Clinical toxicological cases used in the Dutch Quality Assessment Scheme

Donald R.A. Uges, Ph.D., R.HP, clinical and forensic toxicologist - pharmacologist, Chairman of the KKGT

Daan Touw Ph.D., R.HP, clinical pharmacologist, Director of the KKGT.

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The Dutch Association for Quality Assessment in TDM and Clinical Toxicology (KKGT) organises different quality schemes such as for antimicrobial drugs, cardiac drugs, anti-HIV drugs, psychiatric drugs, drugs of abuse and clinical toxicological cases. Besides sending serum or urine sample(s) for just quantitative analysis and to compare the qualitative results with the true value (being the exact weighed pure compound in calf serum), the KKGT has additional quality assessment schemes with samples for both analysis and interpretation. One of these schemes is clinical toxicology. The participant gets a case report (usually real) with one tube with urine, serum or whole blood. The material is spiked with one or more drugs. Based on the anamnesis, they have to perform first a qualitative screening followed by quantitative determinations of the important substances. Participants also have to provide information for the clinician about the poisoning, the advised treatment, and the prognosis. Twice a year, the KKGT used to undertake a proficiency test in toxicology together with the UKNEQAS (John F.Wilson Ph.D. Cardiff UK). Unfortunately, the role of the hospital pharmacist in the Netherlands and of the clinical biochemist in the UK is not always the same with respect to clinical toxicology. Therefore, not all cases are useful for an international proficiency test.

The aims of the KKGT Dutch clinical toxicological proficiency tests are:

• quality assessment of the methods used (apparatus, extraction standards etc),
• quality assessment of the toxicological and therapeutic advice provided,
• to inform the participant about new or actual poisonings, about the good and bad analytical methods, to discuss the best possible treatment, and to warn for hazardous treatments.
  As requested, we publish some of the QA cases. We add the results of the participants, our discussion and the information we provided to the participants in the subsequent report. We hope that you can learn from our information and that these cases will be a subject of discussion in this bulletin. If you need more information or background about these (mostly) real cases, please do not hesitate to contact us.

KKGT-UKNEQAS TOXICOLOGY PROFICIENCY TEST November 2002

Participants were provided with a 5-ml sample of new-born calf serum and the case history printed below. They were asked to analyse the sample and then to advise about the optimal treatment of the patient, using a questionnaire provided.
Sample composition:
The sample was prepared from new-born calf serum gamma irradiated from Invitrogen, Life Technologies, Breda, The Netherlands. The sample was spiked by addition of the weighed-in concentration of 31.28 mg / L lamotrigine and 201.04 µg/L / L citalopram. Sodium azide (0.1%) was added as a preservative.

Case History
The case involves a woman, born December 1971, with a history of several suicidal attempts (acetaminophen, valproic acid) and automutilation. Since December last year, she has been prescribed tablets against hallucinations, borderline disorder (Cipramil® 40 mg/daily) and seizures.
She does not smoke nor drink alcohol. It is reported that she has taken 70 tablets between 1 12 hours before admittance into our hospital. She then called her friend, who found her drowsy and called the police. During admittance: EVM score 3-6-6; temperature 37.2 °C blood pressure 130/70 pupils isocoric; several small blue spots all over her legs. Blood chemistry: pH 7.44; pCO2 4.3 pO2 10.1; HCO3 22; saturation (without O2) 96%. ECG: no abnormalities; desperate, labile, theatric presentation. Sedated, emotional with borderline problems. Please screen the samples for toxicological involvement, measure relevant serum concentrations of poisons and give advice.
N.B. Due to shortage of supply, the principal metabolite of the drug concerned, is not available. However, its concentration is 25% of the parent component.

