Calcium antagonists hypotension caused

Calcium antagonists can cause serious toxicity or death with relatively small overdoses. These channel blockers depress sinus node automaticity and slow AV node conduction (see Chapter 12). They also reduce cardiac output and blood pressure. Serious hypotension is mainly seen with nifedipine and related dihydropyridines, but in severe overdose all of the listed cardiovascular effects can occur with any of the calcium channel blockers. 

The double whammy—additive detrimental effects and novel adverse reactions Combination therapy takes advantage of synergistic mechanisms of antihypertensive action, but this can also be detrimental, particularly if patients are over-treated, leading to dizziness and orthostatic hypotension. Additive effects of certain combinations can also exacerbate adverse reactions that are common with individual agents. For example, calcium channel blockers and alpha-adrenoceptor antagonists both cause peripheral edema, which can be severe if these agents are used together. 

Many different drug classes have shown to cause hypotension and orthostatic reactions and drugs for cardiovascular conditions, psychoactive medicines and polypharmacy, can all have this side effect (Box 5.15). Among the most frequently used drugs in the elderly are diuretics, ACE-inhibitors, angiotensin II antagonists, calcium channel blockers and antidepressants. 

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