the wetting agent/cosolvent glycerol prior to making itraconazole into a solid solution improved drug dissolution, and also reduced the PEG amount required to dissolve drug to form solid solution. Addition of a polymer such as HPMC to the solid solution eliminated precipitation of drug following dissolution. As the granule size of the solid solution was reduced, precipitation of drug during dissolution became prominent. Equivalence of two formulations could not be shown for pharmacokinetic parameters C(max) and AUC, under both fasting and fed conditions.

Preliminary bioequivalence testing of two nicardipine HCl sustained-release formulations with in vitro/in vivo correlations.

A new nicardipine HCl oral sustained-release dosage form was evaluated for bioequivalence in comparison with a reference product, Cardene SR. Six healthy subjects, fasted overnight, were enrolled in a single-dose, open-label, randomized, and two-way crossover study. Blood samples were collected over a 12 hour period, and nicardipine plasma concentrations analyzed from plasma. Pharmacokinetic parameters, including Cmax, t(max), and AUC, were obtained from drug plasma concentration-time curves and pharmacokinetic analysis conducted using WinNonlin. The two one-sided t-test was applied in statistical analysis for comparison of the pharmacokinetic parameters between the two products. There was no convincing evidence that nicardipine HCl test product and Cardene SR were bioequivalent. Amounts of nicardipine HCl release in vivo was mathematically obtained by deconvoluting plasma concentration-time data after oral administration using IV bolus injection data as a reference. Plots of percentages of drug release in vitro against those in vivo illustrated triphasic curves. After the in vitro time scale was corrected and then plotted against in vivo data, plots provided a polynomial relationship (R2 of 0.9920 and 0.9954). The in vitro/in vivo correlation may be useful in reformulating this particular test formulation to obtain a product with an in vivo release rate identical to Cardene SR.

Drug release from spray layered and coated drug-containing beads: effects of pH and comparison of different dissolution methods.

Based on dissolution profiles of three model drugs on spray layered beads with the same percentage of Aquacoat coating, it was concluded that in vitro dissolution of oral controlled-release formulations should be performed in both gastric and intestinal media for ionizable drugs. Ketoprofen (weak acid, pKa 4.8), nicardipine HCl (salt of weak organic base, pKa 8.6), and acetaminophen (very weak organic acid, pKa 9.7, not ionized at physiologic pH) provided different dissolution characteristics in enzyme-free simulated gastric fluid (pH 1.4) and enzyme-free simulated intestinal fluid (pH 7.4), indicating that the rate of drug release was pH dependent and related to drug ionization even though the solubility of the coating (ethylcellulose) is pH independent. In acidic media, ketoprofen release from the beads containing low-level coating (3%) was slower than that of nicardipine HCl, with the opposite holding true in basic media. Acetaminophen was released at approximately the same rate in both acidic and basic media. A comparison of drug release profiles for nicardipine HCl nude beads was also investigated among three different dissolution methods: USP dissolution apparatus I (basket method, 50 rpm), USP dissolution apparatus II (paddle method, 50 rpm), and USP dissolution apparatus III (Bio-Dis, Van-Kel Industries, 5 and 10 dpm). Release profiles obtained from all methods were similar, indicating that the three dissolution methods were comparable.

Bead compacts. II. Evaluation of rapidly disintegrating nonsegregating compressed bead formulations.

In this study, three techniques for the prevention or mitigation of polymer coat fracture on compaction of sustained-release beads into tablets were investigated. All techniques in this paper were evaluated without the addition of any cushioning excipients, but rather by spray coating these excipients to avoid segregation during product manufacturing. First, it was shown that use of swellable polymers such as polyethylene oxide (PEO) serves a unique and effective role in preventing polymer coat rupture. PEO was spray coated between the ethylcellulose (EC) and microcrystalline cellulose (MCC) coats to evaluate its cushioning effect. The compacted PEO layered beads, on dissolution, disintegrated into individual beads with sustained drug release of up to 8 hr. It is postulated that the PEO was hydrated and formed a gel that acts as a sealant for the cracks formed in the ruptured polymer coating (sealant-effect compacts). Second, EC-coated drug-layered beads were also overcoated with cushioning excipients such as polyethylene glycol (PEG) and MCC with an additional coating of a disintegrant. These beads were compressed at pressures of 125, 500, and 1000 pounds into caplets and, on dissolution testing, disintegrated into individual beads when the dissolution medium was switched from simulated gastric to intestinal fluid. The dissolution profiles show that the polymer coat was partly disrupted on compaction, leading to a total drug release in 8-10 hr. Third, EC-coated beads were also granulated with cushioning excipient and compressed.

