A semilog graph paper is a graph paper in which the x-axis is a normal linear scale, but the y-axis is a logarithmic scale. Semilog graph paper allows plotting the data at logarithmic intervals without the need for logarithmic transformation.

The y-axis is divided into cycles, each represents 10-fold increase in values (a single log₁₀ unit).

The semilog graph paper allows plotting the data at logarithmic intervals without doing the actual logarithmic transformation of the numbers.

In order to determine the slope of a line drawn on a semilog graph paper it is necessary to do logarithmic transformation for the y values. The slope of the line in this case will be determined from the following relationship:

The first-order absorption rate constant is the rate constant that determines the rate of drug absorption from the site of administration. Larger absorption rate constant results in faster rate of drug absorption.

The absorption rate constant determined after drug administration is an operative rate constant that accounts for all the necessary steps required for drug absorption into the systemic circulation including disintegration, dissolution and absorption.

The first-order absorption rate constant has units of time^-1.

The half life of any process is the time required for the process to reach 50% completion. The half life of the absorption process is the time required for half the bioavailable dose to be absorbed.

The absorption half life is constant (dose independent) when drug absorption follows first-order kinetics.

The absorption half life has units of time.

Drugs with shorter absorption half lives are absorbed faster than those with longer absorption half lives.