The progestogen dienogest exhibits highly selective binding to the progesterone receptor. It has high progestational and significant antiandrogenic activity, but only moderate antigonadotrophic activity. Dienogest inhibits ovulation, produces secretory transformation of the endometrium and has antiproliferative effects. Oral dienogest 2 mg/day plus ethinylestradiol 30 micrograms/day provides effective contraception (Pearl Index approximately 0.2). Cycle stability is good during long term use of this combination; irregular vaginal bleeding was evident in 6% of women after 12 months' use. Androgenic symptoms (including hirsutism, seborrhoea, alopecia, acne vulgaris and hair and skin greasiness) improved in women treated with dienogest plus ethinylestradiol. The adverse events associated with dienogest are typical of those expected of a progestogen. The drug does not produce androgenic adverse effects and has little clinically significant effect on metabolic, lipid and haemostatic parameters.

1080 Stiderberg M, Lundgren R, Angstrom T. Effect of cetirizine on histamine-induced bronchoconstriction and bronchoalveolar cells. Allergy 46: 217-221,1991 Spyropoulou-Vlahou M, Stavropoulos-Giokas A, Filippou M, Koyas A, Kontou-Fili K. Clinical and laboratory results confirm the efficacy of cetirizine 2HCI in seasonal allergic rhinitis. Acta Therapeutica 16: 71-78, 1990 Tashkin DP, Brik A, Gong Jr H. Cetirizine inhibition of histamineinduced bronchospasm. Annals of Allergy 59 (Part II): 49-52, 1987 Tjwa MKT, Widjaja P, DelBono L, Pichler WJ, Backhouse CI, et al. Loratadine compared to cetirizine in patients with seasonal allergic rhinitis. Abstract. Allergy 47 (Suppl.): 174, 1992 van Neste D, Coussement C, Ghys L, Rihoux J-P. Agonist-antagonist interactions in the skin: comparison of effects of loratadine and cetirizine on skin vascular responses to prick tests with histamine and substances P. Journal of Dermatological Science 4: 172-179, 1992 Varney V, Gaga M, Frew AJ, De Vos C, Kay AB. The effect of a single oral dose of prednisolone or cetirizine on inflammatory cells infiltrating allergen-induced cutaneous late-phase reactions in atopic subjects.

Rhein, the active metabolite of diacerein, inhibits interleukin-1 activity. Consequently, collagenase production in articular cartilage is reduced. Rhein dose-dependently inhibits superoxide anion production, chemotaxis and phagocytic activity of neutrophils, and macrophage migration and phagocytosis. Articular cartilage damage is reduced by diacerein in animal models of osteoarthritis. Diacerein does not alter renal or platelet cyclooxygenase activity and may therefore be tolerated by patients with prostaglandin-dependent renal function. In clinical trials of < or = 6 months' duration, oral diacerein 50mg twice daily was associated with improvement in 57 to 85% of patients with osteoarthritis. Pain scores and measures of joint function were generally reduced compared with baseline and placebo. Diacerein had similar efficacy to NSAIDs, but a slower onset of action, in comparative trials of < or = 2 months' duration conducted in patients with osteoarthritis. The predominant adverse effects of diacerein are diarrhoea and related disorders.

Dorzolamide (dorzolamide hydrochloride), the first topical carbonic anhydrase (CA) inhibitor to become available for clinical use, lowers intraocular pressure (IOP) by reducing aqueous humour formation. It is formulated as a 2% eyedrop for use in the management of glaucoma and ocular hypertension. When administered 3 times daily, dorzolamide is effective in lowering IOP in patients with open-angle glaucoma or ocular hypertension. Mean IOP was reduced by approximately 4 to 6 mm Hg at peak (2 hours postdose) and 3 to 4.5 mm Hg at trough (8 hours postdose) in clinical trails. A 1-year comparative study showed that the ocular hypotensive efficacy of dorzolamine 2% 3 times daily was similar to that of betaxolol 0.5% twice daily, but slightly inferior to that of timolol 0.5% twice daily. Dorzolamide has additive ocular hypotensive effects when used in conjunction with topical beta-adrenergic antagonists and was as effective as pilocarpine 2% 4 times daily as adjunctive therapy in patients receiving timolol. Dorzolamide does not appear to produce the acid-base or electrolyte disturbances and severe systemic adverse events associated with oral CA inhibitors, and unlike beta-adrenergic antagonists, it is not contraindicated in patients with asthma, reactive airways disease or heart disease. Furthermore, as CA inhibitors do not cause miosis, they may cause less interference with vision than pilocarpine or epinephrine (adrenaline). The most common adverse effects associated with dorzolamide are bitter taste and transient local burning or stinging. Conjunctivitis was the most common reason for discontinuation of dorzolamide in one large study. Thus, available data suggest that dorzolamide has potential as an alternative therapy option in patients with glaucoma or ocular hypertension who are intolerant of, or unable to receive, ophthalmic beta-adrenergic antagonists and as adjunctive therapy in patients already receiving these agents. Further efficacy and tolerability data are needed to determine the place of dorzolamide in therapy.

The use of ondansetron, a selective serotonin 5-HT3 receptor antagonist, is well established in patients with nausea and vomiting associated with cancer chemotherapy, radiotherapy or anaesthesia and surgery. The wide distribution of 5-HT3 receptors in the body and the role of these receptors in disease have provided the rationale for investigation of ondansetron in novel applications. Preliminary data have shown ondansetron to have clinical benefit in patients with nausea and vomiting associated with drug overdosage or poisoning, anti-infective or antidepressant therapies, uraemia or neurological trauma, and in patients with pruritus. Patients with gastrointestinal motility disorders (e.g. carcinoid syndrome, irritable bowel syndrome, diarrhoea associated with cryptosporidiosis or diabetes, and chronic refractory diarrhoea) have also shown some improvement when treated with ondansetron, as have patients with certain pain or CNS-related disorders [e.g. alcohol (ethanol) dependence, opiate withdrawal, vertigo, cerebellar tremor and Parkinson's disease treatment-related psychosis]. In contrast to conventional antiemetics, ondansetron is generally well tolerated with a lower incidence of sedation and only isolated case reports of extrapyramidal reactions. Furthermore, unlike dopamine receptor-blocking neuroleptics, ondansetron does not appear to worsen the symptoms of Parkinson's disease. Thus, in addition to its established indications, preliminary results suggest that ondansetron may be beneficial in a number of novel applications. This drug may represent a treatment alternative in patients with refractory disease, or an effective treatment of conditions for which current therapies are either poorly tolerated or not available. Further investigation of ondansetron in a range of potential new applications appears to be warranted.