How should I take Leerex?
Take Leerex exactly as directed. If you do not understand these directions, ask your pharmacist, nurse, or doctor to explain them to you.
Shake the liquid form of Leerex well before measuring a dose. To ensure that you get a correct dose, measure the suspension with a dose-measuring spoon, dropper, or cup, not a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist where you can get one. Do not mix the suspension with any other liquid before taking it. Mixing it with another liquid may change the way the medication is absorbed in the body. Leerex can be taken with food if stomach upset occurs. Do not take more of this medication than is recommended. An overdose of this medication can cause serious harm. Codeine (Leerex) may be habit forming. Physical and/or psychological dependence can occur, and withdrawal effects are possible if the medication is stopped suddenly after prolonged or high-dose treatment. Do not stop taking Leerex suddenly without first talking to your doctor if you have been taking it continuously for more than 5 to 7 days. Your doctor may want to gradually reduce the dose. Store Leerex at room temperature away from moisture and heat.
Leerex administration
Administer with or without food. Shake extended-release suspension well before use. Administer with an accurate milliliter oral measuring device; do not use a household teaspoon to measure dose (overdosage may occur). Do not dilute with fluids or mix together with other drugs.
Leerex pharmacology
Pharmacodynamics
Codeine (Leerex)The precise mechanism of action of Codeine (Leerex) and other opiates is not known but it is believed to act in the medulla with depression of the cough center and to a lesser degree the respiratory center.
Chlorpheniramine (Leerex)
Chlorpheniramine (Leerex) is a propylamine derivative antihistamine (H1-receptor antagonist) of the alkylamine class that also possesses anticholinergic and sedative activity. It prevents released histamine from dilating capillaries and causing edema of the respiratory mucosa.
Pharmacokinetics
The bioavailability of Leerex has been assessed in single- and multiple-dose crossover studies in healthy adults. In a single-dose study, pharmacokinetic parameters for Leerex were evaluated in 20 fasting subjects and compared to two doses of an immediate-release reference solution containing 20 mg Codeine (Leerex) and 4 mg Chlorpheniramine (Leerex) maleate. In a separate study, single doses of Leerex were administered to 36 subjects, under both fed and fasted conditions. In a multi-dose study, the steady state pharmacokinetic parameters of Codeine (Leerex) and Chlorpheniramine (Leerex) were compared in 26 subjects who received Leerex administered twice daily and an immediate-release reference solution administered four times daily for one week.
Absorption
In two single dose studies with Leerex in fasting, healthy volunteers, Codeine (Leerex) mean (S.D.) peak plasma concentrations were 53.8 (13.4) ng/mL and 61.7 (18.5) ng/mL. Chlorpheniramine (Leerex) mean (S.D.) peak plasma concentrations were 7.9 (1.6) ng/mL and 7.4 (1.6) ng/mL. Peak plasma Codeine (Leerex) levels were reached approximately 2.5 to 3 hours following dosing. Peak plasma Chlorpheniramine (Leerex) levels were reached approximately 6.5 to 7 hours following dosing. Peak plasma concentrations of Codeine (Leerex) and Chlorpheniramine (Leerex) were reached approximately 2.7 and 9 hours respectively after dosing with the immediate-release reference solution.
Following multiple dosing with Leerex, Codeine (Leerex) mean (S.D.) peak plasma concentrations of 100.5 (26.8) ng/mL were reached at approximately 2 hours. Chlorpheniramine (Leerex) mean (S.D.) peak concentrations of 35.8 (10.0) ng/mL were reached approximately 3 hours following multiple dosing. Peak plasma concentrations of Codeine (Leerex) and Chlorpheniramine (Leerex) were reached approximately 1 and 3 hours respectively after dosing with the immediate-release reference solution.
