Protradon

Treatment of moderate to severe pain.

Posology

The dose should be adjusted to the intensity of the pain and the sensitivity of the individual patient. The lowest effective dose for analgesia should generally be selected.

Unless otherwise prescribed, Protradon drops should be administered as follows:

Adults and adolescents above the age of 12 years:

The usual daily dose is 50 to 100 mg (20 to 40 drops), 3 to 4 times a day. In children from 12 to 14 years, it is recommended to use the lowest dose.

For acute pain an initial dose of 100 mg is usually necessary. In case Protradon Drops is used for acute pain, it should be stressed that its activity is somewhat delayed in comparison to that of other analgesics.

For pain associated with chronic conditions an initial dose of 50 mg is advised. It is recommended, when possible in case of chronic treatment, to slowly increase Protradon dosage to its final recommended dose (with increments every 2 to 3 days) in order to reduce the incidence of adverse events.

Paediatric population:

Protradon drops is not suitable for children below the age of 12 years.

Geriatric patients:

A dose adjustment is not usually necessary in elderly patients up to 75 years without clinically manifest hepatic or renal insufficiency. In elderly patients over 75 years elimination may be prolonged. Therefore, if necessary, the dosage interval is to be extended according to the patient's requirements.

Renal insufficiency/dialysis and hepatic impairment:

In patients with renal and/or hepatic insufficiency the elimination of Protradon is delayed. In these patients prolongation of the dosage intervals should be carefully considered according to the patients requirements. In cases of severe renal and/or severe hepatic insufficiency Protradon drops are not recommended.

Method of administration

The drops should be administered orally and be diluted with water before administration, independent of meals.

The lowest analgesically effective dose should generally be selected. Daily doses of 400 mg active substance should not be exceeded, except in special clinical circumstances.

Protradon drops should under no circumstances be administered for longer than absolutely necessary. If long-term pain treatment with Protradon drops is necessary in view of the nature and severity of the illness, then careful and regular monitoring should be carried out (if necessary with breaks in treatment) to establish whether and to what extent further treatment is necessary.

Protradon drops is contraindicated

- in hypersensitivity to Protradon or any of the excipients ,

- in acute intoxication with alcohol, hypnotics, analgesics, opioids or other psychotropic medicinal products,

- in patients who are receiving MAO inhibitors or who have taken them within the last 14 days ,

- in patients with epilepsy not adequately controlled by treatment,

- for use in narcotic withdrawal treatment.

Protradon drops may only be used with particular caution in opioid-dependent patients, patients with head injury, shock, a reduced level of consciousness of uncertain origin, disorders of the respiratory centre or function, increased intracranial pressure.

In patients sensitive to opiates Protradon drops should only be used with caution.

Care should be taken when treating patients with respiratory depression, or if concomitant CNS depressant drugs are being administered , or if the recommended dosage is significantly exceeded as the possibility of respiratory depression cannot be excluded in these situations.

Convulsions have been reported in patients receiving Protradon at the recommended dose levels. The risk may be increased when doses of Protradon hydrochloride exceed the recommended upper daily dose limit (400 mg). In addition, Protradon may increase the seizure risk in patients taking other medicinal products that lowers the seizure threshold. Patients with epilepsy or those susceptible to seizures should only be treated with Protradon if there are compelling circumstances.

Protradon has a low dependence potential. On long-term use tolerance, psychic and physical dependence may develop. In patients with a tendency to drug abuse or dependence, treatment with Protradon drops should only be carried out for short periods under strict medical supervision.

Protradon is not suitable as a substitute in opioid-dependent patients. Although it is an opioid agonist, Protradon cannot suppress morphine withdrawal symptoms.

Patients with rare hereditary problems of fructose intolerance, glucose-galactose malabsorption or sucrase-isomaltase insufficiency should not take this medicine.

Even when taken according to instructions, Protradon drops may cause effects such as somnolence and dizziness and therefore may impair the reactions of drivers and machine operators. This applies particularly in conjunction with alcohol and other psychotropic substances.

This medicine can impair cognitive function and can affect a patient's ability to drive safely. This class of medicine is in the list of drugs included in regulations under 5a of the Road Traffic Act 1988. When prescribing this medicine, patients should be told:

- The medicine is likely to affect your ability to drive

- Do not drive until you know how the medicine affects you

- It is an offence to drive while under the influence of this medicine

- However, you would not be committing an offence (called 'statutory defence') if:

o The medicine has been prescribed to treat a medical or dental problem and

o You have taken it according to the instructions given by the prescriber and in the information provided with the medicine and

o It was not affecting your ability to drive safely

The most commonly reported adverse reactions are nausea and dizziness, both occurring in more than 10 % of patients.

