Medikinet® 20 mg: composition and pharmaceutical form
One tablet contains 5 mg, 10 mg or 20 mg of methylphenidate hydrochloride, which corresponds to 4.32 mg, 8.65 mg and 17.30 mg of methylphenidate.
The tablets are swallowed whole with a little liquid, during a meal or right after it. The influence of food on the absorption of methylphenidate from the tablets has not been studied, but it cannot be ruled out, so the medicine is taken in a standardised way: every day at the same time relative to meals.
How Medikinet® 20 mg works
The medicine mildly stimulates the central nervous system, and its influence on the psyche is more noticeable than on motor activity. The exact mechanism in humans is not fully understood; the action is assumed to be linked to cortical stimulation and, probably, to excitation of the activating reticular formation. Methylphenidate is thought to block the reuptake of noradrenaline and dopamine into the presynaptic neuron and to increase the release of monoamines into the extracellular space.
The medicine is a racemic mixture of the d- and l-threo enantiomers, with the d form pharmacologically more active. Methylphenidate is absorbed quickly and almost completely, but because of a marked first-pass effect its absolute bioavailability is low — about 30%. Taking it with food speeds up absorption without changing the total amount absorbed. The maximum plasma concentration is reached on average 1–2 hours after taking 10 mg, and a relatively short half-life corresponds to the duration of action, which is 1 to 4 hours.
Indications
The medicine is indicated as part of a comprehensive treatment programme for attention deficit hyperactivity disorder in children from 6 years, when other measures have proved insufficient. Treatment is started under the supervision of a doctor specialising in behavioural disorders in children.
The diagnosis must meet the current DSM criteria or the ICD-10 recommendations and rest on a full history and assessment of the condition, not on the presence of one or several symptoms. The specific cause of the disorder is unknown and there is no single diagnostic test, so medical, psychological, educational and social criteria are used. The comprehensive programme includes psychological, educational and social measures alongside drug therapy; methylphenidate is not indicated for every child with this diagnosis, and the decision is taken after a thorough assessment of the severity and persistence of the symptoms with the child's age in mind. If the symptoms are linked to an acute reaction to stress, methylphenidate is usually not indicated.
Method of use and dosage
Before prescribing, a baseline assessment of the circulatory system with measurement of blood pressure and pulse is mandatory. The history includes the medicines being taken, past and current physical and mental disorders, cases of sudden cardiac or unexplained death in the family, and exact measurements of height and weight before treatment starts.
| Situation | Scheme |
|---|---|
| Starting dose | 5 mg 1–2 times a day, for example at breakfast and lunch |
| Raising the dose | if needed, weekly by 5–10 mg a day, guided by tolerance and effect |
| Goal of the adjustment | satisfactory symptom control at the lowest possible daily dose |
| Timing of the dose | so that the peak of action falls on school and social situations |
| Last dose of the day | no later than 4 hours before sleep, otherwise difficulty falling asleep is possible |
| Children under 6 | not used: there are no data on efficacy and safety |
During treatment, growth, mental state and the state of the circulation are monitored continuously. Blood pressure and pulse are plotted on a centile chart after every dose change and thereafter at least once every 6 months; height, weight and appetite are recorded at least once every six months and checked against the growth curve. The appearance of new mental disturbances or the worsening of previous ones is assessed after every dose adjustment, then every 6 months and at every visit. Separately, the risk of faking the dose, of misuse and of abuse of the medicine is monitored.
Contraindications
The list is broad and covers the psyche, the heart and the thyroid gland.
- hypersensitivity to methylphenidate or to any excipient;
- marked anxiety, tension or agitation — the medicine may intensify them;
- glaucoma, hyperthyroidism, thyrotoxicosis;
- severe angina pectoris, arrhythmia, severe arterial hypertension, heart failure, previous myocardial infarction;
- current severe depression, psychotic symptoms, a psychopathic personality structure, aggression in the history or suicidal tendencies;
- established drug dependence or alcoholism;
- use of non-selective irreversible MAO inhibitors now or in the preceding 14 days — risk of hypertensive crisis and hyperthermia;
- motor tics, tics in siblings, Tourette's syndrome in the patient or in the family history, and also pregnancy.
Special warnings and precautions
Methylphenidate is not used to treat severe depression — neither exogenous nor endogenous — and is not used to prevent or treat ordinary tiredness. Clinical experience shows that in children with psychotic disorders the medicine can intensify behavioural and thought disturbances, and that in severe depression and with suicidal thoughts it demands particular caution because of the risk of worsening the symptoms.
Growth, blood pressure and tics
- with prolonged use of stimulants in children, reduced weight gain and slowed growth were noted, so growth parameters are monitored carefully;
- if growth and weight gain fall behind what is expected, the medicine is stopped temporarily;
- blood pressure is monitored in all patients, and especially in people with hypertension;
- an increase in motor and vocal tics and in Tourette's syndrome has been reported, so before prescribing a stimulant a clinical assessment of tics is carried out;
- because of the possible reduction in appetite, caution is needed in anorexia nervosa;
- caution is also required in emotionally unstable patients;
- alcohol is excluded during treatment: it intensifies the undesirable effects of psychoactive agents on the nervous system;
- on the day of planned surgery the medicine is not taken, because of the risk of a sharp rise in blood pressure with halogenated anaesthetics.
