narcolepsy and its management

1. NARCOLEPSY

2. WHAT IS NARCOLEPSY…!?
• Narcolepsy is a chronic sleep disorder that causes drowsiness and frequent nap attacks during the
day.
• The name Narcolepsy comes from the French word, Narcolepsie, which is a combination of the
Greek word narke (numbness) and leptos (seizure).
• Four characteristic symptoms differentiate narcolepsy from other sleep disorders and are known as
the narcolepsy tetrad: sleep attacks, cataplexy, hypnagogic hallucinations, and sleep paralysis.
Cataplexy, a sudden bilateral loss of muscle tone of varying severity and duration without the loss of
consciousness
• Causes of narcolepsy: it is a nervous system disorder, which may be caused by a decrease in the
amount of hypocretin which is also called as orexin which is involved in controlling the appetite and
sleep patterns. The decrease in neurons containing hypocretin orexin may be due to an autoimmune
process, responsible for destruction of the hypocretin producing cells. There can be a genetic
component, as 3% of patients have a first-degree relative with the disorder.

3. SYMPTOMS OF NARCOLEPSY..
1) Cataplexy : a sudden bilateral loss of muscle tone of varying severity and duration without
the loss of consciousness. Patients can suffer from severe weakness, such as knee collapsing
to the ground. Cataplexy is often precipitated by situations characterized by high emotion
(e.g., laughter, anger, excitement). Cataleptic episodes can be brief, lasting seconds or can last
for several minutes.
2) Sleep paralysis : an episodic loss of voluntary muscle tone that occurs when the individual is
falling asleep or waking. Individuals are conscious but not able to move or speak.
3) Hallucination : while falling asleep (i.e., hypnagogic) and on awakening (i.e., hypnopompic)
are brief, dream-like experiences that intrude into wakefulness.

4. DIAGNOSIS OF NARCOLEPSY..
• Two tests are commonly used to diagnose narcolepsy, one is Polysomnogram and the other is
multiple sleep latency test.
i. Polysomnogram : it involves continuous recording of brain waves as well as nerve and muscle
function during sleep at night.
ii. MSLT : it measures how quickly a person falls asleep in a quiet environment during day time.
The patient takes four to five naps in a day, and narcolepsy is diagnosed if the patient falls asleep
quickly (within less than 5 minutes) and goes into REM sleep in two of those nap periods.

5. TREATMENT OF NARCOLEPSY..
• Non pharmacological methods : counselling the patients family regarding the illness,
to alleviate misconception around the individuals behaviour. Good sleep hygiene
should be encouraged. Daytime naps lasting 15 minutes can help the patient to stay
refreshed for several hours.
• Pharmacologic management of narcolepsy is focused on two primary areas: treatment
of excessive daytime sleepiness (EDS) and cataplexy.Sl.no Generic name Trade Name Daily Dosage Range (mg)
1. Dextroamphetamine Dexedrine 5-60
2. Methamphetamine Desoxyn 5-15
3. Methylphenidate Ritalin 30-80
4. Modafinil Provigil 200-400
5. Sodium oxybate Xyrem 4.5-9 grams per night.

6. MECHANISM AND ADR
1. Dextroamphetamine: they stimulates the release of noradrenaline, dopamine, and serotonin
and inhibits reuptake of amines by dopamine transporter and hence wakefulness may be
promoted. ADR include anorexia, xerostomia, insomnia, irritability, nervousness, drug
dependence etc.
2. Methamphetamine : it is a sympathomimetic amine which stimulates CNS activity. ADR
include Hypertension, increased heart rate, CVA, drug abuse etc.
3. Methylphenidate : it is a CNS stimulant which acts on the brain stem and cortex and blocks
the reuptake of norepinephrine and dopamine into the presynaptic neuron. ADR include
erythema, weight decreased, decreased appetite, headache, insomnia, nasal congestion etc.
4. Modafinil : they promotes wakefulness by binding to the dopamine transporter and inhibits
dopamine reuptake. ADR include rash, nausea, dizziness, anxiety etc.
5. Sodium oxybate : it is a CNS depressant with anti cataplectic activity in patients with
narcolepsy, in which the effect is mediated through GABA B action at the noradrenergic,
dopaminergic, and thalamocortical neurons.

7. ADJUNCT AGENT FOR CATAPLEXY:
• Fluoxetine : they increases brain level of serotonin and reduce cataplexy. ADR includes
diarrhea, indigestion, xerostomia, asthenia, dizziness, anxiety, pharyngitis etc.
• Imipramine : it belongs to the dibenzazepines group of compounds which blocks the uptake of
norepinephrine at the nerve ending. ADR include weight gain, bloating symptoms, xerostomia,
blurred vision, fatigue.
• Protriptyline : it is a tricyclic antidepressant which act by CNS stimulation. ADR include
hypotension, tachycardia, constipation, xerostomia, dizziness, blurred vision.
• Selegiline : it is an irreversible MOA-I and alleviates both narcolepsy and cataplexy. ADR
includes diarrhea, indigestion, xerostomia, headache, insomnia etc.