P. Kása

The compressibility and compactibility of different types of lactose

Objective: The purpose of this study was to investigate and quantify flow properties, compressibility, and compactibility of various pharmaceutical lactose powders found on the market today (DCL-11, DCL-21, M‐200, Flowlac-100, and Tablettose 70, 80, and 100). Methods: Flow properties were estimated by measuring flow time, angle of repose, and the Hausner ratio. Particle rearrangement was studied using Kawakitas linear model. Compressibility was studied using two ‘out-of-die’ methods: (i) the Heckel model and (ii) a modified Walker model. Compactibility was quantified using two methods: (i) the tensile strength profile (Cp) and (ii) the compactibility factor (Pr). Statistical approach was used to analyze the results. Results: Flow properties of all materials were passable or better, except for M-200, which has very poor flowability. Compressibility results demonstrated that the most compressible lactose is spray-dried grade of lactose (Flowlac-100) and the least compressible is milled lactose (M-200). Compactibility studies showed that β‐lactose (DCL-21) forms tablets with superior tensile strength in comparison with α-lactose. Conclusion: Results of the compressibility study showed that the discriminative power of modified Walker model is greater in comparison with Heckel model. Compactibility methods yield similar and comparable results.

Type A and B gaba receptors mediate inhibition of acetylcholine release from cholinergic nerve terminals in the superior cervical ganglion of rat

The effects of ?-amino-n-butyric acid (GABA), (+)bicuculline, isoguvacine and 3-(4-chlorophenyl)-4-aminobutyrate [(+/-)baclofen] on the K-induced release of [(3)H]acetylcholine (ACh) were studied in the superior cervical ganglia of the rat in vitro. GABA and isoguvacine inhibited [(3)H]ACh release and these inhibitions were reversible by (+)bicuculline. Furthermore, the release of [(3)H]ACh was also inhibited by (+/-)baclofen. In receptor-binding studies, binding of [(3)H]GABA to membrane preparations from the superior cervical ganglia was inhibited by both (+/-)baclofen and (+)bicuculline. It is concluded that the inhibitory effect of GABA on the release of ACh can be mediated by GABA(A)(bicuculline-sensitive) and by GABA(B) (baclofen-activated) receptors. Our findings are compatible with the existence of a non-synaptic GABAergic inhibitory system involving GABA(A) and GABA(B) receptors on cholinergic nerve terminals in the superior cervical ganglion of rat.

Postnatal development of the acetylcholine system in different parts of the rat cerebellum.

Abstract: The components of the cholinergic nervous system, i.e., choline acetyltransferase, acetylcholinesterase, sodium‐dependent high‐affinity choline uptake, acetylcholine, and the muscarinic acetylcholine receptors, in the developing archi‐ and paleocerebellum of the rat have been investigated by biochemical methods. A close correlation between the development of the different elements of the system has been demonstrated in the two areas. The cholinergic structure develops first in the archicerebellum, which displays high levels of choline acetyltransferase, acetylcholinesterase, acetylcholine, and sodium‐dependent high‐affinity choline uptake. The paleocerebellum receives a sparser cholinergic innervation during development. The differences in the values for these components in the cerebellum as a whole may reflect the development of cholinergic and noncholinergic neuronal structures. It is concluded that the development of the cholinergic system cannot be analyzed in the cerebellum as a whole; rather specific regions such as the archi‐, paleo‐, or neocerebellum must be examined.