The frequencies are defined as follows:

Immune system disorders:

Uncommon: toxic epidermal necrolysis (TEN) and Stevens-Johnson-syndrome (SJS), and cross reactivity with non steroidal anti-inflammatory drugs

Cardiovascular disorders:

Uncommon: cardiovascular regulation (palpitation, tachycardia, postural hypotension or cardiovascular collapse). These adverse reactions may occur especially on intravenous administration and in patients who are physically stressed.

Rare: bradycardia, increase in blood pressure

Metabolism and nutrition disorders

Not known: hypoglycaemia, hyponatraemia

Nervous system disorders:

Very common: dizziness

Common: headache, drowsiness, somnolence

Rare: changes in appetite, paraesthesia, tremor, respiratory depression, epileptiform convulsions, involuntary muscle contractions, abnormal coordination, syncope, hypertonia and dysgeusia. If the recommended doses are considerably exceeded and other centrally depressant substances are administered concomitantly , respiratory depression may occur. Epileptiform convulsions occurred mainly after administration of high doses of Protradon or after concomitant treatment with medicinal products which can lower the seizure threshold.

Not known: speech disorders

Psychiatric disorders:

Rare: delirium, hallucinations, confusion, sleep disturbance, anxiety and nightmares. Psychic adverse reactions may occur following administration of Protradon drops which vary individually in intensity and nature (depending on personality and duration of treatment). These include changes in mood (usually elation, occasionally dysphoria), changes in activity (usually suppression, occasionally increase) and changes in cognitive and sensorial capacity (e.g. decision behaviour, perception disorders). Dependence may occur. Suicidal ideation, drug abuse and addiction.

Eye disorders:

Rare: miosis, blurred vision

Not known: mydriasis

Respiratory disorders:

Rare: dyspnoea. Worsening of asthma has been reported, though a causal relationship has not been established.

Gastrointestinal disorders:

Very common: nausea

Common: constipation, dry mouth, vomiting, dyspepsia, abdominal pain

Uncommon: anorexia, retching, gastrointestinal irritation (a feeling of pressure in the stomach, bloating), diarrhoea

Skin and subcutaneous tissue disorders:

Common: sweating

Uncommon: dermal reactions (e.g. pruritus, rash, urticaria)

Musculo-skeletal disorders:

Rare: motorial weakness

Hepatobiliary disorders:

Very rare: In a few isolated cases an increase in liver enzyme values has been reported in a temporal connection with the therapeutic use of Protradon.

Renal and urinary disorders:

Rare: micturition disorders (difficulty in passing urine, dysuria and urinary retention)

Reproductive system and breast disorders:

Common: menopausal symptoms

Rare: menstrual disorders

General disorders:

Common: fatigue, asthenia, malaise

Rare: weight loss, allergic reactions (e.g. dyspnoea, bronchospasm, wheezing, angioneurotic oedema) and anaphylaxis; symptoms of withdrawal reactions, similar to those occurring during opiate withdrawal, may occur as follows: agitation, anxiety, nervousness, insomnia, hyperkinesia, tremor and gastrointestinal symptoms. Other symptoms that have very rarely been seen with Protradon discontinuation include: panic attacks, severe anxiety, hallucinations, paraesthesias, tinnitus and unusual CNS symptoms (i.e. confusion, delusions, depersonalization, derealization, paranoia).

Symptoms:

In principle, on intoxication with Protradon symptoms similar to those of other centrally acting analgesics (opioids) are to be expected. These include in particular miosis, vomiting, cardiovascular collapse, consciousness disorders up to coma, convulsions and respiratory depression up to respiratory arrest.

Treatment:

The general emergency measures apply. Keep open the respiratory tract (aspiration!), maintain respiration and circulation depending on the symptoms.

The antidote for respiratory depression is naloxone. In animal experiments naloxone had no effect on convulsions. In such cases diazepam should be given intravenously.

In case of intoxication with oral formulations, gastrointestinal decontamination with activated charcoal or by gastric lavage is only recommended within 2 hours after Protradon intake. Gastrointestinal decontamination at a later time point may be useful in case of intoxication with exceptionally large quantities or prolonged-release formulations.

Protradon is minimally eliminated from the serum by haemodialysis or haemofiltration. Therefore treatment of acute intoxication with Protradon drops with haemodialysis or haemofiltration alone is not suitable for detoxification.

Pharmacotherapeutic group: other opioids; ATC-code: N 02 AX02.

