الفهرس 
ACKNOWLEDGMENT
Plasma liporoteinsOnly 14 pages are availabe for public view
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Abstract
Studies on the protein binding of cationic drugs suggested that, in some acute clinical conditions, drug therapy is more effectively monitored by free drug levels. This is especially true for calcium channel blockers e.g. verapamil (VER) and nilvadipine (NV) and (3-blocker propranolol (PRO ),. This work was undertaken fundamentally to evoke a suitable reliable method for studying the binding of these drugs with plasma lipoproteins and for monitoring their free plasma levels. Capillary electrophoresis coupled with frontal analysis (HPCE/FA) was applied to the ultramicro and enantioselective binding study of plasma lipoproteins to PRO , VER and NV. The drug - lipoprotein mixed solution was introduced hydrodynamically into non-coated fused silica capillary. Due to electroosmotic flow, unbound drug enantiomer S- or -R, a neutral or positively charged compound, migrates toward cathodic end faster than negatively charged and the bound form. Once unbound drug migrates apart from lipoprotein, the bound drug is quickly released from the protein to maintain the binding equilibrium. Then, the drug migrates as a zone with a plateau region, and the concentration in this plateau region is the same as the unbound drug concentration in the sample solution. The factors which affect on the application of HPCE/FA were optimized. These factors include, effect of voltage, effect of sample injection time and the velocity of LDL and HDL. For all the ”investigated drugs, the binding to high-density lipoprotein (HDL), low-density lipoprotein (LDL) is non-specific, and no enantioselectivity was observed in these bindings. Partition-like binding to lipid phase ofthese lipoproteins seems to be dominant. The unbound fraction is constant for each drug enantiomer and the two enantiomers of the drug have almost the same unbound fraction value. The R/S ratio of the unbound concentration was almost unity, so this mean no enantioselectivity. The total binding affinities (nk) of LDL [LDL containing the higher lipid fraction (ca.80%) than HDL] to PRO, VER and NV is usually stronger than those of HDL , which also supports that the binding to the lipid phase is dominant in drug (PRO, VER and NV) - lipoprotein binding. The total binding affinity of PRO to LDL was about 17 times higher than that of PRO - HDL binding . In case of NV and VER (nk) value of LDL are about seven times stronger than those of HDL .The unbound drug concentrations of PRO and NV enantiomers in HDL and LDL solutions calculated from the plateau height were compared with the free drugs determined by HPCE/ FA and a conventional ultrafiltration. Both methods gave almost the same results indicating the reliability of the developed method. However, HPCE/FA method has the advantage that the sample injection volume (ca. lOOnL) is much smaller than that used in the conventional methods by about two orders of magnitude. Because of the small injection volume, the present method is useful for the binding study of plasma lipoproteins of which the long-term preservation and large-scale preparation are difficult. Oxidized Low density lipoprotein (oxidized LDL) is believed to be an early event in the initiation and progression of atherosclerosis .No report about the binding of oxidized LDL with drugs, especially which used in cardiovascular disorders and their pharmacological actions which depend on the free drug concentration. Study of NV and VER binding with oxidized LDL were carried out using HPCE/FA. The oxidation increased the drug affinity of LDL markedly. The unbound drug fraction in oxidized LDL solution is much smaller than in the same concentration of native LDL solution. The (nK) value of NV - oxidized LDL binding was about 20 times stronger than native LDL. In case of VER the affinity was enhanced by about 10 times after the oxidation of LDL i.e, the binding between NV and the oxidized LDL is more stronger than that of VER-oxidized LDL. As for both drugs (NV, VER) the binding to high-density lipoprotein (HDL), low-density lipoprotein (LDL) and oxidized LDL is non-specific, and enantioselectivity was not observed in these bindings. Partition-like binding to lipid phase of these lipoproteins seems to be dominant. The oxidation of LDL enhanced the binding affinities significantly. Although several drugs have been shown to bind to Iipoproteins(LPs), little is known about which component of (LPs) is the binding site. The binding of S or R VER with apolipoprotein -B is studied using HPCE/FA. The results showed that, no difference between the plateau height of VER alone or with apolipoprotein-B. This mean that VER, is not bound to the surface apoproteins and no enantioselectivity because no difference in the binding between S and R- VER with apolipoprotein-B. from the results of this dissertation the following conclusions can be made:-
1- High performance capillary electrophoresis/ frontal analysis is more sensitive, rapid and precise than conventional technique for study of drugs binding to plasma lipoproteins.
2-The unbound percentage for PRO, VER and NV with LDL are 57, 72.7 and 21.6 % respectively.
3- The unbound percentage for PRO, VER and NV with HDL are 74, 71 and 18.9 % respectively.
4- The binding between lipoproteins with (R and S) of PRO VER and NV is non selective.
5-The total binding affinity (nk) for PRO VER and NV with LDL is higher than with high density lipoprotein HDL.
6- The total binding affinity (nk) for PRO VER and NV with oxidized LDL is higher than with native LDL.
7- The binding between VER and LDL occurs in the lipid part of the lipoprotein and no binding with the apolipoprotein- B.LDL. As for both drugs (NV, VER) the binding to high-density lipoprotein (HDL), low-density lipoprotein (LDL) and oxidized LDL is non-specific, and enantioselectivity was not observed in these bindings. Partition-like binding to lipid phase of these lipoproteins seems to be dominant. The oxidation of LDL enhanced the binding affinities significantly. Although several drugs have been shown to bind to Iipoproteins(LPs), little is known about which component of (LPs) is the binding site. The binding of S or R VER with apolipoprotein -B is studied using HPCE/FA. The results showed that, no difference between the plateau height of VER alone or with apolipoprotein-B. This mean that VER, is not bound to the surface apoproteins and no enantioselectivity because no difference in the binding between S and R- VER with apolipoprotein-B. from the results of this dissertation the following conclusions can be made:-
1- High performance capillary electrophoresis/ frontal analysis is more sensitive, rapid and precise than conventional technique for study of drugs binding to plasma lipoproteins.
2-The unbound percentage for PRO, VER and NV with LDL are 57, 72.7 and 21.6 % respectively.
3- The unbound percentage for PRO, VER and NV with HDL are 74, 71 and 18.9 % respectively.
4- The binding between lipoproteins with (R and S) of PRO VER and NV is
non selective.
5-The total binding affinity (nk) for PRO VER and NV with LDL is higher than with high density lipoprotein HDL.
6- The total binding affinity (nk) for PRO VER and NV with oxidized LDL
is higher than with native LDL.
7- The binding between VER and LDL occurs in the lipid part of the
lipoprotein and no binding with the apolipoprotein- B.