Bioequivalence and Bioavailability Forum

Hi Dixit,

❝ Suppose a study is done on Lorazepam 2.5 mg, a Benzodiazepine, considering a wash out of 07 days (half life 9-16 hrs) and if the test gives a positive result in Period II, should the volunteer be included in the study or excluded.

This is really a difficult case if you do not have SOPs or a protocol that deal with this situation.
Can you tell why the drug screen is used prior to p2? Is there wording anywhere that describes what a positive result prior to p2 means?

Anyways, if you have reason to believe the subject has taken BZ's in the washout period then I'd discard the subject. Note that although the Helsinki dec protects vulnerable people, the term vulnarable was mainly ment to designate people whose rights are compromised (drug abusers not necessarily in that category), so exclusion on basis of vulnerability is perhaps not a good argument for exclusion in this case.
I would exclude if you have proof that the BZ is not Lorazepam. If you consider it ethically acceptable and technically feasible, then dose the subject and run additional analyses to ID the BZ (-metabolite) and decide later on basis of the ID. but note that depending on how your informed consent was worded and the info given when the subject signed you could be in a situation where such an analysis is not considered appropriate.

In hindsight this might be something to learn from, especially the use and usefulness of a BZ test prior to p2.

Whatever you do, your choice is likely to be disputed by someone
Since the CV for Lora is not frighteningly high I guess you might end up being asked for both analyses, without much danger involved.

Dear Mr Dixit,

❝ Suppose a study is done on Lorazepam 2.5 mg, a Benzodiazepine, considering a wash out of 07 days (half life 9-16 hrs) and if the test gives a positive result in Period II, should the volunteer be included in the study or excluded.

The protocol for bioequivalence studies with Benzodiazepines, Barbiturates will usually include a statement that "If the subjects shows positive results in Urine Drug of Abuse for the drug class which is under Bioequivalence investigation, then additional quantitative test or specific qualitative test for drug under investigation (in your case Lorazepam) in the urine will be estimated to ascertain the eligibility of the subject to continue the study or not."
If the qualitative test for Lorazepam or quantitative test for Lorazepam shows positive, then you need to exclude the subject from the study.

Dear Dixit,

First of all I would suggest you to have a look at the package insert or whatever document you have which describes the test you use for drugs of abuse screening. What follows also comes in part from my memories of days at university and in hospital labs, and may need to be checked against more recent and reliable sources

Urine tests for drugs of abuse, as far as I know, are immunological tests using an antibody directed against nordiazepam, the main metabolite of diazepam and a metabolite common to a number of benzodiazepines. The cross-reactivity of the antibody with other molecules varies from one reagent to the next (different vendors using different antibodies) and from one benzodiazepine to the next: some will be as well recognised as nordiazepam or even better, some others will be very poorly recognised, or even not at all. Benzodiazepine are a large family of molecules with a complex metabolism.

The concentration found in urine is also very variable depending on the molecule, as the dose administered varies over 10-fold from one molecule to the next. You may get a positive result with a therapeutic dose of one molecule, and a negative test with an overdose of another molecule.

Remember also that your urine test for benzodiazepines was not primarily developed to screen healthy volunteers, but rather for medical applications where the question is more to detect an abuse of a drug, not a normal use at a pharmacological level.

❝ Traces of Ativan can be found in urine for at least a week, even at small doses. Sometimes Ativan can be detected for up to a month and a half after use.

Yes, sure, with LC-MS/MS, but with your test ?

❝ Of course, Ativan detection depends on the dose of Ativan taken, and if it’s been taken frequently in the past. Ativan addicts and abusers will have a harder time clearing this drug from their system, even after they completely quit taking Ativan.

Which would not be the case in your situation, after a single-dose administration... Unless the test you are using has a very high sensitivity for lorazepam, I would consider a positive result after a 7-day washout period to be unlikely to be related to the drug given in Period I.

Now I can see two options:

- you consider that the subject is testing positive because he took some benzodiazepine between the two periods, you consider this as a protocol violation, and you exclude the subject. Regulators may accuse you of having excluded a subject showing abnormally high concentrations of lorazepam in Period I, and residual concentrations in Period II... It would be safer to analyse Period I samples even though the subject was excluded, to prove this was not the case. Also possibly to collect and analyse the pre-dose sample of Period II. If you do find high concentrations, but you have excluded the subject, you're in trouble;

- you consider that it may be due to the drug in Period I, or to a protocol violation, and you can't be sure. One possibility would be to proceed with Period II normally, and to make a decision after analysing the pre-dose sample in Period II: if you find lorazepam it may be due to the administration in Period I; if you don't find any lorazepam then the subject took another product and is a protocol violator. I would analyse the pre-dose sample in Period II before all other samples from that subject and make a decision at this stage, so that regulators can't accuse you of eliminating data you don't like.

Of course an ideal situation would be to be able to identify which benzodiazepine the subject took, before dosing in Period II, as suggested by ElMaestro and Dr Gunasakaran. But this would only leave you a few hours between check-in in the evening and dosing in the next morning.

Define in your protocol what you will do...

Regards
Ohlbe