Comments By Donald R.A. Uges Ph.D., clinical and forensic toxicologist-pharmacologist, KKGT, Dr. John F. Wilson, Senior Lecturer in Pharmacology, UKNEQAS
This case was, like most KKGT cases, a real one. One litre of serum with 30 µg/L lamotrigine, 200 µg/L citalopram and 50 µg/L of desmethylcitalopram was needed to prepare samples. Unfortunately the metabolite of citalopram was not available in sufficient quantities.
Some participants found methanol. This was used as solvent during spiking the serum. The concentration of methanol was unrealistically high and did not fit with patient's clinical picture. In future cases, we will mention this on the sample label.
Some participants, especially the Dutch ones, told us that they normally receive more information than in these "test-tox cases". Luckily, we normally do so as well, but such additional case report information is not helpful to participants with their selection of appropriate qualitative and quantitative analyses.
In this case, the word 'epilepsy' was the key information. With the HPLC-DAD-library combination (STIP) or RP-HPLC, most participants found the toxic concentration of lamotrigine and the therapeutic level of citalopram.
Patient outcome: We heard subsequently that the patient had taken 70 tablets of lamotrigine. Her serum level was about 20 times higher than is considered therapeutic. She was treated with activated charcoal for gut decontamination and sodium sulphate as laxative. Her haemodynamic and pulmonary parameters were stable overnight. The next day she was sent home via the psychiatrist with 2mg of pimozide and 40 mg of citalopram once a day.
In accordance with the Poisindex®, several toxic effects could have been noticed: Seizures, ataxia, depression of the central nervous system, a coma of short duration, dyskinesia, slow cardiac conductivity, possible hypokalemia, nausea and dry mouth. We think that seizures would have been the most severe outcome. No toxic effects were noticed in this case. However, poisonings with such new, unknown compounds require a (short) admittance with monitoring of the patient.

KKGT-UKNEQAS TOXICOLOGY PROFICIENCY TEST A 2003
John F. Wilson Ph.D., Donald R.A. Uges, Ph.D.

Case History
A 23 year-old male is admitted to your hospital following a road traffic accident. Eyewitnesses reported that he had driven erratically, at high speed, often on the wrong side of the road, before crashing at a bend in the road. On arrival at the scene, the police found the lone car driver appeared physically unharmed but was disorientated, unsteady on his feet and had slurred speech. He was at times aggressive but lapsed into unconsciousness. On admission to hospital his physiological signs were unremarkable with blood pressure 126/78, pulse 54, miosis and a Glasgow Coma (EVM) Score of 3. After approximately 1 hour, he regained consciousness. The police found materials suspected to be illicit drugs in the car including 2 empty plastic screw-capped bottles labelled, amongst other things, with the initials GHB. . Please analyse the samples for possible toxicological involvement and advise on treatment.
Samples: A 7-ml blood sample was supplied prepared from packed red cells diluted with plasma (Welsh Blood Service) to give a normal concentration of haemoglobin. The sample was preserved by addition of 0.1% sodium fluoride. The blood was spiked by addition of 135.5 mg/L gamma hydroxybutyric acid (GHB, 4-hydroxybutyric acid, Fluka), 71 µg/L cocaine (Sigma-Aldrich), 62 µg/L ecgonine methylester (Sigma-Aldrich) and 155 µg/L benzoylecgonine (Sigma-Aldrich). In addition, a 20ml urine sample was prepared from drug-free urine preserved with 0.1% sodium fluoride. The urine was spiked with 2705 mg/L GHB, 4.0 mg/L ecgonine methylester and 5.0 mg/L benzoylecgonine. No cocaine was added to the urine.

Comments by D.R.A. Uges, Ph.D
The case was based on one in a series presented in a poster by A. Oestreich and P.X. Iten at TIAFT 2001 in Prague (See TIAFT proceedings page 387). The dominant finding is of high concentrations of GHB in blood and urine from GHB misuse immediately preceding the traffic accident. The concentrations of cocaine metabolites in blood and urine point to this being a less important, incidental finding in the overall clinical picture. The presence of metabolites from cannabis use in the blood products used to prepare the sample was an unexpected finding not mirrored in the preparation of the urine sample.
Participants were given information that GHB might be involved so that the data returned would survey the current availability and status of analyses for this topical compound. The quantitative data for GHB were continuously variable over a wide range both in blood and urine such that no data points were identified as greater than 3 standard deviations from the consensus mean. Forced omission of the six blood GHB measurements <75 and >225 mg/L and of eight urine measurements <1000 and > 4000 mg/L reduced coefficients of variation to 27.5 and 20.0% for the remaining 30 blood and 24 urine measurements, respectively.