Protradon is a centrally-acting opioid analgesic. It is a non-selective pure agonist at µ, δ and κ opioid receptors with a higher affinity for the µ receptor. Other mechanisms which contribute to its analgesic effect are inhibition of neuronal re-uptake of noradrenaline and enhancement of serotonin release.

Protradon has an antitussive effect. In contrast to morphine, analgesic doses of Protradon over a wide range have no respiratory-depressant effect. Also gastrointestinal motility is less affected. Effects on the cardiovascular system tend to be slight. The potency of Protradon is reported to be 1/10 (one tenth) to 1/6 (one sixth) that of morphine.

More than 90% of Protradon drops is absorbed after oral administration. The mean absolute bioavailability is approximately 70 %, irrespective of the concomitant intake of food. The difference between absorbed and non-metabolised available Protradon is probably due to the low first-pass effect. The first-pass effect after oral administration is a maximum of 30 %. Maximal serum concentrations are reached after 1 hour.

Protradon has a high tissue affinity (V_d,ß = 203 ± 40 l). It has a plasma protein binding of about 20 %.

Protradon passes the blood-brain and placental barriers. Very small amounts of the substance and its O-desmethyl derivative are found in the breast-milk (0.1 % and 0.02 % respectively of the applied dose).

Elimination half-life t_1/2,ß is approximately 6 h, irrespective of the mode of administration. In patients above 75 years of age it may be prolonged by a factor of approximately 1.4.

In humans Protradon is mainly metabolised by means of N- and O-demethylation and conjugation of the O-demethylation products with glucuronic acid. Only O-desmethylProtradon is pharmacologically active. There are considerable interindividual quantitative differences between the other metabolites. So far, eleven metabolites have been found in the urine. Animal experiments have shown that O-desmethylProtradon is more potent than the parent substance by the factor 2 - 4. Its half-life t_1/2,ß (6 healthy volunteers) is 7.9 h (range 5.4 - 9.6 h) and is approximately that of Protradon.

The inhibition of one or both types of the isoenzymes CYP3A4 and CYP2D6 involved in the biotransformation of Protradon may affect the plasma concentration of Protradon or its active metabolite. Up to now, clinically relevant interactions have not been reported.

Protradon and its metabolites are almost completely excreted via the kidneys. Cumulative urinary excretion is 90 % of the total radioactivity of the administered dose. In case of impaired hepatic or renal function the half-life may be slightly prolonged. In patients with cirrhosis of the liver, elimination half-lives of 13.3 ± 4.9 h (Protradon) and 18.5 ± 9.4 h (O-desmethylProtradon), in an extreme case 22.3 h and 36 h respectively, have been determined. In patients with renal insufficiency (creatinine clearance < 5 ml/min) the values were 11 ± 3.2 h and 16.9 ± 3 h, in an extreme case 19.5 h and 43.2 h respectively.

Protradon has a linear pharmacokinetic profile within the therapeutic dosage range.

The relationship between serum concentrations and the analgesic effect is dose-dependent, but varies considerably in isolated cases. A serum concentration of 100 - 300 ng/ml is usually effective.

On repeated oral and parenteral administration of Protradon for 6 - 26 weeks in rats and dogs and oral administration for 12 months in dogs haematological, clinico-chemical and histological investigations showed no evidence of any substance-related changes. Central nervous manifestations only occurred after high doses considerably above the therapeutic range: restlessness, salivation, convulsions, and reduced weight gain. Rats and dogs tolerated oral doses of 20 mg/kg and 10 mg/kg body weight respectively, and dogs rectal doses of 20 mg/kg body weight without any reactions.

In rats Protradon dosages from 50 mg/kg/day upwards caused toxic effects in dams and raised neonate mortality. In the offspring retardation occurred in the form of ossification disorders and delayed vaginal and eye opening. Male fertility was not affected. After higher doses (from 50 mg/kg/day upwards) females exhibited a reduced pregnancy rate. In rabbits there were toxic effects in dams from 125 mg/kg upwards and skeletal anomalies in the offspring.

In some in-vitro test systems there was evidence of mutagenic effects. In-vivo studies showed no such effects. According to knowledge gained so far, Protradon can be classified as non-mutagenic.

Studies on the tumorigenic potential of Protradon hydrochloride have been carried out in rats and mice. The study in rats showed no evidence of any substance-related increase in the incidence of tumours. In the study in mice there was an increased incidence of liver cell adenomas in male animals (a dose-dependent, non-significant increase from 15 mg/kg upwards) and an increase in pulmonary tumours in females of all dosage groups (significant, but not dose-dependent).

Not applicable.

No special requirements.

Any unused product or waste material should be disposed of in accordance with local requirements.