Why do you think aspirin is contraindicated in people with allergic asthma?

Aspirin irreversibly blocks both COX1 and COX2, thus more arachidonic acid is available to produce leukotrienes. Thus more leukotrienes can be produced which leads to bronchoconstriction that has a negative effect on asthmatic patients. 

Arachidonic acid is the most important precursor of the eicosanoids, but how is this fatty acid released from the cell membrane, and by which stimuli?

Arachidonic acid must first be released from membrane phospholipids for eicosanoid synthesis to occur. 

There are three classes of phospholipases that contribute to the release of arachidonic acid from membrane phospholipids:

• cytosolic PLA ₂
• secretory PLA₂
• calcium independent PLA₂

Apart from prostanoids and leukotrienes, which other non-eicosanoid product of cell membrane hydrolysis is strongly involved in asthma?

Why would you say a COX II-inhibitor, and not a COX I-inhibitor, has a selective action in inflammatory reactions?

• COX1: "house-keeping" functions
• COX2: it is common in the kidney and it's release is due to inflammation, shear-stress and growth factors. 

A drug that inhibits each of the following enzymes: phospholipase A; cyclooxygenase; lipoxygenase,

• phospholipase A: hydrocortisone
• cyclooxygenase: Aspirin
• lipooxygenase: zileuton

A drug that can act antagonistically or agonistically at prostaglandin and leukotriene receptors.

• misoprostil

Aspirin inhibits platelet aggregation because it inhibits thromboxane synthesis and not prostacyclin synthesis.  How does it happen?

It happens because it irreversibly blocks COX1 and COX2

How is alprostadil advantageous in the treatment of congenital heart defects?

It is given to patients to keep their hert valves open during surgery.

How is misoprostil of value in the treatment and prevention of gastric ulcers?

It protects the gastric lining

Prostaglandin is possible of value in asthma.  Which PG_E2- or PGF_2A-analogues will be effective in such a case?

Epoprostal

How is latanoprost of value in the treatment of glaucoma?

It increases the outflow of aqueous humor