Dependence and abuse
The available clinical data indicate that treatment with methylphenidate in childhood does not raise the likelihood of dependence later on, though this needs monitoring in each individual case. Prolonged abuse of the medicine leads to marked tolerance and psychological dependence with behavioural disturbances of varying degree, and with abuse by the parenteral route genuine psychotic episodes are possible.
Drug interactions
Because of the risk of hypertensive crises, the medicine is contraindicated in patients receiving non-selective irreversible MAO inhibitors now or in the last 2 weeks. With agents that constrict the vessels and raise blood pressure it is used with caution. How methylphenidate influences the plasma concentrations of other medicines is unknown, so caution is needed with medicines of narrow therapeutic range.
Case descriptions indicate that methylphenidate can inhibit the metabolism of coumarin anticoagulants, of anticonvulsants — phenobarbital, phenytoin, primidone — and of some antidepressants, tricyclics and serotonin reuptake inhibitors. With concomitant use their doses may need reducing and, at the start and on withdrawal of methylphenidate, plasma concentrations or clotting parameters for coumarins should be monitored. Serious adverse events, including cases of sudden death, have been reported with the combination with clonidine, although a causal relationship has not been established; the safety of the combination with clonidine and other central α2 receptor antagonists has not been systematically evaluated. Possible interactions with antipsychotics — haloperidol and thioridazine — have also been noted, and methylphenidate can weaken the hypotensive action of guanethidine.
Pregnancy and breastfeeding
Data on the use of methylphenidate in pregnancy are scarce, and animal studies showed a toxic effect on reproductive capacity. The potential risk to humans is unknown, and use during pregnancy is contraindicated.
Whether methylphenidate and its metabolites pass into breast milk is unknown. For safety reasons, when deciding whether to stop breastfeeding or the medicine, the importance of the treatment for the woman herself is taken into account.
Adverse effects
Very often, at the start of treatment, nervousness and insomnia appear — as a rule they can be reduced by lowering the dose. Reduced appetite is also common but usually transient.
- very common: insomnia, nervousness;
- common in the psychic sphere: unusual behaviour, aggression, agitation, loss of appetite, restlessness, depression, irritability;
- common in the nervous system: dizziness, drowsiness, dyskinesia, headache, excessive activity;
- common in the heart and metabolism: arrhythmia, palpitations, tachycardia, changes in blood pressure and pulse rate, usually upwards, reduced weight gain with prolonged use in children;
- common, other: abdominal pain, nausea and vomiting — more often at the start of treatment, eased by taking it with food — dry mouth, joint pain, hair loss, itching, rash, urticaria, fever;
- rare: angina pectoris, disturbances of accommodation and vision, delayed development with prolonged use in children;
- very rare: anaemia, leucopenia, thrombocytopenia, thrombocytopenic purpura, cardiac arrest, sudden death, seizures, choreoathetoid movements, impaired liver function up to hepatic coma;
- very rare in the psychic sphere and the skin: hallucinations, psychotic disorders, suicidal behaviour including completed suicide, the appearance or intensification of tics, Tourette's syndrome, erythema multiforme, exfoliative dermatitis, fixed drug eruption.
Very rarely, poorly documented reports of neuroleptic malignant syndrome were received; most of those patients were also receiving other medicines, so the role of methylphenidate remains unclear.
Overdose
Acute overdose is linked mainly to excessive stimulation of the central and sympathetic nervous system. Vomiting, agitation, tremor, hyperreflexia, muscle twitching, seizures followed by coma, euphoria, confusion, hallucinations, delusions, profuse sweating, flushing, headache, very high fever, tachycardia, palpitations, rhythm disturbances, raised blood pressure, pupil dilation and dry mucous membranes are possible.
There is no specific antidote. Treatment is supportive: the patient is protected from self-injury and from external stimuli that would intensify the overexcitation. If the symptoms are not too severe and the patient is conscious, emptying the stomach contents by inducing vomiting or by lavage is considered; in severe poisoning a carefully chosen dose of a short-acting barbiturate is given before lavage. Intensive care may be needed to support circulation and breathing and, with a very high fever, external cooling. The efficacy of peritoneal dialysis and haemodialysis in methylphenidate overdose has not been determined.
How to get a prescription for Medikinet® 20 mg online
Medikinet® 20 mg is a prescription-only medicine and belongs to the strictly controlled group: it is prescribed by a specialist in behavioural disorders in children, and a cardiovascular assessment is needed before treatment starts. During the online consultation the doctor will go through the diagnosis, the family history and the medicines being taken.
If the medicine is indicated, the doctor will issue an electronic prescription, set the starting dose and the size of each increase and explain which parameters to monitor during treatment and when to contact a doctor immediately.
