Erdosteine is a thiol derivative developed for the treatment of chronic obstructive bronchitis, including acute infective exacerbation of chronic bronchitis. Erdosteine contains 2 blocked sulfhydryl groups which are released following first-pass metabolism. The 3 active metabolites exhibit mucolytic and free radical scavenging activity. Erdosteine modulates mucus production and viscosity and increases mucociliary transport, thereby improving expectoration. It also exhibits inhibitory activity against the effects of free radicals produced by cigarette smoke. Clinical studies in patients with chronic obstructive lung disease have demonstrated the efficacy and tolerability of erdosteine. Erdosteine 300mg twice daily reduced cough (both frequency and severity) and sputum viscosity more quickly and more effectively than placebo and reduced the adhesivity of sputum more effectively than ambroxol 30mg twice daily. Co-administration of erdosteine and amoxicillin in patients with acute infective exacerbation of chronic bronchitis resulted in higher concentrations of the antibiotic in the sputum, leading to earlier and more pronounced amelioration of clinical symptoms compared with placebo. Erdosteine is associated with a low incidence of adverse events, most of which are gastrointestinal and generally mild.

Paroxetine is a potent and selective inhibitor of the neuronal reuptake of serotonin, thereby facilitating serotoninergic transmission; this action appears to account for the antidepressant activity observed with this drug. A mean terminal elimination half-life of approximately 24 hours permits once daily administration. Results of short term clinical trials have shown paroxetine to be significantly superior to placebo, and comparable to amitriptyline, clomipramine, imipramine, dothiepin and mianserin in relieving symptoms associated with major depressive disorders. Paroxetine has shown some preliminary promise in the treatment of depressive illness resistant to tricyclic antidepressant therapy but further studies are required before any conclusions can be drawn. Paroxetine in therapeutic doses has been very well tolerated, and the favourable tolerability profile of this agent appears to be its primary advantage over traditional antidepressant agents. Paroxetine causes minimal anticholinergic-type adverse effects, and unlike tricyclic antidepressants, it does not precipitate cardiovascular effects or provoke cardiac conduction disturbances. Nausea has been the most frequently reported adverse event during short term use of paroxetine, but it is generally mild and transient and subsides with continued use. With longer term use headache, sweating and constipation were the most frequently reported side effects but the incidence rate was not significantly different from that noted for comparator antidepressants. Furthermore, the frequency of withdrawal due to adverse effects is less with paroxetine than with tricyclic antidepressant agents. Overall, available data appear to indicate that while the efficacy of paroxetine is similar to that of traditional antidepressant drugs, the newer agent possesses much improved tolerability. In addition, the wide therapeutic index of paroxetine may be beneficial when treating patients with an increased risk of suicide. Thus, paroxetine clearly looks to become a valuable addition to the range of drugs currently available to treat depressive illness. Future research may help to further define the relative place of this newer agent in antidepressant therapy and determine how its overall therapeutic efficacy compares with that of other related antidepressant agents such as fluoxetine.

Ifosfamide is an oxazaphosphorine alkylating agent with a broad spectrum of antineoplastic activity. It is a prodrug metabolised in the liver by cytochrome P450 mixed-function oxidase enzymes to isofosforamide mustard, the active alkylating compound. Mesna, a uroprotective thiol agent, is routinely administered concomitantly with ifosfamide, and has almost eliminated ifosfamide-induced haemorrhagic cystitis and has reduced nephron toxicity. Therapeutic studies, mostly noncomparative in nature, have demonstrated the efficacy of ifosfamide/mesna alone, or more commonly as a component of combination regimens, in a variety of cancers. In patients with relapsed or refractory disseminated nonseminomatous testicular cancer, a salvage regimen of ifosfamide/mesna, cisplatin and either etoposide or vinblastine produced complete response in approximately one-quarter of patients. As a component of both induction and salvage chemotherapeutic regimens, ifosfamide/mesna has produced favourable response rates in small cell lung cancer, paediatric solid tumours, non-Hodgkin's and Hodgkin's lymphoma, and ovarian cancer. Induction therapy with ifosfamide/mesna-containing chemotherapeutic regimens has been encouraging in non-small cell lung cancer, adult soft-tissue sarcomas, and as neoadjuvant therapy in advanced cervical cancer. As salvage therapy, ifosfamide/mesna-containing combinations have a palliative role in advanced breast cancer and advanced cervical cancer. Ifosfamide/mesna can elicit responses in patients refractory to numerous other antineoplastic drugs, including cyclophosphamide. With administration of concomitant mesna to protect against ifosfamide-induced urotoxicity, the principal dose-limiting toxicity of ifosfamide is myelosuppression; leucopenia is generally more severe than thrombocytopenia. Reversible CNS adverse effects ranging from mild somnolence and confusion to severe encephalopathy and coma can occur in approximately 10 to 20% of patients after intravenous infusion, and the incidence of neurotoxicity may be increased to 50% after oral administration because of differences in the preferential route of metabolism between the 2 routes of administration. Other adverse effects of ifosfamide include nephrotoxicity, alopecia, and nausea/vomiting. In general, intravenously administered mesna is associated with a low incidence of adverse effects; however, gastrointestinal disturbances are common following oral administration. Thus, ifosfamide/mesna is an important and worthwhile addition to the currently available range of chemotherapeutic agents. It has a broad spectrum of antineoplastic activity and causes less marked myelosuppression than many other cytotoxic agents. At present, the role of ifosfamide/mesna in refractory germ cell testicular cancer is clearly defined; however, its overall place in the treatment of other forms of cancer awaits delineation in future well-controlled comparative studies.

