How Does Spiriva (Tiotropium) Work? Mechanism of Action Reviewed.

A reader asked me this question:
How does Spiriva work (what does it do)? I read the stuff on it, but my eyes glazed over. Can you put the cookies on the bottom shelf for this lay person?
Well reader, here's your answer:  
Spiriva, or Tiotropium, competitively and reversibly inhibits the action of acetylcholine at type 3 muscarinic (M3) receptors in bronchial smooth muscle causing bronchodilation. 
If you have any other questions, just let me know.  Just kidding.  In lay persons terms there are several ways to intervene in the treatment of asthma or COPD.  The goal is to  open up the airways leading from your mouth to your lung tissue and to reduce the amount of inflammation that can cause airways to spasms and shut down.  Many pulmonary medications keep airways open and free of inflammation to allow easy passage of oxygen in and carbon dioxide out.  The steroids help cut down inflammation which can reduce their propensity to spasm.   Smoking is an irritant and makes them spasm all the time.  Steroids are  often given intravenously in the hospital setting in very high doses and orally and orally or inhaled on a long term outpatient basis. 

Several classes of drugs can help open up the airways. They are called bronchodilators.  One class works on the beta-2 specific smooth muscle receptors in the airways to cause them to dilate (short acting albuterol and long acting salmeterol (Serevent) or long acting formoterol (Foradil).  The other class works on acetylcholine receptors to cause bronchodilation (short acting ipratropium or long acting Spiriva).  Both drugs attack the same problem from a different mechanism in order to open up the airway.   These drugs are often put in combination with each other:
  • Duoneb nebulizer (albuterol (Ventolin) + ipratropium (Atrovent))
  • Combivent (duoneb in inhaler form)
  • Advair (Salmeterol + fluticasone steroid) long acting agent
  • Symbicort (formoterol + budesonide steroid) long acting agent
  • Tiotropium (Spiriva) long acting agent
These newer long acting drugs are expensive.  Hospitalized patients will often get started on them and then told to continue with them on discharge.  Unfortunately, many of these newer long acting agents can run upwards of $150 or more per month.  Are they better than the generic short acting agents?  Do they offer any addition protection other than convenience on a cost axis?  I don't know.  I haven't reviewed the literature for quite some time.  I do know they can be difficult to approve on some formularies and many patients have difficulty paying for them.  And for many folks, the best treatment is to quit smoking, not to spend hundreds of dollars on expensive inhalers.  

The thing that I really think is silly  is that many patients come into the hospital on $500 more more worth of these inhalers a month while smoking one, two or three packs of cigarettes a day. For my smokers with heart disease, I  tell them we could throw every medicine known to benefit man at them,  from aspirin, ACEi, b-blockers, statins and Plavix, but if they continue to smoke, they are wasting their money.  They  might as well write a check to Uncle Sam to pay down the deficit instead of going to Walmart every month to pick up their medications.  At least they would save some gas money.

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