Mefloquine is an orally administered blood schizontocide. Initial dose-finding and comparative studies performed between 1977 and 1989 demonstrated efficacy of mefloquine as prophylaxis in nonimmune individuals and in the suppression and treatment of malaria in adults and children caused by multidrug-resistant Plasmodium falciparum. It was also effective against P. vivax infection, while data concerning the treatment of P. ovale and P. malariae infections were limited. In an attempt to delay the emergence of resistance to this promising antimalarial agent, mefloquine was combined with sulfadoxine and pyrimethamine. Although initial clinical trials indicated that this regimen was effective in preventing and treating falciparum malaria, recent treatment failures, the potential for severe dermatological reactions and lack of therapeutic advantage over mefloquine alone has prompted the World Health Organization to recommended that the combination be no longer used for treatment or prophylaxis of malaria. Mefloquine is generally well tolerated in both adults and children, with nausea, vomiting, diarrhoea, headache, dizziness, rash, pruritus and abdominal pain being the most common adverse effects, although it is difficult to distinguish between disease- and treatment-related events. The incidence of these adverse effects is similar to or lower than those observed with other antimalarial agents. Cardiovascular changes, such as bradycardia, occasionally occur. The most notable adverse effects associated with mefloquine are neuropsychiatric disturbances; precipitation of such events should be closely monitored and requires termination of prophylaxis or therapy. The eventual emergence of resistance to mefloquine, as with many other antimalarial agents, was inevitable. Mefloquine resistance is established in certain areas of Thailand and may be becoming a growing problem in other regions of the world. In order to preserve the efficacy of mefloquine in non-resistant areas, this useful agent should be used with care and only prescribed for prophylaxis in travellers and treatment in areas of multidrug-resistant plasmodia. Future options to combat mefloquine resistance may include the combination of mefloquine with other antimalarial agents such as qinghaosu derivatives. Thus, with cautious use and possible combination with other agents, mefloquine is likely to remain an important treatment option for falciparum malaria, a widespread parasitic disease for which an increasing number of drugs have proved inadequate.

Venlafaxine is a phenylethylamine derivative which facilitates neurotransmission in the brain by blocking presynaptic reuptake of serotonin (5-hydroxytryptamine: 5-HT) and noradrenaline (norepinephrine). Clinical data from patients with major depression are consistent with the favourable efficacy and tolerability profile of venlafaxine predicted by pharmacodynamic studies. In patients with major depression, venlafaxine 75 to 375 mg/day administered for 6 weeks was significantly more effective than placebo, and at least as effective as imipramine, clomipramine, trazodone or fluoxetine. Venlafaxine is well tolerated, being associated with fewer anticholinergic and CNS adverse effects than tricyclic antidepressants. Unlike the tricyclic antidepressants, venlafaxine does not appear to significantly affect cardiac conduction, although there have been a few reports of modest increases in blood pressure, particularly after high doses of the drug. In conclusion, wider clinical experience is required to better characterise and confirm potential advantages of venlafaxine compared with other antidepressant agents. These advantages may include a rapid onset of action and reduced propensity to cause anticholinergic effects and cardiotoxicity compared with tricyclic antidepressants. Nevertheless, at this stage venlafaxine offers a more attractive treatment option than tricyclic antidepressants for patients with major depression, primarily because of its good overall tolerability profile.

