Varenicline (Page 4 of 12)
There are no data on the presence of varenicline in human milk, the effects on the breastfed infant, or the effects on milk production. In animal studies varenicline was present in milk of lactating rats [see Data]. However, due to species-specific differences in lactation physiology, animal data may not reliably predict drug levels in human milk. The lack of clinical data during lactation precludes a clear determination of the risk of varenicline to an infant during lactation; however the developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for varenicline and any potential adverse effects on the breastfed child from varenicline or from the underlying maternal condition.
Because there are no data on the presence of varenicline in human milk and the effects on the breastfed infant, breastfeeding women should monitor their infant for seizures and excessive vomiting, which are adverse reactions that have occurred in adults that may be clinically relevant in breastfeeding infants.
In a pre- and postnatal development study, pregnant rats received up to 15 mg/kg/day of oral varenicline succinate through gestation and lactation Mean serum concentrations of varenicline in the nursing pups were 5-22% of maternal serum concentrations.
8.4 Pediatric Use
Varenicline is not recommended for use in pediatric patients 16 years of age or younger because its efficacy in this population was not demonstrated.
Single and multiple-dose pharmacokinetics of varenicline have been investigated in pediatric patients aged 12 to 17 years old (inclusive) and were approximately dose-proportional over the 0.5 mg to 2 mg daily dose range studied. Steady-state systemic exposure in adolescent patients of bodyweight >55 kg, as assessed by AUC (0-24), was comparable to that noted for the same doses in the adult population. When 0.5 mg BID was given, steady-state daily exposure of varenicline was, on average, higher (by approximately 40%) in adolescent patients with bodyweight ≤ 55 kg compared to that noted in the adult population.
Additional information describing a clinical study in which efficacy was not demonstrated in pediatric patients is approved for Pfizer Inc.’s Chantix (varenicline) tablets. However, due to Pfizer Inc.’s marketing exclusivity rights, this drug product is not labeled with that pediatric information.
8.5 Geriatric Use
A combined single- and multiple-dose pharmacokinetic study demonstrated that the pharmacokinetics of 1 mg varenicline given once daily or twice daily to 16 healthy elderly male and female smokers (aged 65 to 75 years) for 7 consecutive days was similar to that of younger subjects. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.
Varenicline is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function [see Dosage and Administration (2.2)].
No dosage adjustment is recommended for elderly patients.
8.6 Renal Impairment
Varenicline is substantially eliminated by renal glomerular filtration along with active tubular secretion. Dose reduction is not required in patients with mild to moderate renal impairment. For patients with severe renal impairment (estimated creatinine clearance <30 mL/min), and for patients with end-stage renal disease undergoing hemodialysis, dosage adjustment is needed [see Dosage and Administration (2.2), Clinical Pharmacology (12.3)].
9 DRUG ABUSE AND DEPENDENCE
9.1 Controlled Substance
Varenicline is not a controlled substance.
Fewer than 1 out of 1,000 patients reported euphoria in clinical trials with varenicline. At higher doses (greater than 2 mg), varenicline produced more frequent reports of gastrointestinal disturbances such as nausea and vomiting. There is no evidence of dose-escalation to maintain therapeutic effects in clinical studies, which suggests that tolerance does not develop. Abrupt discontinuation of varenicline was associated with an increase in irritability and sleep disturbances in up to 3% of patients. This suggests that, in some patients, varenicline may produce mild physical dependence which is not associated with addiction.
In a human laboratory abuse liability study, a single oral dose of 1 mg varenicline did not produce any significant positive or negative subjective responses in smokers. In non-smokers, 1 mg varenicline produced an increase in some positive subjective effects, but this was accompanied by an increase in negative adverse effects, especially nausea. A single oral dose of 3 mg varenicline uniformly produced unpleasant subjective responses in both smokers and non-smokers.
Animals Studies in rodents have shown that varenicline produces behavioral responses similar to those produced by nicotine. In rats trained to discriminate nicotine from saline, varenicline produced full generalization to the nicotine cue. In self-administration studies, the degree to which varenicline substitutes for nicotine is dependent upon the requirement of the task. Rats trained to self-administer nicotine under easy conditions continued to self-administer varenicline to a degree comparable to that of nicotine; however in a more demanding task, rats self-administered varenicline to a lesser extent than nicotine. Varenicline pretreatment also reduced nicotine self-administration.
In case of overdose, standard supportive measures should be instituted as required.
Varenicline has been shown to be dialyzed in patients with end-stage renal disease [see Clinical Pharmacology (12.3)] , however, there is no experience in dialysis following overdose.
Varenicline tablets contain varenicline (as the tartrate salt), which is a partial nicotinic agonist selective for α 4 β 2 nicotinic acetylcholine receptor subtypes.
Varenicline, as the tartrate salt of maltodextrin premix (1:1:10), is a powder which is a off-white to pinkish brown color with the following chemical name: 7,8,9,10-tetrahydro-6,10-methano-6 H -pyrazino[2,3- h]benzazepine, (2 R ,3 R)-2,3-dihydroxybutanedioate with maltodextrin (1:1:10). It is soluble in water, practically insoluble in acetone and methylene dichloride. Varenicline tartrate has a molecular weight of 361.35 Daltons and maltodextrin, and a molecular formula of C 13 H 13 N 3 • C 4 H 6 O 6 and maltodextrin. The chemical structure is:
Varenicline tablets are supplied for oral administration in two strengths: a 0.5 mg circular, biconvex, white to off-white film-coated tablets, debossed with “P” on one side and “155” on other side and a 1 mg circular, biconvex, light blue film-coated tablets, debossed with “P” on one side and “156” on other side. Each 0.5 mg varenicline tablet contains 0.85 mg of varenicline tartrate equivalent to 0.5 mg of varenicline free base; each 1 mg varenicline tablet contains 1.71 mg of varenicline tartrate equivalent to 1 mg of varenicline free base. The following inactive ingredients are included in the tablets: croscarmellose sodium, maltodextrin, microcrystalline cellulose, stearic acid. The tablets are film-coated with a coating material containing hydroxypropyl cellulose, hypromellose, talc, and titanium dioxide. In addition to these, the 1 mg tablet film coating includes FD&C blue #2/indigo carmine aluminum lake and iron oxide yellow.
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