Cetirizine: a review of its use in children with allergic disorders

Prescribed drugs containing nitrogen heterocycles: an overview

Heteroatoms as well as heterocyclic scaffolds are frequently present as the common cores in a plethora of active pharmaceuticals natural products. Statistically, more than 85% of all biologically active compounds are heterocycles or comprise a heterocycle and most frequently, nitrogen heterocycles as a backbone in their complex structures. These facts disclose and emphasize the vital role of heterocycles in modern drug design and drug discovery. In this review, we try to present a comprehensive overview of top prescribed drugs containing nitrogen heterocycles, describing their pharmacological properties, medical applications and their selected synthetic pathways. It is worth mentioning that the reported examples are actually limited to current top selling drugs, being or containing N-heterocycles and their synthetic information has been extracted from both scientific journals and the wider patent literature.

Retrospective population pharmacokinetics of levocetirizine in atopic children receiving cetirizine: the ETAC study

AIMS

To evaluate the population pharmacokinetics of levocetirizine in young children receiving long-term treatment with cetirizine.

METHODS

Data were available from a randomized, double-blind, parallel group and placebo-controlled study of cetirizine in 343 young children between 12 and 24 months of age at entry, who were at high risk of developing asthma, but were not yet affected (ETAC study). Infants received oral drops of cetirizine at 0.25 mg kg(-1) twice daily for 18 months. Plasma concentration of the active enantiomer levocetirizine was determined in blood samples collected at months 3, 12 and 18 (1-3 samples per child). A one-compartment open model was fitted to the data using nonlinear mixed effects modelling (NONMEM). The influence of weight, age, gender, BSA and other covariates on CL/F and V/F was evaluated.

RESULTS

CL/F increased linearly with weight by 0.044 l h(-1) kg(-1) over an intercept of 0.244 l h(-1), and V/F increased linearly with weight by 0.639 l kg(-1). Population estimates in children with weights of 8 and 20 kg were 0.60 and 1.13 l h(-1) for CL/F, and 5.1 and 12.8 l for V/F, respectively, with interpatient variabilities of 24.4% and 14.7%. Weight-normalized estimates of CL/F and V/F were higher than in adults. The estimated relative bioavailability was 0.28 in 12% of instances of suspected noncompliance. Levocetirizine pharmacokinetics were not influenced by severe allergy or aeroallergen sensitization. Results on the effects of concomitant medications or diseases were inconclusive due to limited positive cases. AUC(ss), calculated in compliant subjects using posterior estimates of the final model, was 1952 (1227-3319) microg l(-1) h (mean, min-max), a value similar to that in adults after intake of 5 mg oral solution (2036 (1414-2827) microg l(-1) h.

CONCLUSIONS

The model suggests that administration of levocetirizine 0.125 mg kg(-1) twice daily in children 12-48 months of age or weighing 8-20 kg yields the same exposure as in adults taking the recommended dose of 5 mg once daily.

Cetirizine: a review of its use in allergic disorders

Cetirizine is a selective, second-generation histamine H1 receptor antagonist, with a rapid onset, a long duration of activity and low potential for interaction with drugs metabolised by the hepatic cytochrome P450 system. Cetirizine was generally more effective than other H1 receptor antagonists at inhibiting histamine-induced wheal and flare responses. Cetirizine is an effective and well tolerated agent for the treatment of symptoms of seasonal allergic rhinitis (SAR), perennial allergic rhinitis (PAR) and chronic idiopathic urticaria (CIU) in adult, adolescent and paediatric patients. In adults with these allergic disorders, cetirizine was as effective as conventional dosages of ebastine (SAR, PAR, CIU), fexofenadine (SAR), loratadine (SAR, CIU) or mizolastine (SAR). This agent was significantly more effective, and with a more rapid onset of action, than loratadine in 2-day studies in environmental exposure units (SAR). In paediatric patients, cetirizine was as at least as effective as chlorphenamine (chlorpheniramine) [SAR], loratadine (SAR, PAR) and oxatomide (CIU) in the short term, and more effective than oxatomide and ketotifen (PAR) in the long term. Cetirizine was effective in reducing symptoms of allergic asthma in adults and reduced the relative risk of developing asthma in infants with atopic dermatitis sensitised to grass pollen or house dust mite allergens. It had a corticosteroid-sparing effect in infants with severe atopic dermatitis and was effective in ameliorating reactions to mosquito bites in adults. Cetirizine was well tolerated in adults, adolescents and paediatric patients with allergic disorders. In adult, adolescent and paediatric patients aged 2-11 years, the incidence of somnolence with cetirizine was dose related and was generally similar to that with other second-generation H1 receptor antagonists. Although, its sedative effect was greater than that of fexofenadine in some clinical trials and that of loratadine or fexofenadine in a postmarketing surveillance study. In infants aged 6-24 months, the tolerability profile of cetirizine was similar to that of placebo. Cetirizine did not have any adverse effects on cognitive function in adults, or cognitive function, behaviour or achievement of psychomotor milestones in paediatric patients. Cetirizine was not associated with cardiotoxicity.

