1. A factor that influences the absorption of a drug is the drugs lipophilicity. This can influence the onset of action of the drug and the extent of the effects that the drug will have on the Central Nervous System. Drugs with a high lipophilicity will have a rapid onset of action and will have a greater effect on the CNS whereas drugs with a lower lipophilicity will have a slower onset of action and has minimal effects on the CNS because these drugs cannot cross over the blood brain barrier as effectively as drugs with a high lipophilicity.

2. Redistribution of a drug is when the drug is absorbed into the systemic circulation and then transported to other tissues in the body. This process helps to prolong the duration of action of the drug.

3. Benzodiazepines are metabolized by the hepatic microsomal enzymes in a three-step process:

• Dealkylation to active metabolites.
• Oxidation via the CYP-P450 enzymes to active metabolites.
• Conjugation with glucuronic acid to form inactive, water-soluble metabolites.  

4. Benzodiazepines that are converted to an active metabolite known as Desmethyldiazepam, these include: Diazepam, Chlorazepate, Prazepam, Chordiazepoxide and Ketazolam.

Drugs that are converted into an active metabolite can increase the duration of action but can also result in cumulative effects with multiple doses.

5. Benzodiazepines that are not dependent of the CYP-P450 enzyme for metabolism include: oxazepam, lorazepam, temazepam, lormetazepam. These drugs provide an advantages for patients with liver cirrhosis, elderly patients, neonates as well as patients that use CYP-P450 enzyme inhibitors for these drugs do not affect the levels of CYP-P450 in the body because it does not require the enzyme to elicit its effect.

6. Enzyme induction is when a drug results in the increased production of certain enzymes that will increase the rate of metabolism of the drug. This process is seen mostly with older Barbiturates such as Phenobarbital and Meprobamate.  Enzyme induction causes a decrease in the amount of drug in the systemic circulation which will cause a decrease in the therapeutic effects of the drug.