There are many factors that influence the metabolism and excretion of drug. In some people, the process is more rapid than others while some take a much longer duration to eliminate the drug. This is due to certain variables that act to discriminate the time intervals.
Two individuals taking the same amount of drug may eliminate at different time intervals. It is due to the following factors.
- Age:A young individual has a better physiological health, liver, and kidney functioning so he is capable of metabolizing and excreting at faster rates as compared to elderly people.
- Body parameters:The height and weight of a person also alter the rate of drug elimination. The larger an individual, the more efficient and faster is the metabolism as compared to a smaller individual in terms of height and weight.
- Genetics:The genetics play an important role in regulating the enzymes of the body. People exhibiting the alleles for CYP2D6 gene are called as rapid metabolizers as their metabolism is faster than other people.
- Liver and kidney function: They are the organs directly involved in the various processes to excrete the drug out of the system. Optimum functioning is necessary for a faster rate. Any malfunctioning due to a disease process or trauma can slow down the rate. The prolonging of clearance time is further dependant on the degree of impairment.
- Basal Metabolic Rate (BMR): Though BMR plays a significant role in the clearance process. However, people having a faster BMR tend to eliminate the drug more rapidly than other people.
- Urinary pH: It plays a major role as the drug gets absorbed from the kidney tubules and keeps circulating in the system before it can be finally excreted out of the system. Acidic pH prevents the recirculation and excretes maximum drug at each time. Care should be taken while taking acidifying agents as they can lead towards acidosis, which can be a harmful condition.
Frequency of drug ingestion:
The more frequently the drug is consumed, more it has the chances to get accumulated in the body. The body has a certain capacity to metabolize drug at a single time. Taking the drug over and over again will slow down the metabolism and excretion of Codeine.
Co-administration of medicines:
Some drugs act as the inducers of hepatic enzymes and many drugs act as inhibitors. Rifampicin and Dexamethasone can expedite the metabolism of Codeine. Amiodarone, Clomipramine, Celecoxib, Haldol, and Diltiazem act as CYP2D6 inhibitors and slow down the metabolism of Codeine.
Dosages of Codeine:
Higher doses require more time to get cleared from the system. This results due to storage of Codeine inside the body.
Duration of use:
The longer durations of abuse lead to a slower metabolism and excretion process of Codeine.