CONCLUSION

Cetirizine is well established in the treatment of symptoms of SAR, PAR or CIU. It demonstrated a corticosteroid-sparing effect and reduced the relative risk of developing asthma in sensitised infants with atopic dermatitis. Cetirizine was effective in the treatment of allergic cough and mosquito bites; however, its precise role in these indications has yet to be clearly established. On the basis of its favourable efficacy and tolerability profile and rapid onset of action, cetirizine provides an important option for the treatment of a wide range of allergic disorders.

Retrospective population pharmacokinetic analysis of cetirizine in children aged 6 months to 12 years

AIMS

To evaluate retrospectively the population pharmacokinetics of cetirizine, a second-generation antihistamine, in children.

METHODS

Data were pooled from six clinical trials, in which cetirizine was administered orally in various formulations and in single and multiple dosage regimens. The population consisted of 112 children (33 female and 79 male) aged 6 months to 12 years. A one-compartment open model with first-order absorption and elimination was fitted to the plasma concentration-time profiles using nonlinear mixed effects modelling with first-order estimation.

RESULTS

A linear association was found between apparent clearance (CL/F) and age with the former increasing by 0.12 l h(-1) per year. The intercept of the relationship was slightly lower for female children (0.59 vs. 0.77 l h(-1) in male). The population estimate of CL/F for an average age of 7 years was 1.61 and 1.43 l h(-1) for male and female children, respectively. A linear association was found between apparent volume of distribution (V/F) and age with the former increasing by 1.4 l year(-1), with an intercept of 4.0 l. The population estimate of V/F for an average age of 7 years was 13.9 l. The magnitudes of interpatient variability were 35.6% for CL/F and 19.7% for V/F. The magnitude of residual variability in cetirizine concentrations was 26.9%.

CONCLUSIONS

Population analysis predicts a linear increase in cetirizine CL/F and V/F with age, with CL/F being slightly lower in female children, relative to males of the same age. However, this gender difference probably has no clinical consequences. Since V/F increased more rapidly with age than CL/F, a nonlinear increase in half-life was seen, from < 4 h in infants to near the adult value at 12 years of age. The current recommended dosing regimens that younger children should receive lower but more frequent doses, are confirmed by the present analysis.

Cetirizine, an H1-receptor antagonist, suppresses the expression of macrophage migration inhibitory factor: its potential anti-inflammatory action

BACKGROUND

H1-receptor antagonists are often effective in the treatment of allergic disorders such as atopic dermatitis. Cetirizine, a putative H1-receptor antagonist, has recently been shown to have anti-inflammatory properties through the inhibition of leucocyte recruitment and activation, and by the reduction of ICAM-1 expression on keratinocytes.

OBJECTIVE

To further elucidate the anti-inflammatory properties of cetirizine, we first examined its effects on antigen-induced eosinophilia and neutrophila in vivo. We then examined the anti-inflammatory effects of cetirizine on a human keratinocyte A431cell line.

METHODS

Mice were sensitized subcutaneously with ragweed pollen and were challenged intraperitoneally with the allergen. Cetirizine diluted in sterile water (0-20 mg/kg) or only sterile water was administered orally. Peritoneal cells were obtained at 8 and 24 h after challenge. The eosinophilia and neutrophilia induced by ragweed pollen extract were quantitated. Macrophage migration inhibitory factor (MIF), macrophage inflammatory protein 2 (MIP-2) and eotaxin contents of peritoneal fluid were also measured by mouse ELISA. The effects of cetirizine on MIF-induced IL-8 production in A431 cells were examined by ELISA. The effects of cetirizine on MIF expression and production in A431 cells were examined by human MIF ELISA and Northern blot analysis.

