PALEXIA Oral solution Ref.[8095] Active ingredients: Tapentadol

The bioavailability as assessed by C_max and AUC and all other pharmacokinetic parameters determined for tapentadol after administration of 100 mg tapentadol as oral solution were similar compared to a 100 mg film-coated tablet (another oral immediate-release formulation). Therefore the information given below based on trials with film-coated tablets is also applicable to the oral solution.

Absorption

Tapentadol is rapidly and completely absorbed after oral administration of PALEXIA. Mean absolute bioavailability after single-dose administration (fasting) is approximately 32% due to extensive first-pass metabolism. Maximum serum concentrations of tapentadol are typically observed at around 1.25 hours after administration of film-coated tablets. Dose-proportional increases in the C_max and AUC values of tapentadol have been observed after administration of film-coated tablets over the oral therapeutic dose range.

A multiple (every 6 hour) dose trial with doses ranging from 75 to 175 mg tapentadol administered as film-coated tablets showed an accumulation ratio between 1.4 and 1.7 for the parent active substance and between 1.7 and 2.0 for the major metabolite tapentadol-O-glucuronide, which are primarily determined by the dosing interval and apparent half-life of tapentadol and its metabolite. Steady state serum concentrations of tapentadol are reached on the second day of the treatment regimen.

Food Effect

The AUC and C_max increased by 25% and 16%, respectively, when film-coated tablets were administered after a high-fat, high-calorie breakfast. The time to maximum plasma concentration was delayed by 1.5 hours under these conditions. Based on efficacy data obtained at early assessment time points during phase II/III, the food effect does not appear to be of clinical relevance PALEXIA may be given with or without food.

Distribution

Tapentadol is widely distributed throughout the body. Following intravenous administration, the volume of distribution (Vz) for tapentadol is 540 +/- 98 l.

The serum protein binding is low and amounts to approximately 20% mainly bound to albumin.

Metabolism

About 97% of the parent compound is metabolised. The major pathway of tapentadol metabolism is conjugation with glucuronic acid to produce glucuronides. After oral administration approximately 70% of the dose is excreted in urine as conjugated forms (55% glucuronide and 15% sulfate of tapentadol). Uridine diphosphate glucuronyl transferase (UGT) is the primary enzyme involved in the glucuronidation (mainly UGT1A6, UGT1A9 and UGT2B7 isoforms). A total of 3% of active substance is excreted in urine as unchanged active substance. Tapentadol is additionally metabolised to N-desmethyl tapentadol (13%) by CYP2C9 and CYP2C19 and to hydroxy tapentadol (2%) by CYP2D6, which are further metabolised by conjugation. Therefore, active substance metabolism mediated by cytochrome P450 system is of less importance than phase 2 conjugation.

None of the metabolites contributes to the analgesic activity.

Elimination

Tapentadol and its metabolites are excreted almost exclusively (99%) via the kidneys. The total clearance after intravenous administration is 1530 +/- 177 ml/min.

Special populations

Older people

The mean exposure (AUC) to tapentadol was similar in a trial with older subjects (65-78 years of age) compared to young adults (19-43 years of age), with a 16% lower mean C_max observed in the older subject group compared to young adult subjects.

Renal Impairment

AUC and C_max of tapentadol were comparable in subjects with varying degrees of renal function (from normal to severely impaired). In contrast, increasing exposure (AUC) to tapentadol-O-glucuronide was observed with increasing degree of renal impairment. In subjects with mild, moderate, and severe renal impairment, the AUC of tapentadol-O-glucuronide are 1.5-, 2.5-, and 5.5-fold higher compared with normal renal function, respectively.

Hepatic Impairment

Administration of tapentadol resulted in higher exposures and serum levels to tapentadol in subjects with impaired hepatic function compared to subjects with normal hepatic function. The ratio of tapentadol pharmacokinetic parameters for the mild and moderate hepatic impairment groups in comparison to the normal hepatic function group were 1.7 and 4.2, respectively, for AUC; 1.4 and 2.5, respectively, for C_max; and 1.2 and 1.4, respectively, for t_1/2.The rate of formation of tapentadol-O-glucuronide was lower in subjects with increased liver impairment.

Pharmacokinetic Interactions

Tapentadol is mainly metabolised by Phase 2 glucuronidation, and only a small amount is metabolised by Phase 1 oxidative pathways.