Sumatriptan is a serotonin1 (5-HT1) receptor agonist, which is effective in the acute treatment of migraine headache. Its antimigraine activity is believed to derive from selective vasoconstriction of cranial blood vessels which are dilated and distended during migraine headache and/or from inhibition of neurogenically mediated inflammation in the dura mater. In placebo-controlled comparative studies, sumatriptan reduced migraine headache from 'moderate or severe' to 'mild or none' within 2 hours in 50 to 73% of patients following oral administration of 100 or 200 mg, and within 1 hour in 70 to 80% of patients following subcutaneous doses of 6 to 8 mg or intranasal doses 20 mg into each nostril. In addition, sumatriptan alleviated the accompanying symptoms of nausea, vomiting, and photophobia/phonophobia more effectively than placebo, and permitted higher percentages of patients to resume normal daily activities. Sumatriptan 100 mg orally was more effective in the acute treatment of migraine than oral combination therapy consisting of ergotamine 2 mg plus caffeine 200 mg or aspirin 900 mg plus metoclopramide 10 mg. Pooled data from nearly 5000 patients treated with either oral or subcutaneous sumatriptan in clinical trials indicate that it is well tolerated. However, migraine recurrence within 24 or 48 hours of initial symptom resolution developed in approximately 40% of patients treated with sumatriptan, irrespective of route of administration. It is likely that migraine recurrence is related to the short half-life of the drug (approximately 2 hours). Future studies should attempt to ascertain whether additional doses of sumatriptan will help prevent migraine recurrence in patients with attacks of long duration and if so, should determine the optimum interval between dosages. In conclusion, sumatriptan is an important addition to the range of drugs currently available for acute treatment of migraine. It provides rapid relief from debilitating symptoms in a high percentage of patients, particularly after subcutaneous administration. At this stage in its development a number of questions remain to be answered - most notably whether repeat doses will help prevent recurrent attacks and which patients are most likely to respond to therapy. Nevertheless, sumatriptan presently offers a combination of efficacy and tolerability that is unique in this particular clinical setting.

Levocabastine is a long acting, highly potent and selective histamine H1-receptor antagonist, which has been developed for nasal and ocular administration. In controlled trials performed to date levocabastine was effective and well tolerated in the treatment of allergic rhinitis and allergic conjunctivitis. Comparative studies have demonstrated that levocabastine is superior to placebo and at least as effective as sodium cromoglycate (cromolyn sodium) in alleviating symptoms associated with seasonal allergic conditions. Although levocabastine appears to be less effective than the topical corticosteroid beclomethasone with regard to relieving runny and blocked nose, further comparative trials between these 2 agents would be desirable. Similar to other antihistamines, levocabastine provides minimal relief of nasal blockage, but this symptom is believed to be mediated by receptors other than histamine H1. The prompt onset of antiallergic activity after application differentiates levocabastine from the reference topical antiallergic, sodium cromoglycate, which has an onset of efficacy characterised by a lag period, thereby necessitating maintenance treatment. The incidence of adverse effects associated with levocabastine therapy is low and is similar to that observed with placebo and sodium cromoglycate. Levocabastine provides prophylactic protection as well as acute relief from nasal and ocular symptoms in patients with seasonal allergic disorders. With the ever increasing trend towards topical therapy for the treatment of allergic rhinitis and allergic conjunctivitis, levocabastine is a useful addition to the range of drugs currently available. Possible avenues for additional research should include determining whether the antiallergic efficacy of topical levocabastine is superior to that of oral agents such as astemizole and terfenadine, and whether topical therapy is indeed preferred, considering the relative ease of administration of effective oral antiallergic agents.