A Study to Evaluate the Effect of GW870086X on Allergen Challenge in Mild Asthmatics

Inclusion Criteria

• Male subjects between 18 and 65 years of age inclusive.
• Male subjects must agree to use one of the contraception methods listed in Section 8. This criterion must be followed from the time of the first dose of study medication until 90-95 hours post-last dose.
• BMI within the range 19.0 - 29.0 kg/m2 (inclusive).
• Liver function tests (bilirubin, AST, ALT) within normal laboratory parameters at screening.
• Documented history of bronchial asthma, first diagnosed at least 6 months prior to the screening visit and currently being treated only with intermittent short-acting beta -agonist therapy by inhalation.
• Pre-bronchodilator FEV1 >65% of predicted at screening.
• No history of smoking within 6 months of the start of the study, and with a total pack year history of = 3 mm relative to negative control) to at least one allergen from a battery of allergens (including but not limited to house dust mite, grass pollen, cat dander, hazel, horse and birch) on skin prick testing at screening, or within 12 months of study start.
• Screening allergen challenge demonstrates that the subject experiences both an early and late asthmatic response. The early asthmatic response must include a fall in FEV1 of >= 20% from the post saline value, on at least one occasion, between 5 and 30 minutes after the final concentration of allergen. The late asthmatic response must include a fall in FEV1 of >= 15% from the post saline value, on at least three occasions, two of which must be consecutive, between 4 and 10 hours after the final concentration of allergen.
• Reproducible allergen challenge at screening (confirmation of the dose ascending allergen challenge by a bolus allergen challenge at least 14 days later).
• Sensitivity to methacholine with a provocative concentration of methacholine resulting in a 20% fall in FEV1 (PC20 methacholine) of 140mmHg or diastolic BP > 90mmHg.
• Respiratory tract infection and/or exacerbation of asthma within 4 weeks prior to the first dose of study medication.
• History of life-threatening asthma, defined as an asthma episode that required intubation and/or was associated with hypercapnoea, respiratory arrest and/or hypoxic seizures.
• Administration of oral, injectable or dermal steroids within 4 weeks or intranasal and/or inhaled steroids within 2 week of the screening visit.
• The subject has a positive pre-study drug/alcohol screen. A minimum list of drugs that will be screened for include amphetamines, barbiturates, cocaine, opiates, cannabinoids and benzodiazepines.
• A positive pre-study Hepatitis B surface antigen or positive Hepatitis C antibody result within 3 months of screening.
• A positive test for HIV antibody.
• History of regular alcohol consumption within 6 months of the study defined as:

an average weekly intake of greater than 21 units or an average daily intake of greater than 3 units (males). One unit is equivalent to a half-pint (220mL) of beer or 1 (25ml) measure of spirits or 1 glass (125ml) of wine.

• The subject has participated in a clinical trial and has received an investigational product within the following time period prior to the first dosing day in the current study: 30 days, 5 half-lives or twice the duration of the biological effect of the investigational product (whichever is longer).
• Exposure to more than four new chemical entities within 12 months prior to the first dosing day.
• Use of prescription or non-prescription drugs, including vitamins, herbal and dietary supplements (including St John's Wort) within 7 days (or 14 days if the drug is a potential enzyme inducer) or 5 half-lives (whichever is longer) prior to the first dose of study medication, unless in the opinion of the Investigator and GSK Medical Monitor the medication will not interfere with the study procedures or compromise subject safety. Paracetamol is an exception and will be permitted at daily doses of up to 4 g from screening to follow-up.
• Has taken Xanthines (including th