• Effects occur 15-60 min after ingestion and usually resolve spontaneously within 24-48 hrs
• Consider activated charcoal in patients who present within 1 hour
• Monitor (bp, pulse, respiration) for at least 2 hours after overdose, longer if symptoms present
• Control convulsions with iv diazepam
• Bradycardia may respond to atropine
• Naloxone has been shown to reverse some effects of GHB in animals and might be considered as an alternative to ventilation for coma and/or respiratory depression
• Other measures as required by clinical condition

KKGT-UKNEQAS TOXICOLOGY PROFICIENCY TEST A 2002

The following case was based on an industrial accident where the identity of the chemical agent involved was known. The scenario was transferred to a domestic setting so as to add a component of investigation and identification rather than merely quantitation of the components.

Case History
A 58 year-old man is found collapsed inside a garden shed that he had been painting with wood preservative. There are no superficial signs of skin or mucosal burns. Please analyse the samples for possible toxicological involvement and advise on treatment.

Comment
The case was presented with inadequate supporting information as often reflects the case of acute admission of patients with unexpected coma. The case also reflects the expectations of some medical staff that the laboratory can perform miracles and provide useful information to support patient management with only a minimum of information provided.
The case simulated was of acute toxicity due to dermal absorption and/or inhalation of the commonly available wood preservative creosote, although only phenol and one cresol derivative were spiked into the samples provided. The concentrations were chosen to reflect cases of acute toxicity or possible fatality.
Blood: The 10 ml sample was prepared from packed red cells diluted with plasma and pH 7.5 HEPES buffer to give a normal concentration of haemoglobin. The sample was preserved by addition of gentamicin sulphate 0.1g/L and penicillin 0.1g/L. The blood was spiked by addition of 5.2 mg/L phenol (Sigma Chemical Co.) and 7.6 mg/L p-cresol (Sigma Chemical Co.).
Urine: The 20 ml sample was prepared from drug-free urine preserved with 0.1g/L sodium fluoride. It was spiked by addition of 50 mg/L phenol and 76.5 mg/L p-cresol. Green food colouring was added to give the urine a slight greenish tint.

Results
Reports were received from a total of 77 participants (28 UKNEQAS, 49 KKGT)
Quantitative data as mean ± standard deviation (number of measurements)
Blood phenol 1.7±1.8(n=2) mg/L Blood cresol 7.2±0.3(n=2) mg/L
Urine phenol 39±17(n=4) mg/L Urine cresol 61±16(n=2) mg/L
There were unexpected single reports for blood alcohol 118 mg/L, blood methanol 43 mg/L, urine methanol 59 mg/L, blood acetone 10 mg/L, blood trichloroethanol 133 mg/L, blood clonidine 20 µg/L and urine hippuric acid 431 mg/L.
Phenol is rapidly absorbed via the lungs and through the skin. Symptoms may develop within 5 to 30 minutes after exposure. Severe toxicity causes profound central nervous system depression with coma and respiratory arrest. TOXBASE (UK, National Poisons Information Service, www.spib.axl.co.uk) states that treatment for dermal exposure consists of rapid decontamination of the skin with copious amounts of water, maintenance of the airway if consciousness is impaired (with intubation and assisted ventilation being necessary if pulmonary oedema is present). Any metabolic acidosis will need to be corrected using sodium bicarbonate. Renal function should be monitored and failure treated conventionally.
It was thought that laboratories would perform and report on standard toxicological investigations for common drug classes, but those findings would be negative. This would lead to the requirement for the performance of further investigations of a more specialised nature for less common compounds, with some thought being given to the scenario presented. It should not be forgotten that the case was based on a real event and, although rare, such investigations may be necessary.
It was assumed that the interpretation would suggest that insufficient information or incomplete case details had been provided, and that a more definitive patient history and scene examination would be sought before further testing or interpretative comment. Those with access to chromatographic procedures might report the presence of unexpected hydrocarbon component(s) and hence possible toxicological involvement. Where facilities were not available for the identification or quantitation of the possible causative agent(s) involved in this case, it was assumed that referral with a specific request would be recommended in the report returned.

