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Excipient reactions have resulted from the use of clearly toxic substances (e.g. diethyleneglycol), the use of certain excipients in a susceptible group (e.g. very low birthweight neonates, patients with large surface area burns, patients with a history of asthma or contact dermatitis), the alteration of an excipient mixture resulting in altered bioavailability (e.g. phenytoin), and the deliberate or inadvertent extradural administration of preserved medications intended for intravenous use. Inadvertent excipient overdose has also occurred when unusually large doses of a drug containing a preservative were used [chlorbutol in morphine, ethanol in glyceryl trinitrate (nitroglycerin)]. Most excipient problems are preventable with knowledge of the currently available formulation. Government drug regulatory agencies have largely prevented introduction of a new toxic excipient; however, the new use of previously approved (but not adequately studied) excipients continues to result in unfortunate tragedies (e.g. the E-ferol incident). Populations at risk should be monitored carefully. Very low birthweight infants (less than 100g) have a well-demonstrated intolerance to many excipients, particularly during the first 2 weeks of life. Research should be directed toward development of non-preserved medications and safer diluents for this population. Drugs and excipients which have previously been demonstrated to be safer in other populations (e.g. doxapram) should be meticulously studied in this age group before widespread use is recommended. Asthmatic patients comprise another population that are frequently sensitive to excipient toxicity. In some cases, as in sulphiting agents, which are ubiquitous in foods as well as in medications, total avoidance may not be possible and prophylactic therapy may be beneficial. Inactive ingredients are clearly not consistently inert in their biological activity and therefore should not be listed as such. A more useful and concise term is excipient. It is highly recommended that all pharmaceutical manufacturers list all their excipients and make this available to practitioners and drug information centres. Alternatively or additionally, the package insert should list these excipients in accordance with good manufacturing procedures. This disclosure will help to determine the relative frequency and magnitude of problems (bioequivalence, toxicity, etc.) that excipients may have in the population, as well as enabling susceptible patients to avoid inadvertent exposure.
Theophylline ethylcellulose microcapsules were tableted by compression with or without excipients [lactose or hydroxypropyl cellulose (HPC-H)]. Tablets without excipients had a crushing strength that was independent of the applied compression force and the particle size of the microcapsules used, but tablet thickness decreased with an increase in the particle size of the microcapsules. The dissolution characteristics of theophylline from tableted microcapsules without excipients were almost independent of the applied compression force, but showed a sustained-release behavior. However, the thickness, crushing strength, and dissolution properties of tablets containing excipients were found to be affected by the type of excipient. Tableted microcapsules containing lactose showed an increase in tablet crushing strength that correlated with an increase in the applied compression pressure, but the tablet thickness did not change. In contrast, tableted microcapsules containing HPC-H showed a decrease in tablet thickness with an increase in the applied compression pressure, but the tablet crushing strength was initially reduced and then increased with an increase in the compression force. There was a rapid release rate for theophylline from tableted microcapsules containing lactose; a zero-order release rate for theophylline was found in tableted microcapsules containing HPC-H. The insoluble compacted matrix formation, disintegration of tablet, rupture of microcapsules, and gel matrix formation may be responsible for the release behavior of theophylline-tableted microcapsules with or without excipients. The reduced surface area and porosity resulted in a prolongation of the release from tableted microcapsules compared with untableted microcapsules.
Systemic administration of recombinant human interleukin-2 (rIL-2) is used for treating some patients with advanced cancer. This therapy is limited by severe adverse reactions of cardiovascular and gastrointestinal origin. The effects of rIL-2 treatment on plasma levels of some prostanoids were examined in sheep in order to elucidate the mechanism of these adverse reactions. A total of 8 adult female Suffolk sheep were used. rIL-2 (0.1 mg/kg) was infused over a 30-min period in 4 sheep. Four different sheep in the control group received an excipient, which consisted of 5% mannitol and sodium dodecyl sulfate (SDS) (187 micrograms SDS/mg rIL-2), in the same way. Plasma levels of prostaglandin (PG) F2 alpha in rIL-2-treated animals showed significant increases from 1.5 to 6 h over the excipient treated animals with a maximal increase of 138% of the pooled zero time control value (p less than or equal to 0.01) at 6 h. The pooled zero time control plasma PGF2 alpha concentration was 443.0 +/- 45.9 pg/ml. Plasma levels of 6-keto-PGF1 alpha in rIL-2-treated animals showed a significant increase (p less than or equal to 0.02) over the excipient treated animals at 0.5 h but the value was only 103% of the pooled zero time control. Plasma levels of 6-keto-PGF1 alpha in excipient-treated animals showed a maximal increase of 156% of the pooled zero time control value (55.6 +/- 8.9 pg/ml) at 5 h and it was significantly higher than the rIL-2-treated sheep.(ABSTRACT TRUNCATED AT 250 WORDS)
Dissolution rates and particle sizes of phenylbutazone solvent deposited on lactose, starch, and silicon dioxide, separately, and of norethindrone and digoxin deposited on lactose were investigated. Microparticulate dispersed drugs on the surface of excipients result when drug-to-excipient ratios are low. Fast dissolution rates are observed for such systems. This effect can be extended to higher ratios when silicon dioxide is used as the excipient. Because of adsorption, however, the release from silicon dioxide is more or less limited.