As glucuronidation is a high capacity/low affinity system, which is not easily saturated even in disease, and as therapeutic concentrations of active substances are generally well below the concentrations needed for potential inhibition of glucuronidation, any clinically relevant interactions caused by Phase 2 metabolism are unlikely to occur. In a set of drug-drug interaction trials using paracetamol, naproxen, acetylsalicylic acid and probenecid, a possible influence of these active substances on the glucuronidation of tapentadol was investigated. The trials with probe active substances naproxen (500 mg twice daily for 2 days) and probenecid (500 mg twice daily for 2 days) showed increases in AUC of tapentadol by 17% and 57%, respectively. Overall, no clinically relevant effects on the serum concentrations of tapentadol were observed in these trials.

Furthermore, interaction trials of tapentadol with metoclopramide and omeprazole were conducted to investigate a possible influence of these active substances on the absorption of tapentadol. These trials also showed no clinically relevant effects on tapentadol serum concentrations.

In vitro studies did not reveal any potential of tapentadol to either inhibit or induce cytochrome P450 enzymes. Thus, clinically relevant interactions mediated by the cytochrome P450 system are unlikely to occur.

Plasma protein binding of tapentadol is low (approximately 20%). Therefore, the likelihood of pharmacokinetic drug-drug interactions by displacement from the protein binding site is low.

Paediatric population

Absorption

In the paediatric population the maximum serum concentrations were observed at a similar time to adults, with no age related changes.

Food Effect

A dedicated food effect trial has not been performed in children and adolescents. In the phase III trial performed in children and adolescents tapentadol oral solution was given irrespective of food intake.

Based on efficacy data obtained during the phase III trial in children and adolescents, the food effect does not appear to be of clinical relevance. PALEXIA may be given with or without food.

Distribution

The volume of distribution per age group in children following oral administration of tapentadol and derived from population pharmacokinetic modelling (Pop PK) is shown in the following table:

Parameters based on new combined model.

Metabolism

In humans aged 5 months or more the metabolism of tapentadol is extensive.

Elimination

The paediatric clearance of tapentadol following oral administration and derived from Pop PK modelling for the different age groups is shown in the table below.

Parameters based on new combined model.

Special populations

Renal and Hepatic Impairment

PALEXIA has not been studied in children and adolescents with renal and hepatic impairment.

Pharmacokinetic Interactions

Dedicated drug-drug interaction trials have not been performed in children and adolescents.

Tapentadol was not genotoxic in bacteria in the Ames test. Equivocal findings were observed in an in vitro chromosomal aberration test, but when the test was repeated the results were clearly negative. Tapentadol was not genotoxic in vivo, using the two endpoints of chromosomal aberration and unscheduled DNA synthesis, when tested up to the maximum tolerated dose. Long-term animal studies did not identify a potential carcinogenic risk relevant to humans.

Tapentadol had no influence on male or female fertility in rats but there was reduced in utero survival at the high dose. It is not known whether this was mediated via the male or the female. Tapentadol showed no teratogenic effects in rats and rabbits following intravenous and subcutaneous exposure. However, delayed development and embryotoxicity were observed after administration of doses resulting in exaggerated pharmacology (mu-opioid related CNS effects related to dosing above the therapeutic range). After intravenous dosing in rats reduced in utero survival was seen. In rats tapentadol caused increased mortality of the F₁ pups that were directly exposed via milk between days 1 and 4 post partum already at dosages that did not provoke maternal toxicities. There were no effects on neurobehavioral parameters.

Excretion into breast milk was investigated in rat pups suckled by dams dosed with tapentadol. Pups were dose-dependently exposed to tapentadol and tapentadol O-glucuronide. It was concluded that tapentadol is excreted in milk.

Juvenile rats were treated from post-natal day 6 to day 90, which covered the period of development corresponding to infancy, childhood and adolescence in humans. During the first 3 days of treatment, a numerically higher incidence of mortality was observed at doses of ≥25 mg/kg/day with Tapentadol plasma exposure at the LOAEL comparable to the predicted clinical plasma exposure in children. Tapentadol was well tolerated in pups older than 10 days, There were no treatment-related clinical signs, effects on body weight, food consumption, pre-weaning or reproductive development, long-bone growth, motor activity, behaviour or learning and memory. Organ weights and macroscopic or microscopic evaluation showed no treatment-related changes. Tapentadol did not influence sexual development, mating or pregnancy parameters in the treated animals.