KKGT Toxicology PROFICIENCY Test B 2002

Case history
The patient (female, 45 years-old, 70 kg) was found this morning She was not approachable and beside her were four empty boxes of her own medication: Thyrax®, Zyprexa ®, Truxal®, promethazine and diazepam. ECG: sinus rhytme 91/min.; PR 140 ms;QRS 96 msec; QTC 506 ms, negative T V2 tot V6. Creatinine 83; pH 7.44; pCO2 5.2; pO2 10.9; Bicarbonate 26; BE 2.7; saturation 96%. NB. 0,1% Sodium azide was added as a preservative and ethanol was added as the vehicle for drug addition. In this case the ethanol concentration of the patient was zero.

Spiked Composition of serum:
Olanzapine 420.1 µg/L, chlorprothixene 440 µg/L, diazepam 411.5 µg/L, desmethyldiazepam (= nordazepam) 490.3 µg/L ( as antioxidant, ascorbic acid 1500 mg/L).

Comments by D.R.A. Uges, Ph.D.
This case concerns a patient who was brought to our hospital after a suicide attempt with various substances, among which was olanzapine. The patient already had an extended medical history. One of the empty boxes, that was found, had contained Thyrax®. Therefore, some of the participants thought they had to determine T3 and T4.
In our E.Q.A. tests, we always use exogenous substances added to calf or human serum. The determination of levothyroxine in this test case therefore is useless.
However, the clinical practice monitoring of T3/T4 is indicated, especially because symptoms of poisoning (tachycardia and tremor) are not always immediately evident.
Olanzapine poisonings occur regularly and several lethal cases are known.
The combination of tachycardia, low blood pressure, respiratory failure and in particular convulsions can be fatal, especially when discovery of the patient is delayed (t½ = 1.5 day!).
Since the induced combination of convulsions and cardiovascular problems can be life threatening, I always advise benzodiazepine (e.g. diazepam) protection under coronary care and sometimes artificial respiration. With this method, we have succeeded in treating patients with olanzapine poisoning whilst we measured levels far above those in lethal cases.
It may be obvious that lethal values are hard to compare, since the circumstances, the co-medication and the time of discovery of the patient can be dissimilar.
Furthermore, there is the problem of the instability of olanzapine in serum samples. It is not clear how the samples were treated in the described cases. Some articles have been published about the instability of olanzapine in calf serum (Ther. Drug Monit. 1999; 21: 86-90 and 2001; 23: 454-455) mostly by the same group of Australian authors. Their advice is to add to the sample 1.5 - 2.5 mg/ml ascorbic acid. We on the other hand sincerely doubt if olanzapine is as unstable as presumed.
The average of all the participating laboratories was 105 % so there is no dissociation worth mentioning after adding 1.5 mg ascorbic acid per ml calf serum. The amount of chlorprothixene was high/normal but toxicologically of no interest.

In conclusion
- Severe olanzapine intoxication, coronary care required.
- Activated charcoal might be useful (in the real case the patient was given activated charcoal)
- Diazepam and desmethyldiazepam are sufficiently anticonvulsive
- I would not prescribe prophylactic therapy against extrapyramidal effects
- Check O2 tension, pH and potassium (The patient's potassium level was somewhat disturbed but she did not show arrhythmia's).

KKGT Toxicology PROFICIENCY TEST B 2003

Case History
A 52 year- old woman may have taken her whole available amount of cardiac pills about one hour before admission. The neighbour accompanied her to the hospital.
According to the neighbour, she had on a previous occasion taken an overdose of paracetamol as suicidal attempt. In that case, she was treated with gastric lavage.
The patient is very confused, constantly crying and difficult to understand. The clinical picture is normal.
An electrocardiogram and clinical chemistry are not yet available.
Neither her pharmacist nor her general practitioner is available to provide information.
Because we have no free beds available, we want a toxicological screening as soon as possible and advice for prognosis and treatment.

Composition: digoxin: 12.82 µg/l

Comments by D.J. Touw, Ph.D. and D.R.A. Uges, Ph.D.
This is clearly a poisoning with digoxin. The serum concentration in a blood sample drawn 1 hour after ingestion was 12.8 g/l. The pharmacokinetics of digoxin can be described with a 2-compartment model with a distribution phase and an elimination phase. Maximum serum concentrations after oral administration are reached after 60-90 minutes. The initial volume of distribution is relatively small and the serum concentration is thus high. The possibility exists that the level will decline rapidly to less toxic values.

