ABSTRACT
RUDY L. JULIANO / Univers i ty of Texas Medical School, Houston, Texas
I . Introduct ion 556
I I . Preparat ion of Drug Containing Microparticulates 557
A. Liposomes 557 B . Microspheres 558 C. Cells 559
I I I . In Vivo B a r r i e r s to Microparticulate Distr ibut ion 561
A. The Endothelial Ba r r i e r 562 B . The Reticuloendothelial (RE) System Bar r i e r 563 C. Cellular B a r r i e r s 564 D. Factors Affecting the Clearance and
Distr ibution of Microparticulate Car r i e r s 565 IV. Selected Examples of Drug Delivery with
Microparticulate Ca r r i e r s 566
A. Liposomal Immunomodulators 566 B . Reduction of Toxicity of Antitumor Drugs
Using Liposomes 568 C. Liposomes in the Therapy of Obligate and
Facultat ive Intracel lular Pathogens 568
D. Antitumor Drugs in Microspheres 570 E. Red Cells as Enzyme Car r i e r s 571
V. Summary 571
References 572
I. INTRODUCTION
The behavior of d r u g s in vivo can often be changed in dramatic fashion by coupling the d r u g to a c a r r i e r moiety. The plasma clearance k ine t i c s , t i s sue d i s t r ibu t ion , metabolism and cellular in te rac t ions of the d r u g will be d ic ta ted , or at least s t rongly influenced, by the behavior of the c a r r i e r . In some ca se s , judicious exploitation of these changes in pharmacodynamic behavior can lead to an enhanced the ra - peutic index for the d r u g . However, an intell igent approach to the rapeu t ics us ing d r u g - c a r r i e r technology r equ i r e s a detailed u n d e r - s tanding of the interact ion of the ca r r i e r with critical cellular and organ sys tems .
