As already mentioned, Ambien has a half-life of two to three hours. The complete drug will take about 14 hours to get eliminated from the body. However, it is just an average figure and the time duration is highly variable among individuals, depending on many factors. Such factors include individual attributes, dosages, co-administered agents, frequency and duration of use.
These include age, body mass, genetics, hydration, liver and kidney functions.
- Age: The clearance process is slower in an elderly person due to lower levels of free testosterone, reduced hepatic flow, and concomitant use of medicines for other health conditions. Younger people have higher metabolization and excretion rate of Ambien than elderly individuals.
- Body Mass: People having a larger body mass are capable of metabolizing and excreting the drugs at faster rates. A large individual having a tall height will excrete the drug sooner than his counterpart having a small height and low weight.
- Genetics:The genetics also play a role in determining the duration of a drug clearance from the body system. Individuals carrying CYP3A4’18 allele have more expression of CYP3A4 isoenzymes. These are involved in the basic metabolism of Zolpidem. Enhanced expression leads to a faster metabolism. Where as individuals expressing CYP2C19’2 have slower rates of metabolism.
- Food intake:The absorption rate of drug is slower on a full stomach than an empty stomach. Moreover, some foods can also affect the absorption time of Zolpidem.
- Liver Functions: Hepatic enzymes are involved in the process of metabolism. Any impairment of liver processes can slow down the metabolism. It has been found that the half-life of Zolpidem was extended to 10 hours in the cirrhotic patients.
- Basal Metabolic Rate (BMR):People having a high BMR burn more energy during rest so they are capable of metabolizing Zolpidem faster than people with a low BMR.
- Sex: It also plays a role in the case of Zolpidem. Men have higher metabolizing rates than women. It is based on higher testosterone levels in males.
- Urinary pH: The acidic pH prevents the reabsorption of Zolpidem through the kidney tubules so the whole of the drug gets excreted. Individuals exhibiting alkaline pH have a slower rate of drug elimination through urine. The pH, in turn, is dependent on the type of food eaten by a person. Carrots, limes, dates, and fig turn the pH towards alkalinity.
The higher the doses taken by a person, the more is the time taken by the elimination processes. Larger doses take more time to get metabolized and get excreted. More amount of a drug is circulating through the body and makes a person susceptible to reabsorption process through the kidney tubules.
Co-administration of drugs:
Many medicines and supplements can affect the liver enzymes. Some of the drugs can enhance the rate of metabolism while others tend to slow it down. Drugs like Indinavir, Ritonavir, Clarithromycin, Ketoconazole, and Nelfinavir have inhibitory effects on liver enzymes. Carbamazepine, Phenobarbitol, Oxcarbamazepine, and Rifampicin tend to enhance the functioning of liver enzymes.
Frequency and Duration:
The frequent administration of drug results in higher accumulation and slower excretion of Zolpidem. Duration of use also contributes towards the drug elimination time from the body. The longer duration leads to a more prolonged drug clearance.