Clinical symptoms and treatment of a digoxin intoxication
After an acute intoxication, the most important signs are: bradycardia, (supra) ventricular extrasystole, (supra) ventricular tachycardia, bigeminy, ventricle fibrillation and AV-conduction disturbances. Hypotension may occur. Nausea, vomiting (sometimes anti-emetics are needed), diarrhoea, dizziness and hyperkalaemia are frequently seen. The hyperkalaemia is logical regarding the mechanism of action of digoxin and is the result of a displacement of intracellular potassium to the extracellular compartment (control electrolytes and osmolarity) In serious cases of digoxin intoxication, generalised convulsions may occur (Phenytoin is useful against ventricular arrhythmia and against seizures). Hypokalemia and hypomagnesia will increase digoxin toxicity (e.g. as result of diuretics).
After ingestion, absorption must be avoided by vomiting or gastric lavage within 1 hour after ingestion. Activated charcoal must be administered together with a laxative (Sodium sulphate). The patient should be transferred to an IC unit with maximal cardiac support. The pharmacy must consider ordering digoxin antibodies (Antidigoxin Fab Fragments) (very expensive and often not necessary).

Serum levels
When digoxin antibodies are not administered, a second blood sample, 6 hours after ingestion, should be drawn for digoxin analysis.
Digoxin is assayed usually by immuno-assay. The FPIA technique measures total digoxin concentration and the MEIA technique only the unbound concentration in the presence of Fab fragments. When it is decided to administer digoxin antibodies, the FPIA technique will thus result in very high digoxin levels, in contrast to the MEIA technique. It is very important to know the pro's and cons of your own digoxin assay!

The present patient
The patient was admitted to the hospital as presented in the case history. Despite the high digoxin level on presentation, she was remarkably well. She was not treated with digoxin antibodies. A second sample drawn 6 hours after ingestion showed a much lower digoxin level. The patient recovered well and left the hospital in a good condition.

KKGT Toxicology PROFICIENCY test C 2002

Case history
A 2 year-old girl of 12.6 kg may have taken 28 tablets from her teenage mother who was sleeping. The mother takes these tablets when she is travelling. The mother panics. The child looks clinically normal, without any sign of a poisoning. Please be so kind to determine if she really took mother's tablets and if so, which ones and how much. What may be the prognosis and the right treatment?
Spiked composition: cyclizine 923 µg/l.

Comments by D.R.A. Uges, Ph.D.
The girl took about 28 tablets of 50 mg cyclizine. The time of intake of the tablets was not known, as the mother was sleeping. She had to wake, then discover that the tablets were taken, call the general practitioner, find somebody to take care of the other two children and finally to go by taxi to the hospital. On admission (some hours later) the child was lively, clear and active. No medical abnormality was noticed. The possible intake was 1400 mg of cyclizine. That may cause seizures, shock, hypertensive crisis, tachycardia or bradycardia, hypothermia and hallucination. The serum level of cyclizine on admission was 800 µg/l (in the test 923), one day later 500 µg/l and the second day not detectable. No sign of a poisoning was noticed during the two days in hospital. The situation at home had to be controlled before the girl was sent home.
Discussion: We had no pure norcyclizine, therefore this metabolite couldn't be measured in the real case and not in this test.
It is difficult to estimate how many tablets the girl really had taken, as the time of intake was not known and cyclizine serum concentrations decrease quickly during the first hour.
The number of 28 tablets seems too high. Baselt (Disposition of Toxic Drugs and Chemicals in Man) mentioned a case of a 2-year-old girl, taken 800 mg cyclizine as tablets. She developed severe seizures 4 hrs after admission in the hospital and died.
Treatment: We would never advise stomach lavage to a 2 year-old girl without symptoms. Furthermore, stomach lavage is only useful within the first hour after ingestion, which is not the case here. Activated charcoal may be useful. I am inclined to give diazepam rectally as rectiole (small rectal solution).
Analysis: With HPLC-DAD-Library most participants found Cyclizine at the right serum concentration. To exclude paracetamol (acetaminophen) and salicylates by a suitable method makes sense in this case. On the contrary, to screen for alcohol in an active 2 year-old girl is useless.
One participant asked for urine as matrix for screening. Our program is based on serum analysis with pharmacokinetic calculations and advice. Cyclizine is hardly excreted unchanged in urine and norcyclizine was not available.