RESULTS

Eosinophilia and neutrophilia induced by ragweed pollen extract were found to be significantly reduced in cetirizine-treated mice (20 mg/kg). MIF, a pleuripotent cytokine, was significantly decreased at 8 and 24 h in the peritoneal fluid by cetirizine treatment. MIP-2 and eotaxin were also decreased 8 and 24 h, respectively, after challenge in the peritoneal fluid with cetirizine treatment. MIF stimulates IL-8 production in A431 cells. We found that MIF production in A431 cells was inhibited by 10 microm cetirizine. Consistent with this, cetirizine significantly inhibited MIF-induced IL-8 production.

CONCLUSION

These results suggest that cetirizine exerts its anti-inflammatory effects by inhibiting MIF as well as IL-8 production, such as those involved in inflammatory allergic skin disease, suggesting a broad spectrum of action beyond its mere H1-receptor-antagonistic function.

Safety of cetirizine in infants 6 to 11 months of age: a randomized, double-blind, placebo-controlled study

BACKGROUND

H(1)-antihistamines are widely used for symptom relief in allergic disorders in infants and children; however, there are few prospective, randomized, double-blind, controlled studies of these medications in young children, and to date, no such studies have been conducted in infants.

OBJECTIVE

This prospective, randomized, parallel-group, double-blind, placebo-controlled study was designed to evaluate the safety of the H(1)-antihistamine cetirizine, particularly with regard to central nervous system and cardiac effects, in infants age 6 to 11 months, inclusive.

METHODS

Infants who met the entry criteria for age and had a history of treatment with an H(1)-antihistamine for an allergic or other disorder were randomized to receive 0.25 mg/kg cetirizine orally or matching placebo twice daily orally for 1 week.

RESULTS

The mean daily dose in cetirizine-treated infants was 4.5 +/- 0.7 mg (SD). No differences in all-cause or treatment-related adverse events were observed between the cetirizine- and placebo-treated groups. A trend was observed toward fewer adverse events and sleep-related disturbances in the cetirizine group compared with the placebo group. No prolongation in the linear corrected QT interval was observed in cetirizine-treated infants compared with either baseline values or with values in placebo-treated infants.

CONCLUSIONS

We have documented the safety of cetirizine in this short-term investigation, the first randomized, double-blind, placebo-controlled study of any H(1)-antihistamine in infants. Additional prospective, randomized, double-blind, placebo-controlled, long-term studies of cetirizine and other H(1)-antihistamines are needed in this population.

Cetirizine/pseudoephedrine

Cetirizine is the carboxylated metabolite of hydroxyzine, and has high specific affinity for histamine H(1) receptors. Pseudoephedrine is a sympathomimetic drug that acts directly on alpha-adrenergic receptors. black triangle Cetirizine/pseudoephedrine 5/120 mg twice daily was significantly more effective than intranasal budesonide 100 microg or placebo at improving nasal obstruction, nasal patency and reducing the volume of nasal secretion, and was significantly more effective than intranasal xylometazoline 0.1% with respect to nasal secretion, during house dust mite faeces challenge in three randomised, cross- over studies among volunteers with seasonal or perennial rhinitis. The onset of action of cetirizine/pseudoephedrine was reported to be approximately 30 minutes. black triangle The bioavailability of cetirizine and pseudoephedrine is similar after administration of cetirizine/pseudoephedrine 5/120 mg bilayer tablets or coadministration of cetirizine 5 mg tablets plus pseudoephedrine sustained-release (SR) 120 mg caplets. black triangle Cetirizine 5mg plus pseudoephedrine SR 120 mg twice daily for 2 to 3 weeks was significantly more effective than each drug given alone at reducing mean total symptom scores for seasonal or perennial allergic rhinitis in two randomised, double-blind, multicentre trials. In both studies, the mean proportion of days during which the five measured symptoms (nasal obstruction, sneezing, rhinorrhoea, nasal pruritus and ocular pruritus) were absent or mild was significantly greater in recipients of the cetirizine plus pseudoephedrine SR. black triangle In one study, cetirizine 5 mg plus pseudoephedrine SR 120 mg was significantly more effective at reducing nasal obstruction than either drug alone. black triangle Cetirizine 5mg plus pseudoephedrine SR 120 mg twice daily for 2 to 3 weeks was well tolerated in patients with seasonal or perennial allergic rhinitis. The most common adverse events were dry mouth, insomnia, headache, somnolence, asthenia and nervousness.