Rickettsia, which is duly placed in the order Rickettsiales and family Rickettsiaceae of the αlpha-proteobacteria ; whereas, Coxiella is shown in the order Legionellales and family Coxiellaceae of the γ-proteobacteria. Based upon their close and intimate similarity in the ‘life-style’, despite their apparent ‘phylogenetic distance’, these two genera shall be discussed together.

Salient Features : The salient-features of Rickettsia and Coxiella are as enumerated under:
(1) The bacteria belonging to these two genera are found to be rod-shaped, coccoid, or pleomorphic having typical Gram-negative walls and devoid of any flagella; however, their actual size usually varies but they tend to be relatively very small. Read the rest of this entry »

Application of pharmaceutical principles to drug dosage forms is illust rated when drug dosage forms are categorized according to their physical state, degree of heterogeneity, and chemical composition. The usual relevant states of matter are gases, liquids, and solids. Intermolecular forces of attraction are weakest in gases and strongest in solids. Conversions from one physical state to another can involve simply overcoming intermolecular forces of attraction by adding energy (heat) . Chemical composition can have a dramatic effect on physicochemical properties and behavior. For this reason, it is necessary to distinguish between polymers, or macromolecules, and more conventional ( i .e., smaller) molecules, or micromolecules.
check-tools.com
Read the rest of this entry »