Distribution
Codeine (Leerex) has been reported to have an apparent volume of distribution of approximately 3-6 L/kg, indicating extensive distribution of the drug into tissues. About 7-25% of Codeine (Leerex), reportedly, is bound to plasma proteins. Codeine (Leerex) passes the blood brain barrier and the placental barrier. Small amounts of Codeine (Leerex) and its metabolite, morphine, are transferred to human breast milk.
Chlorpheniramine (Leerex) is widely distributed throughout the tissues of the body, including the central nervous system. It reportedly has an apparent steady-state volume of distribution of approximately 3.2 L/kg in adults and children and is about 70% bound to plasma proteins. Chlorpheniramine (Leerex) and its metabolites likely cross the placental barrier and are excreted into human breast milk.
Food Effects
The bioavailability of Leerex Extended-Release Suspension was not affected when administered after a high fat meal. In a two-way crossover study, pharmacokinetic parameters were evaluated in 36 healthy subjects and no differences between fed and fasted groups were observed for either Cmax or AUC for either Codeine (Leerex) or Chlorpheniramine (Leerex). A statistically significant increase in Tmax for Chlorpheniramine (Leerex) from 6.3 hours to 9.1 hours was observed after a high fat meal; however this increase is unlikely to be clinically important.
Metabolism
Codeine (Leerex) is metabolized by conjugation with glucuronic acid to Codeine (Leerex)-6-glucuronide, and to a minor extent via O-demethylation to morphine (approximately 10% of administered dose) and via N-demethylation to norcodeine (approximately 10% of administered dose). Cytochrome P-450 2D6 is the major enzyme mediating O-demethylation of Codeine (Leerex) to morphine. Norcodeine formation is predominately catalyzed by cytochrome P-450 3A4 mediated N-demethylation. Norcodeine and morphine are further metabolized by conjugation with glucuronic acid. These metabolites and their conjugates are pharmacologically active. Whether Codeine (Leerex)-6-glucuronide has pharmacological activity is unknown, but activity similar to Codeine (Leerex) itself is expected.
Chlorpheniramine (Leerex) is rapidly and extensively metabolized via demethylation in the liver, forming mono- and didesmethyl derivatives. Oxidative metabolism of Chlorpheniramine (Leerex) is catalyzed by cytochrome P-450 2D6.
Elimination
Approximately 90% of the total dose of Codeine (Leerex) is excreted through the kidneys, of which approximately 10% is unchanged Codeine (Leerex).
Plasma half-lives of Codeine (Leerex) have been reported to be approximately 3 hours.
Chlorpheniramine (Leerex) and its metabolites are primarily excreted through the kidneys, with large individual variation. Urinary excretion depends on urine pH and flow rate.
Plasma half-lives for Chlorpheniramine (Leerex) have been reported to range from approximately 2 to 43 hours in adults and 5 to 16 hours in children.
References
- DailyMed. "CHLORPHENIRAMINE POLISTIREX; HYDROCODONE POLISTIREX: DailyMed provides trustworthy information about marketed drugs in the United States. DailyMed is the official provider of FDA label information (package inserts).". https://dailymed.nlm.nih.gov/dailyme... (accessed September 17, 2018).
- DailyMed. "CODEINE SULFATE: DailyMed provides trustworthy information about marketed drugs in the United States. DailyMed is the official provider of FDA label information (package inserts).". https://dailymed.nlm.nih.gov/dailyme... (accessed September 17, 2018).
- NCIt. "Codeine Phosphate: NCI Thesaurus (NCIt) provides reference terminology for many systems. It covers vocabulary for clinical care, translational and basic research, and public information and administrative activities.". https://ncit.nci.nih.gov/ncitbrowser... (accessed September 17, 2018).
Reviews
The results of a survey conducted on ndrugs.com for Leerex are given in detail below. The results of the survey conducted are based on the impressions and views of the website users and consumers taking Leerex. We implore you to kindly base your medical condition or therapeutic choices on the result or test conducted by a physician or licensed medical practitioners.User reports
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Information checked by Dr. Sachin Kumar, MD Pharmacology
