Dyphenhydramine

[TE RANGI]

Dyphenhydramine is a non prescription drug often used on over the counter sleeping aids. It just came to light as it may have been contributory to an accident of an American corporate jet at BHX in 2002.

Would any fellow colleagues more in the know care to comment on the side effects of dyphenhydramine and whether it has to be avoided before (or how long before) flying.

Done a little research but couldn't find out the half life of dyphenhydramine in the human body so I don't have a clue as to what would be the required lapse between pill and duty.

Thanks.

[gingernut]

I might be stating the obvious, but have you looked here (http://www.bnf.org)

At the moment its spelt with an "I" not a "Y" in the uk.

I think you may have to register.

[slim_slag]

BNF keeping the unwashed masses out I see, musn't let the end user know what he is putting in his body huh? Shame really, it's a great resource, but the information within is readily available all over the Internet.

The mean serum elimination half-life values for diphenhydramine differed significantly in elderly adults, young adults, and children, with values of 13.5 +/- 4.2 hours, 9.2 +/- 2.5 hours, and 5.4 +/- 1.8 hours being found respectively in each age group. Clearance rates for diphenhydramine also differed significantly with age, being 11.7 +/- 3.1 mL/min/kg in elderly adults, 23.3 +/- 9.4 mL/min/kg in young adults and 49.2 +/- 22.8 mL/min/kg in children. Diphenhydramine phamacokinetics (http://www.jclinpharm.org/cgi/content/abstract/30/7/665)

So now you have the data you requested, what are you going to do with it?

[TE RANGI]

Thank you, gentlemen.

My spelling error may explain why I had found so little about it.

Now, my question would be, plain and simple whether it would be OK to take diphenhydramine as a sleeping inducer before a flight and if so how many hours should elapse depending on dosage before you are again legal/safe.

[Flyin'Dutch']

This is an antihistamine which side effect is drowsiness.

As far as I can see it is not compatible with flying. Even some of the so called non drowsy antihistamines are not cleared for flight, let alone one which is used for its drowsiness inducing propensities.

Go and see your local quack if you need something to help you sleep so that you can get properly diagnosed and treated. If that requires medication check that medication with your local AME.

FD

[Non Normal]

Not going to bore you with excessive info, so here's a simple answer (or non-answer, more like):

If you look at this http://www.cami.jccbi.gov/AAM-600/Toxicology/Drugs/Diphenhydramine.html
you'll see that the half life could be as long as 14 hours, and some people seem to be quite affected even at a relatively small amount of it, so I think your question would be quite hard to answer, although I would personally allow myself 24 hours (minimum!!) after ingesting anything like diphenhydramine before flying.

However remember, fatigue from not sleeping can be just as detrimental to performance, if not more.

At any rate, ask an AME if in doubt about anything you might consider taking.

P.S. I've no idea about the legality of diphenhydramine in flying. Ask an AME...

[TE RANGI]

Thanks to all of you for your enlightening replies.

Let me now ask you a practical question. The scenario is this:

You are in a not too comfortable hotel and have a wake up call at 4 am to report for duty at 5:30, and you're in for a 13 hour duty day (plus 2 hour discretion). You've been on the line for a few days and your sleep patterns are already messed up. You try to adjust your lifestyle the evening before and so you go early to bed, only to discover that being out of your normal routine you don't fall asleep easily. Try reading, dull TV, turn off the lights again, tension mounts because you need the sleep and the clock is ticking...anf of course, the harder you try to sleep the more difficult it becomes. Finally you doze off... about an hour before wake up. Does this sound any familiar at all?

Well, in theory you should call them sick because you're fatigued, but who ever does that? If this were the case rosters would collapse within days and the whole industry would grind to a halt.

Now, isn't beeing sleep deprived more detrimental to performance than the side effects of say diphenhydramine, if taken sufficiently in advance? What's the point of avoiding the side effect of drowsiness when you'll be even drowsier by lack of sleep?

There is also the question of the legal implications if you were involved in an incident.

Would anyone care to comment?

[Flyin'Dutch']

Diphenhydramine is not allowed to be taken when flying.

Whilst I sympathise with your situation and have no clear cut answer for it, the rules are clear and taking medication is not the answer either.

If the use of banned medication would come to light there would likely be implication as a result of that.

FD

[Non Normal]

Since Flyin'Dutch' says diphenhydramine is not allowed to be taken when flying, you'd need to seek an alternative that is permitted (I know it's easier said than done to suggest you call in "fatigued" or "sleep-deprived").