Modulation of the acetylcholine system in the superior cervical ganglion of rat: Effects of GABA and hypoglossal nerve implantation after in vivo GABA treatment

Abstract: γ‐Aminobutyric acid (GABA) was applied to the superior cervical ganglion (SCG) of CFY rats in vitro and in vivo, with or without implantation of a hypoglossal nerve, to evaluate the effects of these experimental interventions on the acetylcholine (ACh) system, which mainly serves the synaptic transmission of the preganglionic input. Long‐lasting GABA microinfusion into the SCG in vivo apparently resulted in a “functional denervation.”This treatment reduced the acetylcholinesterase (AChE; EC 3.1.1.7) activity by 30% (p < 0.01) and transiently increased the number of nicotinic acetylcholine receptors, but had no significant effect on the choline acetyltransferase (acetyl‐coenzyme A:choline‐O‐acetyl‐transferase; EC 2.3.1.6) activity, the ACh level, or the number of muscarinic acetylcholine receptors. The relative amounts of the different molecular forms of AChE did not change under these conditions. In vivo GABA application to the SCG with a hypoglossal nerve implanted in the presence of intact preganglionic afferent synapses exerted a significant modulatory effect on the AChE activity and its molecular forms. The “hyperin‐nervation”of the ganglia led to increases in the AChE activity (to 142.5%, p < 0.01) and the 16S molecular form (to 200%, p < 0.01). It is concluded that in vivo GABA microinfusion and GABA treatment in the presence of additional cholinergic synapses has a modulatory effect on the elements of the ACh system in the SCG of CFY rats.

Transport of muscarinic cholinergic receptors in the sciatic nerve of rat

On the basis of the specific [(3)H]quinuclidinyl-benzilate binding, the transport of muscarinic cholinergic receptors has been demonstrated in the ventral horn, sciatic nerve and in the 3 mm segments proximal and distal to the ligature of rat sciatic nerves ligated for 24 h (a) without electrolytic lesion, (b) six days after lesion of the spinal ganglia, (c) six days after lesion of the motoric axons, and (d) six days after transection of the sciatic nerve. The distribution of these receptors was also studied in the ventral spinal horn, dorsal root sensory axons, spinal ganglia and sciatic nerve of rabbit. Our results suggest that the receptors are transported in the sciatic nerve of rat. This transport consists of a large anterograde, and a discrete retrograde flow of muscarinic cholinergic receptors. Most of the receptors are possibly synthesized in the motoneuron cell bodies and migrate in the motoric axons; to a lesser extent they may also be synthesized in the cell bodies of the dorsal root ganglia and migrate in the sensory axons of the sciatic nerve.

In vivo effects of β-bungarotoxin on the acetylcholine system in different brain areas of the rat

Abstract: The in vivo effects of β‐bungarotoxin (β‐BT) on the acetylcholine (ACh) system were studied in the whole cerebrum and in different brain regions. The effect of β‐BT on cerebral ACh and choline (Ch) contents was time‐dependent. The results show that a singe intrace‐ rebroventricular injection of 1 μg toxin increased both the ACh and Ch contents in the cortex, hippocampus, and cerebellum, while in the striatum the ACh level was decreased. Ten nanograms of toxin injected into the lateral ventricle twice, on the first and third days, led to a reduced ACh level 2 days after the last treatment. In animals treated with the same dose three times, on the first, third, and fifth days, and sacrificed 2 days after the last injection, the choline acetyltransferase and acetylcholinesterase activities were reduced and the number of muscarinic acetylcholine receptors was decreased. A biphasic effect of the toxin was therefore demonstrated. It is suggested that in the first phase of the toxin effect the increased levels of ACh and Ch may be due to the inhibition of neuronal transmission, while in the second phase, when the elements of the ACh system are reduced, the neuronal degenerating effect of β‐BT plays a significant role.

Effect of the surface free energy of materials on the lamination tendency of bilayer tablets

Dosage forms with fixed dose combinations of drugs is a frequent and advantageous mode of administration, but their production involves a number of technological problems. Numerous interactions in a homogeneous vehicle may be avoided through the use of layered tablets. The mechanical properties of these dosage forms depend on numerous process parameters and material characteristics. The aim of the present study was a detailed investigation of the relationships between the surface characteristics and deformation properties of tableting materials and the tendency of bilayer tablets to undergo lamination. Bilayer tablets were compressed from unlubricated materials with different plastic-elastic properties and surface free energies according to a mixed 2 and 3-level half-replicated factorial design. The results revealed that the surface characteristics play the main role in the lamination of layered tablets and the effect of the plastic-elastic behavior cannot be interpreted without a knowledge of these properties.

