Drugs in Aviation

Drugs in Aviation
by
Wg Cdr PS Singh
Cl Spl (Med)
IAM, IAF

INTRODUCTION
Aircrew, like all of us, are prone to illness, but those who undertake self-medication, not only endanger their lives but also jeopardize the safety of costly aircraft.

The greater understanding of the central effects of drugs in humans and advances in drug development have now made possible the use of various drugs amongst the aircrew. In this context assessment of adverse effect, which a drug may have on the performance, has become an important part of its clinical profile and provides increased and more informed availability on potential therapy in aircrew.

The aim of the subject is to provide an understanding of the issues involved rather than to provide recommendations for drug use and to outline the various approaches that can be adopted to assess whether a drug can be used safely

SELF MEDICATION
Self-medication is one of the curses of modern civilization. The reason for doctoring one's own self can be many :

Knowledge of uses of common drugs: Increased knowledge of uses of common drugs through various media eg. Newspapers, magazines television, radio and cinema etc.
Easy availability of drugs: Most of the medicines are sold in the open market without a doctor's prescription. People can purchase these and stock at home for use in common illness and ailments without consulting a doctor.
Lack of education: There is lack of knowledge amongst aircrew regarding hazards of self-medication
Costlier medical treatment: There is no doubt that specialization and super specialization of various branches of medicine have resulted in increased cost of treatment. An average citizen cannot afford the best treatment with limited resources. General practitioners often do not satisfy the patients. The business oriented clinics and laboratories drain a lot of money for even minor cases of illness. Overcrowding of hospitals and charitable institutions also dissuade the common man to attend unless he is seriously ill and has no other way of getting treatment
Fear amongst aircrew from AMA : Aircrews are conscious of the fact that reporting to AMA for minor illness may result in stoppage of flying. This consciousness may become a phobia or fear complex so that they remain away from AMA for anything concerning their health. They reason to self-medication or report to unauthorized medical attendants or semi doctors/quacks for treatment and often get away with it.

Dangers of Self Medication
The dangers of self-medication are many as compared to the false belief of loss of flying category. These can be summarized as follows :

The symptoms may be precursor of a serious illness that will lead to physical harm once left undiagnosed and untreated adequately. Sometimes temporary relief of symptoms like headache, throat pain, coughs, fever etc. by self-medication may lead to false security and relief.
The drugs taken by an individual without a doctor's prescription may be wrong, insufficient or ineffective. Thus wastage of money and valuable time in the initial stage of illness results because of self-medication.
Over dosage of a drug may produce side effects or toxicity resulting in fresh problems for the self-medicator.
Aircrew undertaking flying after self-medication will endanger himself in flight because of aggravation of symptoms of illness and worsening the side affects of drugs

The modern aircrew has to remain fit physically and mentally to handle sophisticated high-speed aircrafts that demand split second decisions to avert mishaps or accidents. Any illness, however minor, will impair this alertness and quick decision making, The illness may get worse under flying conditions where hypoxia, + Gz acceleration, hypobarism and other flying stresses are constant factors of disturbance. If drugs are taken before flying, their unstated side-affects and toxicities will get aggravated in the flying environment and add to the hazard of pre-existing illness. The combined effects may cause accidents resulting in loss of life or aircraft or both entailing a severe loss to state.

ROLE OF AMA/SQUADRON MEDICAL OFFICER
The role of AMA is very significant in preventing the aircrew to fly under the influence of drugs. The medical officer, as a friend and colleague of the aircrew should explain them the dangers of self-medication. Lectures must be delivered at regular intervals to aircrew about hazards of drugs and medication in aviation. The squadron medical officer must create a belief in the aircrew that he is genuinely interested in health and flying fitness and not in lowering their medical category or stopping them flying. He should periodically examine the aircrew to evaluate their physical fitness. The preflight check up in the squadrons should be taken seriously

Civil Aviation Department - Board Of Trade
The civil aviation department - board of trade recommended that three questions a pilot should ask himself before flying if he is taking any medicine

Am I really fit to fly?

Do I really need to take any medication at all?

Have I taken this particular medication as a personal trial on ground at least. 24 hours before flight, to ensure that it will not have any adverse effects whatsoever, on my ability to fly?

Often the nature of illness for which treatment is being given will preclude flying .It is probably not practical to say that aircrew should not under any circumstances take any medication, but general principle is that no flying should be permitted during treatment with potentially hazardous drugs.

UNWANTED DRUG EFFECTS
It is helpful to consider unwanted drug effects under the following headings :

Predictable side effects : Unwanted pharmacological effects are likely to arise when normal doses are given e.g. Blurring of vision and dryness of mouth when anticholinergic drugs e.g. Stelabid are given for indigestion.

Overdose : Unwanted results from exaggeration of drug's desired pharmacological effect e.g. excessive drowsiness from tranquillizers, antidepressants and hypnotics.

Hypersensitive reaction : Specific allergic sensitivity to the drugs in question e.g. penicillin causes hypersensitive reaction. These range from mild reaction in the form of fever and rash to severe reaction leading to asthma and circulatory collapse.

Toxic effects and individual idiosyncrasy : Undesired results of drug administration in normal doses that may occur in some and not in others e.g. haemocytopaenia from chloramphenicol and jaundice from chlorpromazine (largactil) etc

Drug combination effects : Potentiation of a drug by another e.g. hypokalaemia from Thiazide and loop diuretics increasing digitalis effects and alcohol increasing the effects of various sedatives.

