Toxicity Information and Courses from MediaLab, Inc.

Can all drugs benefit from TDM? Not really. For TDM to be effective and useful, one or more of the following should apply: The effective concentration and toxic concentrations must be well-defined. The pharmacokinetics of the drug are known to be variable. The drug is given chronically. There is the potential for drug-to-drug interactions. The drug exhibits high protein binding. The toxicity will mimic the indication for the drug; toxicity may not be visible during an exam but will only be revealed with TDM. The patient is pregnant, very young, or elderly. Compliance or history with the drug is poor.

When discussing PGx, we classify a person according to his/her phenotype (metabolic capacity for a given enzyme).A poor metabolizer (PM) is a person who lacks the functional enzyme and therefore exhibits decreased metabolism of drugs. This person would require lower doses of a drug that is metabolized by that enzyme. A PM who receives a standard dose is more likely to experience unwanted side effects or toxicity. A PM can also experience diminished effects with drugs that need to be metabolized to active compounds by the enzyme in question.An ultrarapid metabolizer (UM) will require a higher dose than usual since he/she will eliminate the drug more quickly. A UM may be resistant to standard treatments, and it may take some time to adjust the dosage before therapy is achieved.An intermediate metabolizer (IM) has one wild-type (normal) copy of the gene and one absent or dysfunctional copy. The IM group is very heterogeneous.A person with normal enzyme activity is referred to as an extensive metabolizer (EM). This person should respond to standard dosages of a drug. Most people are EM's. This is the population in which most dosing regimens have been worked out in clinical trials.

Accurate semen analysis results require appropriate sample collection. Patients must receive detailed directions for proper specimen collection and transport. Directions should be in writing. Specific instructions should include: The period of abstinence prior to collection should be between 2 and 5 days.The entire specimen must be collected because the different portions have varying concentrations of spermatozoa.An appropriate collection container must be used.Each laboratory should designate an appropriate, wide mouth, collection container.Each lot of collection containers should be tested to ensure that it is non-toxic to sperm.Alternative collection containers should be discouraged because their level of toxicity is unknown.Use of condoms for collection should be discouraged particularly when the purpose of the semen analysis is to test for fertility. Some condoms are toxic to sperm. Collection in condoms often results in inaccurate results for semen volume and other parameters.