Abnormal behaviour symptoms and conditions

Researchers have been doing studies for many years regarding trying to determine the role of genetic factors in patients response to Singulair (Montelukast).

This study from Spain identified the following gene variations hypothesize to be related to leukotriene pathway response. Sixty one patients with asthma were studied. Three gene types were identified:

type 1. Thirty-two patients (52.5%) were homozygous for the five repeats allele;
type 2. 17 (27.9%) were heterozygous (4/5 repeats)
type 3. 12 (19.7%) were homozygous for 4/4 repeats.

The study showed that montelukast was effective for types 1 and 2 but not effective for type 3. Type 3 represented approximately 20% of the group study.

"After the montelukast treatment decrease number of asthma exacerbations, improvement of FEV(1) and decreased use of beta(2) agonists was observed in patients with 5/5 or 4/5 repeats. Conversely, the patients with 4/4 repeats genotype did not modify these data after treatment."

So it seems logical that if it can be identified that montelukast is not effective for certain gene type variations, then montelukast could cause adverse side effects in certain gene type variations.

It is interesting that 20% of this group does not respond positively to montelukast. That is the exact same number that even Merck says gets a headache from montelukast. Headache is the highest incidence of adverse side effects that has been reported. That comparison, however, is just a coincidence because it has not been studied and proven. Maybe.

Where are the studies that pertain to gene type variations and adverse side effects? You would think that somebody could do them.

Respir Med. 2008 Jun;102(6):857-61. Epub 2008 Mar 12. Links
ALOX5 promoter genotype and response to montelukast in moderate persistent asthma.Telleria JJ, Blanco-Quiros A, Varillas D, Armentia A, Fernandez-Carvajal I, Jesus Alonso M, Diez I.
Institute of Biology and Molecular Genetics (IBGM/CSIC), University of Valladolid, Valladolid, Spain. ******

BACKGROUND: It was hypothesized that asthmatic patients with mutant alleles in the leukotriene pathway should not respond to leukotriene receptor antagonists and the concept of a tailored treatment is increasingly supported. METHODS: Sixty-one patients (mean age 24.9 years, range 14-52) with moderate persistent asthma were clinical and immunological assess prior and after a 6-month treatment with montelukast. Tandem repeat polymorphisms were genotyped in the promoter (-147 to -176) of 5-lipoxygenase gene (ALOX5). RESULTS: Thirty-two patients (52.5%) were homozygous for the five repeats allele; 17 (27.9%) were heterozygous (4/5 repeats) and 12 (19.7%) were homozygous for 4/4 repeats. After the montelukast treatment decrease number of asthma exacerbations, improvement of FEV(1) and decreased use of beta(2) agonists was observed in patients with 5/5 or 4/5 repeats. Conversely, the patients with 4/4 repeats genotype did not modify these data after treatment. CONCLUSIONS: It was confirmed that ALOX5 promoter polymorphisms have a clear influence in montelukast response in atopic moderate persistent asthma patients. The genetic study could identify those patients most likely to respond to montelukast.

PMID: 18339529

Below is the latest ADR report on Singulair from the United Kingdom. I deleted side effects reports by very small numbers of patients in order to keep the post briefer. This shows the total number of reports since Singulair was approved in the UK.

I don't know the total number of prescriptions for Singulair in the UK. It is considered expensive.

Drug Analysis Print
Drug name: MONTELUKAST
Drug name: MONTELUKAST Report type: Spontaneous
Report run date: 13-May-2008 Report origin: UNITED KINGDOM
Data lock date: 09-May-2008 08:00:02 PM Route of admin: ALL
Period covered: 01-Jul-1963 to 09-May-2008 Reporter type: ALL
Earliest reaction date: 01-Jan-1997 Reaction: ALL

Cardiac disorders-TOTAL 64
Palpitations 29
Myocardial infarction 6
Tachycardia 6
Diarrhoea 84
Dyspepsia 24
Abdominal pain 98
Abdominal pain upper 22
Nausea 84
Vomiting 52
Dry mouth 15
Asthenia 13
Fatigue 45
Malaise 32
Sudden death 1
Pyrexia 10
Chest discomfort 12
Feeling abnormal 16
Influenza like illness 17
Irritability 18
Drug interaction 13
Chest pain 13
Arthralgia 59
Myalgia 38
Muscle spasms 24
Pain in extremity 14
Balance disorder 10
Lethargy 16
Somnolence 23
Psychomotor hyperactivity 25
Headache 221
Dizziness 68
Neuropathy peripheral 7
Convulsion 6
Epilepsy 7
Dysgeusia 7
Hypoaesthesia 6
Tremor 18
Nervous system disorders TOTAL 526
Abnormal behaviour 13
Agitation 12
Anxiety 18
Aggression 30
Depression 23
Insomnia 58
Abnormal dreams 12
Nightmare 49
Hallucination 21
Sleep disorder 15
Psychiatric disorders TOTAL 364
Asthma 36
Allergic granulomatous angiitis 43
Angioedema 12
Swelling face 12
Erythema 13
Pruritus 32
Rash pruritic 17
Rash 55
Urticaria 33

TOTAL NUMBER OF REACTIONS 2841
TOTAL NUMBER OF FATAL ADR REPORTS* 19
TOTAL NUMBER OF ADR REPORTS* 1489