Is temazepam or zolpidem permitted in your country and if so, could they be a better option? (By the way you'll probably need a prescription for them from a doctor in your country too.)

Anyway, the Australian DAME handbook goes to say about them:

Hypnotics. Medical certificate holders should not fly or control for at least 12 hours after ingesting the sleep-inducing agent Temazepam. Medical certificate holders should not fly or control for at least 8 hours after using the sleep-inducing agent
Zolpidem. Pilots and ATCs who use Temazepam or Zolpidem should not combine these drugs with alcohol. The use of the sleep-inducing agent Triazolam is not compatible with flying or controlling duties due to its potential CNS side effects. The
use of Melatonin is not supported by CASA due to variation in its formulation and variability in its effects.

[Flyin'Dutch']

According to the AOPA US website Zolpidem is approved for occassional use, but only if the time between taking and flying is more than 48 hours.

FD

[Loose rivets]

I'm not flying now, and use Zolpidem far more than I should. But if there seems to be a fault with this product, it is that it doesn't last long enough.

I have voiced strong opinion about drugs and flying in the past; half life calculations leave me bewildered for instance, but that old Westclocks still clangs around in my brain from a time before digital electronic alarms...most times, it started running around on top of the cabinet, just as I was finally getting to sleep. It just cannot be safe flying tired, and there can't have been a week that I wouldn't have been better off with some help to sleep on one of the duty periods.

[TE RANGI]

Flyin'Dutch':

That settles it, then. Rules are rules. And of course my only source of income is nothing to trifle with. Your simpathy however much appreciated does little to solve this problem.

Non Normal:

Again thank you for your valuable information. I will look further into the matter. Why hypnotics are preferable to antihistamines is something I find difficult to understand. Is it because their side effects die away sooner? Aren't these drugs creating some form of addiction in the long run?

Loose Rivets:

I feel you understand the problem better than anyone else as you've probably walked the walk before. As you know, in the airline world sleep is no laughing matter. I'm surprised at the lack of help to counter the effects of desynchronization, which in a cost driven environment will only get worse.

Maybe this issue which affects just about every professional aviator has only been dealt with with a considerable dose of hypocrysy. Perhaps your practical knowledge of the matter might shed some light.

[Non Normal]

Why hypnotics are preferable to antihistamines is something I find difficult to understand. Is it because their side effects die away sooner? Aren't these drugs creating some form of addiction in the long run?



I don't know the aviation authorities' reasoning for sure, but I think it is safe to guess that the shorter duration of action is at least one of the reasons for their prefererence for some (definitely not all hypnotics though!) shorter acting hypnotics to antihistamines. (Both zolpidem and temazepam are fairly short acting.)

Also, everything you read about hypnotics does state that they should not be used all the time or long-term. Zolpidem has a lesser dependence potential than temazepam from what I have read.

Flyin'Dutch might know more...

[Flyin'Dutch']

Although less addictive than any of the other benzodiazepines even zolpidem can be addictive.

I think the main reasons why the authorities are unkeen on these drugs are that they can interfere for some time with higher cognitive functions and reactive times due to the propensities of the drug itself and their (active) metabolites (the bits in which it falls apart when your body is trying to get rid of it)

Furthermore these drugs do help people to get off to 'sleep' but the complex sleep and restoration project is more than the dozing off which these drugs achieve.

[f40]

To paraphrase TE RANGI, an issue which affects just about every professional aviator and flight attendant and has only been dealt with with a considerable dose of hypocrysy.
Everyone in civil aviation will instantly recognise TR's desciption of sleeplessness in a hotel bed, and the desperation it can induce.

Despite the universal nature of the problem, and the results of long periods of wakefulness having been shown to be akin to having a higher than permitted blood alcohol content, no solution which is both legal and effective seems to be available to people in aviation.

Discussing this with your AME usually leads to advice like "a bracing walk before you go to bed" (yeah right, have a stroll around the Greenspoint Mall in IAH, known to the locals as Gunpoint Mall :yuk: ), do not watch TV before attempting sleep and other such utterly useless cr@p.

You underperform when fatigued and you are damned because you didn't declare yourself unfit for flight.
You underperform with traces of a sedative in your blood and you will be hung out to dry as a junkie who disregarded the regs.
You refuse to fly because you are fatigued more than once every 5 years and you can be sure that your boss will want a word.