Fluticasone propionate is an androstane carbothioate glucocorticosteroid with almost twice the topical anti-inflammatory potency of beclomethasone dipropionate. Importantly, it is not appreciably absorbed from the gastrointestinal tract. However, the fraction of active drug absorbed from the lungs after inhalation, and therefore total systemic availability, has yet to be determined. Inhaled fluticasone propionate administered at dosages of 1500 micrograms/day for 1 year or 2000 micrograms/day for 6 weeks did not cause clinically significant pituitary-adrenal suppression. Preliminary data from 2 published trials also indicate no significant effect on growth in children. However, wider clinical experience is needed to clarify the effects of long term administration on pituitary-adrenal function, bone metabolism and attainment of adult height in children. In clinical studies, inhaled fluticasone propionate was at least as effective as beclomethasone dipropionate or budesonide when administered at half the dosage of the comparators in patients with mild to moderate or severe asthma. Limited data suggest that fluticasone propionate also has considerable potential in the management of childhood asthma. In trials of up to 1 year in duration, fluticasone propionate appeared to be well tolerated by both adults and children. Whether an improved tolerability profile compared with other corticosteroids is a major clinical benefit of the extremely low oral bioavailability of inhaled fluticasone propionate requires confirmation. Nevertheless, on the basis of available data from initial clinical trials of mostly limited duration, inhaled fluticasone propionate offers an effective treatment option for the management of asthma, with the potential of an enhanced safety profile.

Worldwide, hepatitis B virus (HBV) infection is a major cause of acute and chronic hepatitis, cirrhosis and hepatocellular cancer. Infants and children are at the greatest risk of becoming chronically infected with HBV, and therefore at the greatest risk of developing long term sequelae. Immunisation against HBV represents an important means of controlling the disease. Hepatitis B vaccines are effective in preventing HBV infection and are well tolerated. In addition, they are suitable for integration into mass neonatal vaccination programmes. While there are considerable economic data concerning hepatitis B vaccination, differing methodologies and end-points present a challenge in reviewing these studies for consistent findings. Immunisation strategies should be implemented in accordance with local area disease incidence and patterns of HBV transmission, and will be influenced by regional budgetary constraints. In conclusion, universal neonatal vaccination is both cost effective and appropriate for control of HBV infection in regions of medium or high endemicity. In low endemicity areas, selective vaccination of high-risk groups is cost effective, but its impact on the incidence of HBV infection will depend on the ability to reach these groups. Expanded vaccination strategies may be appropriate where local conditions prohibit efficient access to high-risk groups.

The presumed but as yet unspecified autoimmune-mediated basis for the pathogenesis of multiple sclerosis has led to attempts to modify the immune system of patients with this disease based on general and selective approaches. The rationale for using interferon-beta for the treatment of multiple sclerosis is based on its antiviral and complex immunoregulatory activities. Interferon-beta-1a (Avonex(R)) is a recombinant molecule which is indistinguishable from natural interferon-beta derived from human fibroblasts. Its precise mechanism of action is unknown, although effects on immune system processes which have been implicated in the pathogenesis of multiple sclerosis have been documented. T cell activation and migration into the CNS is a primary process in the pathogenesis of multiple sclerosis. In vitro and in vivo, interferon-beta-1a, compared with placebo or no treatment, significantly reduced expression of T cell surface activation markers, and significantly increased CNS levels of interleukin-10 - a potent inhibitor of cell-mediated immune responses. Pharmacokinetic studies indicate that intramuscular injection is the optimal route of administration for this formulation of interferon-beta-1a. In patients with relapsing-remitting multiple sclerosis who participated in a randomised double-blind trial, interferon-beta-1a 30mug (6 MIU) administered by intramuscular injection once weekly for 2 years (n = 158), compared with placebo (n = 143), significantly extended the time to onset of sustained neurological disability. Interferon-beta-1a also reduced the rate of disease relapse by approximately one-third compared with placebo, a finding which was supported by cranial magnetic resonance imaging (MRI) data showing significant reductions in lesion number and volume. Interferon-beta-1a was well tolerated, with influenza-like symptoms making up the majority of adverse reactions. The clinical significance of the beneficial effect of interferon-beta-1a on disease progression has been endorsed by the findings of a retrospective statistical analysis of the disability outcomes data obtained in the double-blind trial. In patients with relapsing multiple sclerosis, interferon-beta-1a is the only drug that has been demonstrated to significantly slow disease progression without excessive toxicity, in addition to significantly reducing the rate of relapse - measured clinically and by MRI. Notwithstanding the absence of long term tolerability data, and data from comparative trials with other agents, interferon-beta-1a represents a promising advance in drug therapy for relapsing multiple sclerosis.