Micronized prednisone was used to study the effect of powder mixing on drug-excipient interactions and their effect on in vitro dissolution from uncompacted, hand-filled capsules. Two powder formulations contained CaHPO4 X 2H2O (dibasic calcium phosphate dihydrate) as a filler and potato starch or sodium starch glycolate as a disintegrant. The third powder formulation contained pregelatinized starch as a disintegrant/filler. The lubricant in these formulations was magnesium stearate. When drug, CaHPO4 X 2H2O, and the disintegrant were thoroughly mixed and hand filled into capsules without compaction, only approximately 70% of the drug dissolved in 30 min. The incomplete dissolution of the drug was caused by the formation of agglomerates and the inclusion of the drug particles by these agglomerates. In contrast, when a mixture of drug and pregelatinized starch was used, complete dissolution of the drug was achieved after 30 min due to the absence of agglomeration and inclusion. Prolonged mixing of the formulation containing CaHPO4 X 2H2O with magnesium stearate resulted in a decrease in the dissolution rate. The total amount of the drug dissolved at the end of 30 min was reduced from 70 to 20%. The decrease in the rate of drug dissolution resulted from drug-excipient interactions which caused flaking of the magnesium stearate particles. The adhesion of these flakes to the drug particles and drug-excipient agglomerates resulted in hydrophobic coating which reduced water penetration. The rate of drug dissolution was not affected when drug and pregelatinized starch were mixed with magnesium stearate for a prolonged time due to the absence of magnesium stearate flaking and film formation.
Two lubricants, magnesium stearate and sodium stearyl fumarate, were compared under identical mixing conditions to study their roles in drug-excipient interactions. After prolonged mixing, sodium stearyl fumarate did not interact with the drug or excipients; as a result, the disintegration time and drug dissolution rate from hand-filled, uncompacted capsules were not adversely affected. In contrast, magnesium stearate did exhibit drug-excipient interactions which resulted in lamination and subsequent adhesion of the lubricant to the drug-crospovidone agglomerates. These interactions adversely affected the disintegration time and drug dissolution rate from hand-filled, uncompacted capsules. Although the initial specific surface area of magnesium stearate was higher than that of sodium stearyl fumarate, flaking of magnesium stearate due to particulate-particulate interactions caused a large increase in the surface area. The adhesion of the magnesium stearate flakes to the drug-crospovidone agglomerates resulted in a decrease in the drug dissolution rate.
A method for the determination of the particle size of tablet excipients involving the use of video recording of microscopic examination of powders is described. The projected area of the particle profile was measured, and Feret's diameter and shape factors such as the elongation ratio, bulkiness factor, and surface factor were determined. Starch particles are the smallest among the excipients studied. Primojel particles are two to three times larger (Feret's diameter) and have up to 10 times greater projected areas. Particles of Avicel PH101, Ac-Di-Sol, Nymcel ZSD16 and ZSB10, and Polyplasdone XL have an irregular surface which results in large differences between the projected area diameter and the perimeter diameter. Particles of Nymcel and Ac-Di-Sol have the highest elongation ratio because of their cylindrical shape. Both Primojel and Starch have a low surface factor because of their spherical shape. This video-recording method is a simple system to observe, record, store, and retrieve particle-size data from microscopic examination of tablet excipients.
Biodegradable controlled-release microsphere systems made with the biocompatible biodegradable polyester excipient poly [DL lactide-co-glycolide] constitute an exciting new technology for drug delivery to the central nervous system (CNS). The present study describes functional observations indicating that implantation of dopamine (DA) microspheres encapsulated within two different polymer excipients into denervated-striatal tissue assures a prolonged release of the transmitter in vivo. Moreover, in this regard, the results show that there were clear cut temporal differences in the effect of the two DA microsphere formulations compared in this study, probably reflecting variations in the actual composition (i.e., lactide to glycolide ratio) of the two copolymer excipients examined. This technology has considerable potential for basic research with possible clinical application.
The bioavailability (plasma concentrations, AUC and urinary excretion) of an oral solution of rifampicin was investigated in six healthy volunteers. Simultaneous administration of PAS granules produced a significant decrease in the absorption of RMP, whereas Na-PAS tablets had no effect. This indicated that the dosage form of the granules and not PAS itself was responsible for the interaction, and that the dissolution of RMP was not involved. The interaction could be reproduced by giving dummy granules that contained the same excipients but no PAS. The disintegration and dissolution of PAS granules in vitro correlated well with the disappearance of RMP from the solution. The major excipient of the granules, bentonite (a mineral closely related to kaolin), was found to adsorb rifampicin rapidly and strongly.