Behavioural mode of action of deet: inhibition of lactic acid attraction.

Using the mosquito Aedes aegypti in a novel olfactometer that measures movement towards and away from a stimulus, we could not confirm that 'deet' is a repellent of mosquitoes. In the absence of a host, deet was an attractant and in the presence of a host, it was an inhibitor of attraction. This inhibition occurred in the gaseous phase and was therefore not the result of the physical properties of deet. We determined that L-lactic acid, a component of human sweat that is an attractant to mosquitoes, is the target of this inhibition, implying that lactic acid may be a bottleneck in the behavioural cascade preceding blood-sucking.

Multiple-layer compression-coated tablets: formulation and humidity studies of novel chewable amoxicillin/clavulanate tablet formulations.

The purpose of this study was to produce novel multiple-layer, compression-coated, chewable tablet formulations containing amoxicillin trihydrate, and clavulanic acid as potassium clavulanate, and to test in vitro dissolution characteristics and the effect of humidity stability compared to Augmentin chewable tablets as a reference. Double- and triple-layer tablets were manufactured on a laboratory scale by multiple-layer dry compression, and dissolution profiles of both active ingredients were determined. Tablets were subjected to stability evaluation in laboratory-scale humidity tanks maintained at constant humidity. Assay of content was determined by HPLC or UV spectroscopy. Physical characteristics of the powder mixture, such as angle of repose, and of tablets for hardness and friability, were also determined. Chewable tablets showed similar dissolution profiles in vitro for both active ingredients, compared to the marketed reference, Augmentin. The stability of clavulanic acid, but not amoxicillin, was increased in the novel triple or bilayer formulation. The tablets showed suitable friability, hardness, and angle of repose for starting materials to suggest that industrial scale-up is feasible. This approach to formulation of drugs containing multiple or moisture-sensitive ingredients has been shown to increase the stability of the central core drug without changing the dissolution pattern of the active ingredients. This formulation is expected to be bioequivalent in vivo based on these in vitro results.

Bead compacts. I. Effect of compression on maintenance of polymer coat integrity in multilayered bead formulations.

Little information is available on the compactability of beads for oral sustained-release dosage forms. It is known that polymer-coated beads may fuse together to produce a non-disintegrating controlled-release matrix tablet when compressed. This study evaluates the effect of compression on beads with multiple layers of polymer and drug coat, and the effect of cushioning excipients and compaction pressure on drug release from compressed bead formulations. The multilayered beads consist of several alternating layers of acetaminophen (APAP) and polymer coats (Aquacoat) with an outer layer of mannitol as a cushioning excipient. Percent drug release versus time profiles showed that the release of drug decreases from noncompacted beads as the amount and number of coatings increases, with only 43% of drug released in 24 hr for coated beads with 10 layers. It was shown that the compacted multilayered beads will disintegrate in gastrointestinal fluids, providing a useful drug release pattern. It was shown that beads of drug prepared by any method can be spray-layered with excipients such as Avicel and mannitol. Spray-layering of the cushioning excipient onto beads can provide an effective way to circumvent segregation issues associated with mixing of the polymer-coated beads and powdered or spherical/nonspherical cushioning excipients. Spray layering of the cushioning excipient can also provide excellent flow properties of the final formulation as visually observed in our experiments. Triple-layered caplets (TLC) were also prepared with outer layers of Avicel PH-101 or polyethylene oxide (PEO), and a center layer of polymer-coated beads. For TLC, the polymer coating on the beads fractured, and nondisintegrating matrix formulations were obtained with both caplet formulations.

Percutaneous absorption and model membrane variations of melatonin in aqueous-based propylene glycol and 2-hydroxypropyl-beta-cyclodextrin vehicles.

