First Generation 3-Blockers

Current data suggest little benefit on clinical outcomes beyond symptom relief for calcium channel blockers in the setting of ACS.43 Moreover, the use of first-generation shortacting dihydropyridines, such as nifedipine, should be avoided because they appear to worsen outcomes through their negative inotropic effects, induction of reflex sympathetic activation, tachycardia, and increased myocardial ischemia.43 Therefore, calcium channel blockers should be avoided in the acute management of MI unless there is a clear symptomatic need or a contraindication to p-blockers. 

Adverse effects and contraindications of calcium channel blockers are described in Table 5-2. Verapamil, diltiazem, and first-generation dihydropyridines should also be avoided in patients with acute decompensated heart failure or left... 

Many of these drugs have effects that are not mediated by Hi-receptors (Table 38.2). The antimuscarinic activity of several first-generation Hj-blockers may account for their effectiveness in combating motion sickness and their limited ability to suppress parkinsonian symptoms. The phenothiazines have some capacity to block a-adrenoceptors, whereas cyproheptadine Periactin) is an antagonist at serotonin receptors. Diphenhydramine Benadryl), pyrilamine (Ryna), and promethazine Phen-ergan) are effective local anesthetics. Many second-generation antihistamines also have been found to inhibit the non-histamine-mediated release of various... 

The first generation Hi blockers (including diphenhydramine and hydroxyzine) cross the blood-brain barrier. Subsequent generations of antihistamines have been developed so that they do not cross the blood-brain barrier, and therefore are not effective as sedatives or anxiolytics. 

First-generation H -receptor blockers are among the most extensively promoted and used over-the-counter drugs. The prevalence of allergic conditions and the relative safety of the drugs contribute to this heavy use. The fact that they do cause sedation contributes to heavy prescribing of second-generation antihistamines. 

Other first-generation H1 blockers Chlorpheniramine is a less sedating Hi blocker with fewer autonomic effects... 

The first generation antipsychotics, now known as typical drugs, were all D2 receptor blockers and, as such, very likely to produce Parkinsonian side effects. Because antipsychotic potency was associated with D2 receptor affinity, it was assumed that dopamine overactivity was the essential defect in schizophrenia and that a direct dopamine blockade was the definitive route to treatment. But these drugs affected both the target dopamine pathways of the mesolimbic projection and the uninvolved nigrostriatal projection. Unfortunately, that meant that movement disorders were the price that had to be paid for antipsychosis. 

Dihydropyridines This rapidly expanding class of calcium channel blockers includes the first-generation nifedipine [nye FED i peen],... 

The term antihistamine, without a modifying adjective, refers to the classic Hi receptor blockers. These compounds do not influence the formation or release of histamine, but rather they competitively block the receptor-mediated response of a target tissue. [Note This contrasts with the action of cromolyn (see p. 220), which inhibits the release of histamine from mast cells and is useful in the treatment of asthma.] The H receptor blockers can be divided into first- and second generation drugs.(Figure 40.5). The first generation drugs are still widely used because they are effective and inexpensive. 

Some adverse effect observed with first generation Hr-histamine blockers. 

The first generation of a-adrenoceptor blockers were nonselective, blocking both Oj- and o -receptors. When subjects taking such a drug rise from supine to erect posture or take exercise, the sjmipathetic system is physiologically activated (via baroreceptors). The normal vasoconstrictive (a,) effect (to maintain blood pressure) is blocked by the drug and the failure of this response causes the sympathetic system to be further activated and to release more and more transmitter. This increase in transmitter would normally be reduced by negative feedback via the a -autoreceptors but these are blocked too. 

Low molecular weight heparins Extended spectmm penicillins First-generation cephalosporins Second-generation cephalosporins Third-generation cephalosporins Proton pump inhibitors blockers 5HT3 inhibitors Fluroquinolones Oxazolidinones/streptagramins Parenteral amino acids Sedative hypnotics Enteral feedings Insulins... 

Adverse effects and contraindications of calcium channel blockers are described in Table 16. Verapamil, diltiazem, and first-generation dihydropyridines also should be avoided in patients with acute decompensated heart failure or LV dysfunction because they can worsen heart failure and potentially increase mortality secondary to their negative inotropic effects. In patients with heart failure requiring treatment with a calcium channel blocker, amlodipine is the preferred agent. ... 

First generation P-blockers are non-cardio-selective and they can produce bronchocon-striction as an adverse effect. They exacerbate congestive heart failure, adversely affect plasma lipid profiles and reduce exercise tolerance. An example is propranolol. 

Antihistamine first generation H, blocker prototype Tox mild sedation, little antimuscarinic action. 

The most potent drug substanee belonging to the first generation P-blockers, propranolol, shall be diseussed here under ... 

It has been stated earlier that the first generation and the second generation P-blockers essentially possess either isopropyl or tertiary-huiyX functional moieties attached to the N-alkyl groups. 

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