Yet anothe situation where online personnel is left to carry the can by the hypocrite bean counters and spineless regulators.
Endless money is spent on marketing the latest on-board entertainment system, precious little on improving sleep patterns for pilots and FAs.

[Northern Chique]

I know some workplaces have stringent drug and alcohol policies and I am one of the people that tests for and enforces drug and alcohol policy in my workplace.

Benzodiazapines is one of the listed prohibited agents and if caught, the person is immediately stood down, then the sample independantly tested, and if above cutoff, diciplinary action is taken. In one contracting company, their policy is immediate dismissal after definitive testing.

We also are introducing a fitness for work testing unit. This tests for fatigue rather than outright drugs and alcohol. This unit will give a much more accurate overview of the persons ability to conduct their job in a safe manner.

We have various programs in place to encourage fatigue management and if that means a chap or chapess taking the shift off, well so be it. Some folks just take a whole lot longer to recover from factors affecting their sleep patterns. Ive sent some off to their GP's who have recommended them to the sleep clinic in Sydney for further treatment and testing.

One startling result was the amount of possibly stress or environment related sleep apnoea being exposed.... food for thought...

[gingernut]

Discussing this with your AME usually leads to advice like "a bracing walk before you go to bed" (yeah right, have a stroll around the Greenspoint Mall in IAH, known to the locals as Gunpoint Mall ), do not watch TV before attempting sleep and other such utterly useless cr@p.

I can only sympathise, can't imagine the pressure your under, especially without a decent sleep, but in all seriousness, have you tried any non-drug measures ?

I always feel a little inadequate when I give this "common sense" advice out to my patients. Does exercise, camomile tea, relaxation techniques etc etc make any difference ?

[f40]

Gingernut, they do and they don't is the honest answer.
At home, camomille tea, relaxation techniques and exercise all work wonders. I know, because I have tried them all at one stage or other. After many years, I have come to the conclusion that for me personally a combination of sex, regular exercise and adapting my sleep pattern to home time ASAP is what makes jetlag suviveable.

But that's at home.
Now let's have a look at our life down route.
Only about 20% of hotel rooms abroad provide a water cooker. So to be able to make camomille tea, you need to carry a portable cooker in your suitcase. (plus a cup, tea bags, a spoon and sugar) It takes a lot of space, it's heavy and it breaks easily. Tried and discarded.
Sex is not really an option on a regular basis unless you fly with your other half.
Imagine trying relaxation techniques under the following circumstances. You have to sleep at odd hours, in hotels with cardboard walls, the maids chattering in the hallway, the elevator going PING every 5 minutes, the ice machine rattling out cubes, city traffic, honking horns and sirens wailing outside your windows while your mind is telling you "If you don't sleep now, you'll be utterly knackered during the flight".
You'd have to be a buddhist monk to benefit from relaxation techniques under those circumstances. :hmm:
The best I manage is try not to let my BP go through the roof and try and accept with equanimity the fact that once again I will have to fight my way through a night of changing time zones with my body temp regulation mechanism turned down by a confused bio-clock, trying desperately to stay awake.

The advice given by you and your well meaning colleagues is fine for normal people who live normal lives, but for us it lacks a certain ...ermm.... applicability. ;)

[gingernut]

sorry can only sympathise....but will carry on thinking.

[Loose rivets]

Despite painting a graphic picture, I don't want to send out the wrong message. Don't resort to medication unless you are really very seriously concerned about your failure to get adequate sleep.

Zolpidem seemed to allow me to rem-sleep*, which I seem to need more than most. Five early's in a row was my worst scenario, because I have always remmed between five and ten AM.

The problem is self-fueling. Going to bed concerned that you will not sleep, is a sure-fire way to not sleep. I'll be okay if I can get five hours, becomes four hours, then three. If only I can get a couple of hours. You know if you start the day like this, everything will turn to c**pp. It's not your fault, its Murphy's. The weather will be gruesome...and it can't be your fault that the galley has fused.

It has to be better to have some help. I'm not qualified to express an opinion about the type of drugs that are suitable for modern pilots; and I make the distinction with the new generations because of the differences in the neurological demands. Staring at a scanned and very bright CRT for instance, is quite different to the old days. Add to this, the average traffic while commuting, and you guys are in a different world to the one I started in.

For me, having an escape route in the form a tablet ‘at the ready', is the best way that I can avoid taking it. Just knowing it's there relaxes me.

*Now there is some new work on the difference between rem-sleep and recall-able dreams (Scientific American snippets that they send on AOL) it makes assessing your sleep quality even harder than before.