The effects of drug interactions are as follows:
1.The mechanism by which the pharmacodynamic effects of drug interactions add up or increase their efficacy is as follows:
1) Acting on different target sites, producing synergistic effect.
2) Protect the drug from destruction, thereby increasing the efficacy.
3) Promote absorption and increase efficacy.
4) Delay or reduce drug resistance to increase efficacy.
2.Drug interactions, acting on different target sites, resulting in synergistic effects, for example:
1) Sulfamethoxazole and trimethoprim have synergistic antibacterial or bactericidal effects. Sulfamethoxazole and trimethoprim act on dihydrofolate synthase and dihydrofolate reductase respectively, so that the folate metabolism of bacteria is double blocked.
2) The combination of atropine sulfate and cholinesterase reactivator produces complementary effect, which can reduce the dosage of atropine and adverse reactions, and improve the therapeutic effect of organophosphorus poisoning.
3) Methoxyclopramide and magnesium sulfate have synergistic cholagogic effect.
4) The sedative effect of metoclopramide combined with central depressants was enhanced.
5) The combination of propranolol and methilol has a synergistic effect on ventricular premature beats and ventricular tachycardia, but the dosage should be reduced when combined.
3.Drug interactions to protect the drug from destruction, thereby increasing its efficacy. Examples:
1) Adding cisastatin sodium to imipenem preparation, because imipenem can be destroyed by renal peptidase in the kidney, and cisastatin sodium is a renal peptidase inhibitor, it can protect imipenem from being destroyed in the kidney, block the metabolism of imipenem in the kidney, and ensure the effectiveness of the drug.
2) β -lactamase inhibitors and β -lactamase antibiotic compound preparation, because β -lactamase inhibitors can compete and non-competitively inhibit β -lactamase, penicillin, cephalosporins are protected from ring opening damage.
3) When benserazid or carbidopa is combined with levodopa, benserazid/carbidopa is an aromatic amino acid dehydroxylase inhibitor, which can inhibit the process of decarboxylation of levodopa to dopamine in the periphery. As the levodopa content in the circulation increases 5-10 times, the amount of dopamine entering the brain also increases. When the two drugs are used together, the blood concentration of levodopa can be increased, the amount of levodopa entering brain tissue can be increased, its half-life can be prolonged, and the dosage of levodopa can be reduced, and the adverse reactions of peripheral cardiovascular system can be reduced.
4.Drug interactions to delay or reduce drug resistance in order to increase efficacy. For example:
1) The antimalarial drug artemisinin can induce resistance, and when used in combination with pyrazine and sulfamedoxine, it can delay the development of resistance.
2) The combined application of fosfomycin with β -lactam, aminoglycosides, macrolides and fluoroquinolones has additive or synergistic effects, and reduces the generation of drug-resistant strains.
5.Drug interactions to reduce adverse drug reactions. Examples:
1) Atropine combined with morphine can alleviate the smooth muscle spasm caused by the latter and strengthen the analgesic effect.
2) Propranolol and nitrate have synergistic effect on anti-angina pectoris, and offset or reduce their respective adverse reactions.
3) Propranolol combined with nifedipine can improve the effect of blood pressure, and has a good effect on labor and unstable angina pectoris.
4) The combination of propranolol and atropine can eliminate the bradycardia caused by propranolol and tachycardia caused by atropine.
6.Drug interactions and sensitization, for example:
1) potassium diuretics can reduce plasma potassium ion concentration, so that the heart is sensitive to cardioside drugs, prone to arrhythmia.
2) After the application of reserpine or guanetridine, the adrenergic receptor can be induced to undergo similar neuropathic hypersensitivity phenomenon, thus enhancing the pressor effect of adrenergic drugs with direct effect.
7.Drug interactions that affect absorption, for example:
1) When compound antacids are taken together with tetracycline, because compound antacids usually contain Ca2+, Mg2+, Al3+ and Bi3+, they can form insoluble coordination compounds (complexes), which is not conducive to absorption and affects the efficacy.
2) atropine, belladonia, propylene amine too Lin, can delay gastric emptying, increase the absorption of drugs.
3) Methoclopramide and domperidone can increase intestinal peristalsis, thereby reducing the retention time of drugs in the intestinal tract and affecting the absorption of drugs.
8.The important factors affecting drug distribution include: the binding rate of drug to plasma protein is an important factor affecting drug distribution in vivo