Percutaneous absorption and model membrane variations of melatonin (MT) in aqueous-based propylene glycol and 2-hydroxypropyl-beta-cyclodextrin vehicles were investigated. The excised hairless mouse skin (HMS) and two synthetic ethylene vinyl acetate (EVA) and microporous polyethylene (MPE) were selected as a model membrane. The solubility of MT was determined by phase equilibrium study. The vertical Franz type cell was used for diffusion study. The concentration of MT was determined using reverse phase HPLC system. The MT solubility was the highest in a mixture of PG and 2-HP beta CD. The percutaneous absorption of MT through excised HMS increased as the solubility increased. However, the permeability coefficient decreased and then slightly increased in a mixture of PG and 2-HP beta CD. On the other hand, both flux and permeability coefficient through EVA membrane decreased as the solubility increased. No MT was detected over 12 h after starting diffusion through MPE membrane. The flux of MT was dependent on the type of membrane selected. Flux of MT was greatest in excised HMS followed by EVA and MPE membrane. Flux of MT through EVA membrane was 5-20 times lower when compared to excised HMS. Interestingly, volumes of donor phase when MPE membrane was used, significantly increased during the study period. The HMS might be applicable to expect plasma concentration of MT in human subjects based on flux and pharmacokinetic parameters as studied previously. The current studies may be applied to deliver MT transdermally using aqueous-based vehicles and to fabricate MT dosage forms.

Transmucosal, oral controlled-release, and transdermal drug administration in human subjects: a crossover study with melatonin.

The effect of oral controlled-release (CR), oral transmucosal (buccal; TMD) and transdermal (TDD) drug delivery systems on plasma concentrations of melatonin (MT) and its principal metabolite in human subjects using a crossover, single dose design was evaluated. Twelve adult male volunteers participated in the study and received all three dosage forms on three separate occasions. All patch dosage forms were removed after 10 h of wear. Plasma concentrations of the parent drug and its metabolite, 6-sulfatoxymelatonin (MT6s) were measured by radioimmunoassay. Between-subject plasma concentrations of MT were very variable following both oral CR and TDD. Use of the oral CR system gave plasma MT profiles in some subjects that were initially similar to physiological levels, but then differed substantially from physiological in the rate of MT offset; in a few subjects, plasma MT levels remained consistently much below normal nocturnal physiological levels. Also, the ratio of metabolite to parent drug by the oral CR route was many times greater than physiological. TDD resulted in a significant delay in systemic drug levels and a gradual decline in drug delivery after patch removal, possibly due to deposition of melatonin in the skin. TDD failed to simulate the physiological plasma profile of MT (rapid achievement of steady-state blood levels and rapid decline after removal of the patch; i.e., so-called "square-wave" profile). TMD provided prompt systemic drug levels with less variability than oral CR or TDD delivery. Also, plasma MT levels fell promptly and rapidly after removal of the patch. No indication of mucosal deposition was observed. TMD was able to mimic the physiological plasma profiles of both MT and its principal metabolite.

Batch variation and pharmacokinetics of oral sustained release melatonin-loaded sugar spheres in human subjects.

The three different batches of an oral sustained release melatonin (MT) delivery system were prepared by aqueous-based fluid-bed coating of the sugar spheres for the evaluation ofin vitro release characteristics and plasma concentration profiles in human subjects. The MT contents in 20% coated sugar spheres of three batches (B1, B2 and B3) were 3.3+/-0.08, 2.4+/-0.1 and 2.5+/-0.13 mg per gram of coated sugar spheres, respectively. The release profiles of three different batches had a very similar fashion. However, the release half-lives (T(50%)) of MT from B1, B2 and B3 was 3.70+/-0.2, 5.2+/-0.2 and 4.9+/-0.07h, respectively. Plasma concentration profiles of sustained release 0.2mg melatonin-loaded sugar spheres containing 10% immediate release melatonin in gelatin capsules (B1 and B2) were then evaluated in human subjects. Thein vivo plasma concentration profiles of the two batches (B1 and B2) were very similar each other and located between the physiological endogenous ranges. The time to reach the peak concentration (T(max)) was more advanced in case of B1 when compared to B2. However, there was no statistically significant difference in the maximum concentration (C(max)) and the area under the curve (AUC) between B1 and B2. The AUC of melatonin-loaded sugar spheres containing 10% and 20% immediate release MT in human subjects had a good linearity between dose and AUC, regardless of the fraction of immediate release MT, indicating the first order elimination process of MT within these doses. The current oral sustained release MT delivery system may be utilized to treat circadian rhythm disorders if it is proven to be more clinically useful when compared to immediate release MT.