Inadequate elimination : Drug effect may be increased following normal doses where the means of elimination of that drug is inadequate, e.g. failure of detoxification in liver disease and of excretion in renal disease.

Generally speaking, it is not possible to lay down hard and fast rules about drugs and flying as to do so would lead to many anomalies. However, certain clear cut principles must be recognized and these are that any drug or drug combination which may significantly impair judgment and performance and any drug or drug combination which may lead to sudden, serious and possibly catastrophic consequences are incompatible with any form of aircrew duties

COMMON DRUGS

Antihistamines : These are one of the common drugs used very frequently either alone or in combination for treatment of motion sickness, URTI, hay fever and various other allergies. In view of drowsiness associated, flying is not permitted while taking antihistamines and thereafter for 24hrs. to 48hrs. Safer antihistamines that cause less sedation and side effects are Astemizole, Loratidine and Fexofenadine

Hypnotics : No aircrew should be permitted to carry out their duties while under the effect of any sedativc or hypnotic. It adversely affects the performance on the following day also and there is increased tendency to sleep. A hypnotic with short duration action and free of residual effects on performance at the commencement of next duty period can be used on individual merit of the case. The drug recommended by the Royal Air Force is Temazipam (10-20mg) at bedtime to induce sleep 12hrs before next sortie. It is effective in inducing sleeping and free from residual sequelae.

Tranquilizers, Antidepressants and psychotrophic drugs are not compatible with flying. Usually the reasons for which these are given will render aircrew duties inadvisable

Nasal decongestants : These usually contain antihistamines and sympathomemitic agents. If given occasionally as drops or spray, these are usually safe when given in normal recommended manner on individual merit of case when off flying for few hours. When given orally the side effects are such as to make aircrew duties unsafe and no flying is permitted within 48hrs of the last dose.

Analgesics : Analgesics like Aspirin, Paracetamol and Brufen are frequently used for minor complaints like headache, bodyache and feverishness. Gastric irritation, nausea and vomiting may result due to use of these drugs. Aircrew requiring these drugs must be thoroughly evaluated to rule out systemic illness e.g. hypertension, impaired visual acuity and sinusitis etc.

Antibiotics : Illness(Infection) for which antibiotic is prescribed, precludes from flying.However, in certain chronic benign conditions e.g Acne where longterm small dose antibiotic e.g Teramycin / Ledermycin / Doxycycline is being given without any side effects, may be permitted flying on individual merit of the case

Antihypertensive : If hypertension is controlled without any evidence of target organ involvement; the drugs like Atenolol (max up to 100 mg per day), diuretics e.g Dytide, Natrilix except Lasix (loop diuretic), ACE inhibitors e.g Enalapril (max up to 20 mg per day) and calcium channel blockers e.g Amlodepine (max up to 10 mg per day), either alone or in combination of any above two groups are permitted for flying after initial trial on ground level

Antiplatelet in IHD : Disprin in small dose for long-term prevention in CAD is permitted after initial trial without side effects in stable cases of IHD.which are asymptomatic without clinical or significant investigative abnormality.

Drugs in dyspepsia : Drugs used are antacids and H2 receptor antagonist. Simple antacids without anticolinergic action after trial on ground level without side effects may be permitted till ailment itself does not preclude from flying. Simlarly H2 antagonist for example Ranitidine in dose of 150-300mg and Omeprazole 20-40mg per day may be permitted for flying on individual merit of case if disease does not disqualify flying and enough trial on ground has been given without side effects.

Oral hypoglycemic agent and Insulin in DM : These disqualify flying except two drugs e.g. Metformin and Acarbose that have been observed in non-flying category without side effects e.g. hypoglycaemia and diabetes is controlled well without any evidence of target organ involvement

Steroids : The need to take steroids systematically would rule out flying duties. Steroids applied topically are safe.

Antimalarials : The customary antimalarial for prophylaxis e.g. Chloroquine, Pyrimethamine and Amodiaquine are safe for aircrew, preferably at weekends when off flying. Quinine should not be used in view of the danger of vertigo.

Antidiarrhoea Medication : Diarrhoea itself limits flying duty. Simple Kaolin is safe. Other antidiarrhhoeal agent has one or the other side effects. From all points of view, it is always safe to ground the aircrew with diarrhoea that cannot be controlled by simple measures without side effects.

Motion sickness : The drug required to control it, usually contains Belladona alone or antihistamines and because of their side effects one is not permitted for solo flying. These drugs are usually only permitted for limited periods to flying personnels during training.

Allopurinol in gout : This drug has very few side effects and a gouty subject well controlled on this could be fit for aircrew duties.after initial trial on ground level on individual merit of the case

Immunisation : Following usual vaccination procedures for cholera, influenza, typhoid, tetanus, rabies and hepatitis etc a minimum of 24hrs off flying is advocated.

Anaesthetics : After a local anaesthesia there should be a period of rest of one day of flying depending upon circumstances.

CONCLUSION
Ideally an aircrew on duty should take no medication. When any is prescribed, it should only be under close supervision of a doctor familiar with the problems of aviation and possible effects of what he is prescribing. Self-medication by aircrew should be discouraged.

REFERENCES :

Aeronautical Information Circular(1974). Civil Aviation Authority, United Kingdom, 14/1974

Amendment No. 24 and 25 on Hypertension and I.H.D, I.A.P 4303 2nd edition, 1998

Baird, J A; Coles, P.K.L and Nicholson, A.N. Human factors and air operations in the South Atlantic campaign

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