Sustained-release implants for insulin can be made by compressing a powder admixture with palmitic acid as the excipient. At less than 20%, insulin does not disperse uniformly in the admixture. The size distribution of the excipient particles obtained after grinding for 15 min does not affect the sustained release action. When tested in a 33 d period, an 1/8-size piece (approximately 25 mg) implant cut from a pellet disc containing 20% insulin which is 13 mm in diameter and 1.5 mm thick released 0.12-0.17 mg insulin/d in diabetic Wistar rats. The 1/8-size piece containing 20% insulin or a rod of similar weight with a diameter of 3 mm, which can be inserted by a trocar, was optimal for the implant to provide a service-life of 49 +/- 7 d. The service-life decreased with progressive reduction in implant size. The implant functioned just as well subcutaneously or intraperitoneally and was eroded subcutaneously by 33.6-53.1% in 33 d. The glycosylated haemoglobin contents of diabetic animals on implant therapy which had a blood glucose level of 4.7 +/- 2.5 mmol/l were in a range of 6.2-8.9% compared to the control value of greater than 13% with chronic hyperglycemia. The overall results indicated that the implant was a promising alternative to daily insulin injections.
The drug-excipient incompatibility screen for moexipril hydrochloride (1) using various isothermal stress methods is reported herein. It was found that most of the commonly used filters, disintegrants, lubricants, glidants, and coating agents were incompatible with 1 in dry powder mixtures; moisture and basic (or alkalizing) agents were determined to be the dominant destabilizing factors. In wet granulations, basic agents, however, were found to suppress drug degradation even in the presence of moisture. Supported by the product distribution studies, the stabilization is proposed to involve the neutralization of the acidic drug by the basic excipients.
Levothyroxine sodium tablets from two different manufacturers were analysed using the USP-NF method of analysis, a stability-indicating high pressure liquid chromatographic (HPLC) procedure. The results indicate that one particular manufacturer's 0.2-mg pink tablets contain some excipient(s) which act as a catalyst to hasten decomposition after extraction of levothyroxine for analysis. The same tablets from a different batch showed an additional long peak in the chromatogram, which indicated that the excipient(s) may have been changed. The same manufacturer has also used three different types of bottles/lids for the same product during the last year. Good manufacturing practice requires that new compatibilities/stability studies be conducted to assure the quality of the product. Ongoing stability studies are required by the Food and Drugs Administration (FDA). The use-life of 0.2-mg pink tablets of this manufacturer may be short.
The effects of the addition of the excipients sorbitol, sodium lauryl sulphate and Aerosil on the physical properties of a paracetamol tablet formulation have been evaluated. Increase in the concentration of sorbitol and sodium lauryl sulphate caused a decrease in the hardness with a corresponding increase in the friability, disintegration and dissolution rates of the tablets. The mode of incorporation of the excipient, Aerosil, greatly influenced the physical properties of the paracetamol tablets. When added internally, the tablets' strength decreased while the friability, disintegration and dissolution rates increased. However, when Aerosil was added externally, the strength of the tablets increased while their friability, disintegration and dissolution rates decreased.
The topical tolerability of the commercial preparation of 1-7 Asu-eel and salmon calcitonin with 2% ammonium glycyrrhyzinate and 0.01% benzalkonium chloride, respectively, and of their excipients mixture in solution with increasing concentrations of ammonium glycyrrhyzinate and benzalkonium chloride, respectively, were assessed by investigating their effects on the mucociliary transport velocity in the ex-vivo frog palate preparation. This preparation provides an integrated biological model readily usable in the laboratory which closely resembles human nasal mucociliary clearance mechanism and can be used for rapid testing and toxicity of agents proposed for topical administration in the upper and lower airways. Frog-Ringer control, 1-7 Asu-eel and salmon calcitonin commercial spray preparations and the excipients plus 2% ammonium glycyrrhyzinate and plus 0.01% benzalkonium chloride did not modify significantly the mucociliary transport velocity, confirming their very good tolerability on ciliated epithelium. Higher concentrations of ammonium glycyrrhyzinate (10 and 20%) caused significant slowing, on average -32 and -55%, respectively. Higher concentrations of benzalkonium chloride (0.05 and 0.1%) also caused significant slowing, on average, -43.5 and -87%, respectively.
A 5-year-old child receiving valproic acid syrup for seizure control developed diarrhea probably from the excipient ingredients. Each 5 mL of valproic acid syrup contains sucrose 3 g, glycerin 0.75 g, and sorbitol 0.75 g, providing daily amounts of 36, 9, and 9 g of sucrose, glycerin, and sorbitol, respectively. The diarrhea resolved when the child was switched to another valproic acid product. Clinicians should be aware of potential problems that may occur from excipient ingredients in pharmaceutical products when evaluating adverse effects of medications.
The influence of excipients, used in tablet technology, and technological processes on cholecalciferol (1) stability was investigated. It was observed that 1 degrades in the presence of some excipients. The stability of 1 may be increased by antioxidant addition. The best stabilizing effect was achieved by a alpha-tocopherol and ascorbic acid mixture. On the basis of the achieved results, tablets with 1 were prepared. Their physical and chemical properties, the content of 1, its stability and its pharmaceutical availability were determined.