Peak and Half-Life

• Peak is how long it takes for a drug to be at its highest concentration in your bloodstream (based on a single dose) and how long the drug is at full effect in terms of pain relief. Half-life is how long it takes half the dosage of the narcotic administered to be eliminated from your system. According to U.S. Pharmacy, a continuing educational site for pharmacy technicians and pharmacists, morphine is the "gold standard" against which other narcotics are measured for half-life and peak. Most narcotic analgesics peak anywhere from one to two hours with an average half-life from two to four hours. Hydrocodone and oxycodone (Vicodin and OxyContin or Percocet) take a little longer than the norm to peak at two hours or longer. Morphine has the shortest half-life at two hours, with meperidine (Demerol) and extended-release drugs exceeding three to four hours. (See Reference 2, Table 4; category "po" refers to pill form rather than injectable)
  
  

Toxicology Screens

• Toxicology (tox) screens are performed through testing urine, blood, saliva or some combination of all three. Tox screens are not used to determine how long you have been using narcotics or how frequently; they are designed only to ascertain if you are using certain medications at the time of the test. Factors that can affect or skew tox screen results are weight, age and metabolic rate, to name a few. According to Craig Medical, the chronic use of particular narcotics, low metabolic rate and high BMI (fat index) will cause you to screen on the higher end of the scale. By and large, most opiates such as heroin and morphine will clear your system in two to three days. OxyContin and Percocet, because they are synthetics, should clear in one to two days. (See Reference 3)
  
  

Withdrawal

• Withdrawal is the term for the physical and psychological effects that you suffer when a drug upon which you are dependent leaves your system. According to the Department of Justice and the Drug Enforcement Administration, medications like morphine and heroin will cause shorter, more intense physical withdrawal. Longer acting or timed-release narcotics will have a longer physical withdrawal period. Symptoms usually start right before it is time for your next dose of the medication. Physical withdrawal will usually last from seven to 10 days. If the underlying physical condition and the psychological addiction are not treated, relapse is quite common. (See Reference 4)