Solubility and stability of melatonin in propylene glycol and 2-hydroxypropyl-beta-cyclodextrin vehicles.

The physicochemical properties of melatonin (MT) in propylene glycol (PG) and 2-hydroxypropyl-beta-cyclodextrin (2-HPbetaCD) vehicles were characterized. MT was endothermally decomposed as determined by differential scanning calorimetry (DSC). Melting point and heat of fusion obtained were 116.9+/-0.24 degrees C and 7249+/-217 cal/mol, respectively. MT as received from a manufacture was very pure, at least 99.9%. The solubility of MT in PG solution increased slowly until reaching 40% PG and then steeply increased. Solubility of MT increased linearly as concentration of 2-HPbetaCD without PG increased (R(2)=0.993). MT solubility in the mixtures of PG and 2-HPbetaCD also increased linearly but was less than the sum of its solubility in 2-HPbetaCD and PG individually. The MT solubility was low in water, simulated gastric or intestinal fluid but the highest in the mixture of PG (40 v/v%) and 2-HPbetaCD (30 w/v%) although efficiency of MT solubilization in 2-HPbetaCD decreased as the concentration of PG increased. MT was degraded in a fashion of the first order kinetics (r(2)>0.90). MT was unstable in strong acidic solution (HCl-NaCl buffer, pH 1.4) but relatively stable in other pH values of 4 approximately 10 at 70 degrees C. In HCl-NaCl buffer, MT in 10% PG was more quickly degraded and then slowed down at a higher concentration. However, the degradation rate constant of MT in 2-HPbetaCD was not changed significantly when compared to the water. The current studies can be applied to the dosage formulations for the purpose of enhancing percutaneous absorption or bioavailability of MT.

Evaluation of commercial insect repellents on human skin against Aedes aegypti (Diptera: Culicidae).

An olfactometer was used to evaluate the efficacy of selected commercial insect repellent products against Aedes aegypti (L.). A comparison of 12 commercial repellent products was made on human skin. The products tested included 2 natural oil insect repellent formulations (Buzz Away and Green Ban) containing plant extracts, 2 proprietary products (Skin-So-Soft lotion and bath oil), and 8 commercial deet preparations in various concentrations and forms of spray, aerosol, stick, cream, and lotion. Behavioral responses and time to probe were determined in triplicate using 10 female mosquito challenges per replicate for each product. Generally, products with higher concentrations of deet were found to have longer repellence times. OFF spray and Muskol lotion offered the longest repellence times. However, there was no significant difference in time for mosquitoes to probe among the formulations. Skin-So-Soft lotion and bath oil were not as effective as deet in repelling Ae. aegypti. Natural oil insect repellent formulations offered essentially no repellency against Ae. aegypti. This is a simple and reproducible method to evaluate the efficacy of insect repellents and is recommended for preliminary screening of new insect repellents or formulations.

Biomodulation of the toxic and nutritional effects of small bowel bacterial overgrowth in end-stage kidney disease using freeze-dried Lactobacillus acidophilus.

Small bowel bacterial overgrowth (SBBO), well known to occur in end-stage kidney failure, is responsible for producing uremic toxins and contributing to the patient's decreased nutritional well-being. In this study, 8 hemodialysis patients were treated with a course of oral Lactobacillus acidophilus (LBA) in an attempt to alter this SBBO. LBA treatment was effective in lowering 2 compounds generated in vivo. Serum dimethylamine (DMA) levels dropped from 224 +/- 47 to 154 +/- 47 micrograms/dl at the end of LBA treatment (p < 0.001). Nitrosodimethylamine, a carcinogen, levels also decreased significantly from 178 +/- 67 (untreated) to 83 +/- 49 ng/kg (after LBA treatment). Patients nutritional status, assessed as serum albumin, body weight, caloric intake, midarm muscle area (MAMA) and appetite improved modestly, but not significantly. LBA changed small bowel pathobiology by modifying metabolic actions of SBBO, reducing in vivo generation of toxins and carcinogens and promoting nutrition with no adverse side effects.