From Mini to Micro Scale—Feasibility of Raman Spectroscopy as a Process Analytical Tool (PAT)

Background Active coating is an important unit operation in the pharmaceutical industry. The quality, stability, safety and performance of the final product largely depend on the amount and uniformity of coating applied. Active coating is challenging regarding the total amount of coating and its uniformity. Consequently, there is a strong demand for tools, which are able to monitor and determine the endpoint of a coating operation. In previous work, it was shown that Raman spectroscopy is an appropriate process analytical tool (PAT) to monitor an active spray coating process in a pan coater [1]. Using a multivariate model (Partial Least Squares—PLS) the Raman spectral data could be correlated with the coated amount of the API diprophylline. While the multivariate model was shown to be valid for the process in a mini scale pan coater (batch size: 3.5 kg cores), the aim of the present work was to prove the robustness of the model by transferring the results to tablets coated in a micro scale pan coater (0.5 kg). Method Coating experiments were performed in both, a mini scale and a micro scale pan coater. The model drug diprophylline was coated on placebo tablets. The multivariate model, established for the process in the mini scale pan coater, was applied to the Raman measurements of tablets coated in the micro scale coater for six different coating levels. Then, the amount of coating, which was predicted by the model, was compared with reference measurements using UV spectroscopy. Results For all six coating levels the predicted coating amount was equal to the amounts obtained by UV spectroscopy within the statistical error. Thus, it was possible to predict the total coating amount with an error smaller than 3.6%. The root mean squares of errors for calibration and prediction (root mean square of errors for calibration and prediction—RMSEC and RMSEP) were 0.335 mg and 0.392 mg, respectively, which means that the predictive power of the model is not dependent on the scale or the equipment. Conclusion The scale-down experiment showed that it was possible to transfer the PLS model developed on a mini scale coater to a micro scale coater.

An improved method for the bulk isolation of spinal motoneurones

Details are described of a procedure for the isolation of motoneurones from pig spinal cord in high yield and high purity. Mechanical dissociation, one low-speed centrifugation and two high-speed ultracentrifugations were applied to separate the motoneurons from other elements of the anterior horn. The first ultracentrifugation through a sucrose gradient resulted in a pellet consisting mainly of motoneurones, microvessels, free nuclei and red blood cells, whereas with the use of Ficoll 400 the motoneurones could be separate from the contaminating elements during a second ultracentrifugation. The high yield and purity of the motoneurones in the final fraction may permit further studies, in which the neurochemical properties of the spinal motoneurones can be elucidated.

The effect of 4-(1-naphthylvinyl)-pyridine on the acetylcholine system and on the number of synaptic vesicles in the central nervous system of the rat

The in vivo effects of 4-(1-naphthylvinyl)-pyridine on the activities of choline acetyltransferase and acetylcholinesterase, the levels of acetylcholine and choline, the sodium-dependent high affinity choline uptake and the number of synaptic vesicles were investigated in the rat brain. Our results indicate that 4-(naphthylvinyl)-pyridine (200 mg/kg, i.p.) reduced the acetylcholine level by 60% (P < 0.001), and the sodium-dependent high-affinity choline uptake in the CNS of rat. The combination of in vivo 4-(1-naphthylvinyl)-pyridine with a 15-min swimming stress induced an 87% (P < 0.001) reduction of acetylcholine in brain. The number of synaptic vesicles was reduced. We suggest that in vivo 4-(1-naphthylvinyl)-pyridine does reduce the steady-state level of acetylcholine, but that the reduction is due to a general effect of the drug on the acetylcholine system and membranes, rather than to a specific inhibitory action on the choline acetyltransferase activity.