Preliminary evaluation of transdermal delivery of melatonin in human subjects.

A transdermal delivery device (TDD)1 was applied to four human subjects to investigate whether melatonin (MT) could penetrate through human skin. The TDD (total surface area of 3.80 cm2) was applied to the forearm of each subject. Plasma MT concentrations increased above baseline in approximately 2-4 hours, although steady state was not achieved in the 8-hour study period. Intersubject variation of plasma MT among four subjects was noted. Urinary excretion of 6-sulphatoxymelatonin (6-STMT), a major metabolite of MT in humans, increased as plasma MT concentrations increased. Cumulative amounts of urinary 6-STMT increased over a 6-hour period when the TDD was applied and were three times greater than in controls. The urinary excretion rate of 6-STMT was statistically correlated with plasma MT concentration among subjects (r2 = 0.77). These data suggest that the urinary excretion rate of 6-STMT can be used as an index of MT plasma concentrations in human subjects. Although an intersubject variability in both plasma MT concentration and urinary excretion rate of 6-STMT was noted, it was evident that MT can be delivered transdermally in human subjects.

Calcium alginate beads as core carriers of 5-aminosalicylic acid.

The utilization of calcium alginate beads as core carriers for delayed dissolution followed by burst release as a potential method of intestinal site specific drug delivery was investigated. 5-Aminosalicylic acid was spray-coated on dried calcium alginate beads and then coated with different percentages of enteric coating polymer and/or sustained-release polymer. Beads coated with more than 6% (w/w) methacrylic copolymer plastisized with dibutyl sebacate and triethyl citrate resisted release in 2-hr acid fluid challenge and allowed immediate dissolution upon transfer to simulated intestinal fluid. With 6% (w/w) methacrylic copolymer on top of 4% (w/w) ethylcellulose polymer, the major portion of drug did not release in 2 hr of acid treatment or the next 3 hr of simulated intestinal fluid treatment. This dosage form provides the possibility to deliver drug to the lower intestinal tract with minimal early release, followed by sustained release in the colon.

Pharmacokinetics and pharmacodynamics in the design of controlled-release beads with acetaminophen as model drug.

Relationships between pharmacodynamics (drug concentration and effect) and pharmacokinetics were used to develop an oral, controlled-release-bead dosage form. Reported pharmacodynamic data were used with pharmacokinetic curves to identify effective therapeutic drug concentrations for optimum therapy for a drug with a "deep tissue" effective compartment. The commonly used, over-the-counter, non-narcotic, analgesic-antipyretic acetaminophen (APAP) was used as the model drug. Data reported in the literature were used to compare analgesic and antipyretic efficacy. Computer simulations were performed with MAXSIM (version 3.01) to suggest a zero-order drug release useful for a 12-h, oral, sustained-dosage form for antipyretic therapy in children, on the basis of current pediatric dosing of APAP. Coated APAP beads with the desired release rate were then developed with fluid-bed coating technology.

Multiple-dose acetaminophen pharmacokinetics.

Four different treatments of acetaminophen (Tylenol) were administered in multiple doses to eight healthy volunteers. Each treatment (325, 650, 825, and 1000 mg) was administered five times at 6-h intervals. Saliva acetaminophen concentration versus time profiles were determined. Noncompartmental pharmacokinetic parameters were calculated and compared to determine whether acetaminophen exhibited linear or dose-dependent pharmacokinetics. For doses less than or equal to 18 mg/kg, area under the curve (AUC), half-life (t1/2), mean residence time (MRT), and ratio of AUC to dose for the first dose were compared with the last dose. No statistically significant differences were observed in dose-corrected AUC for the first or last dose among subjects or treatments. Half-lives and MRT were not significantly different among treatments for the first or the last dose. Statistically significant differences in t1/2 and MRT were noted (p less than 0.05) among subjects for the last dose. A plot of AUC versus dose for the first and the last doses exhibited a linear relationship. Dose-corrected saliva concentration versus time curves for the treatments were superimposable. Thus, acetaminophen exhibits linear pharmacokinetics for doses of 18 mg/kg or less. Plots of AUC versus dose for one subject who received doses higher than 18 mg/kg were curved, suggesting nonlinear behavior of acetaminophen in this subject.

Antimicrobial activity of Microgard against food spoilage and pathogenic microorganisms.

Microgard, a commercially available fermented milk product containing antimicrobial metabolites, was a potent inhibitor for Gram-negative bacteria such as Pseudomonas, Salmonella, and Yersinia when 1% concentration was incorporated into agar media. Gram-positive Bacillus cereus, Staphylococcus aureus, and Listeria monocytogenes were insensitive to Microgard. Kluyveromyces marxianus, an unidentified black yeast, and Penicillium expansum were partially suppressed, whereas Aspergillus niger and a yogurt spoilage yeast were tolerant to 5% Microgard. Optimum activity of Microgard was at pH 5.3 and below; the concentration that gave complete inhibition depended upon the number of bacteria present as well as the genus tested. Blood agar base reversed the antagonistic activity of Microgard against Pseudomonas putida compared with plate count agar.

Gastrointestinal transit of nondisintegrating, nonerodible oral dosage forms in pigs.

Gastrointestinal (GI) transit data necessary as "baseline" or "control" information were collected using pigs as animal models preliminary to bioavailability studies of new sustained action formulations. Density and size effects of nondisintegrating dosage forms on GI transit were investigated. Initially, enteric-coated nondisintegrating magnesium hydroxide caplets (density, 1.5 g/ml; size, 19.6 x 9.5 mm; weight, 1.2 g) were utilized in seven pigs. Prolonged gastric residence (greater than 5 days) occurred in every case for this dosage form. Therefore, nondisintegrating caplets of three densities (1.25, 1.45, and 2.3 g/ml) and three different sizes (large, 20 x 10 mm; medium, 10 x 10 mm; small, 5 x 10 mm) were studied in two more pigs. Roentgenography was used to visualize passage of caplets through the GI tract. Heidelberg pH capsules (size, 8 x 20 mm; density, 1.61 g/ml) were also used in this study. Total GI transit times range from 2 to 33 days for 22 administrations of these nondisintegrating dosage forms. Pigs are found to not be an appropriate model for evaluating bioavailability of nondisintegrating controlled-release dosage forms because total GI transit time (especially gastric transit) is much too long.

Lactobacillus effects on cholesterol: in vitro and in vivo results.

A double blind investigation was conducted on the influence of a commercially available tablet containing Lactobacillus acidophilus and Lactobacillus bulgaricus (Lactinex Becton Dickinson Microbiology Systems, Cockeysville, MD) on human serum lipoprotein concentrations. Tablets containing about 2 X 10(6) viable bacteria of Lactobacillus mixtures or placebo tablets were ingested by 354 nonfasting informed subjects in a dose of one tablet each, taken four times a day. There was a 3-wk washout period between two 6-wk treatment periods. The number of viable lactobacillus in unused returned tablets was the same at the end of the study as in the beginning. Analysis of paired data using Wilcoxon signed ranks test showed no major effects on lipoprotein concentrations for either the placebo-treated group or the lactobacilli-treated group. There were no statistically significant differences for low density lipoprotein concentrations between the lactobacilli-treated group and the placebo-treated group. The high density lipoprotein concentrations increased 1.8 to 3.0 mg/dl in both groups for both study periods. For total cholesterol the placebo-treated group experienced a statistically significant increase in the first period according to the Wilcoxon signed ranks test (from 208.0 to 215.0 mg/dl, P less than .001) but not according to a two-sample Student t test. Total cholesterol did not change significantly for the Lactobacillus-treated group in either period. Cardiac risk factor (ratio of total cholesterol to high density cholesterol) did not vary during the study. Lipoprotein values increased immediately following vigorous exercise compared with following 15 min of resting without either placebo or treatment. Sample controls for assay and reassay gave virtually identical values (coefficient of variation 1.6%), confirming that assay results were quite reliable. Thus, ingestion of commercially available Lactobacillus tablets, which contain about 2 X 10(6) cfu/tablet of L. acidophilus and L. bulgaricus cells in a dose of four tablets daily did not affect serum lipoprotein concentrations.