Interactions, drug synergistic

Combining midazolam and alfentanil or fentanyl for the induction of anaesthesia reduces the dose required of both the benzodiazepine and the opioid, when compared with either drug alone.The interaction is synergistic. ... 

Mitochondria-associated toxicities, such as pancreatitis, are frequently demonstrated in HlV/HCV-coinfected individuals, and may significantly influence treatment options (de Mendoza and Soriano 2005). Yet, no cell culture or animal models have been developed to predict nucleoside-induced pancreatitis. Nevertheless, an association of HCV replication and mitochondrial DNA depletion in primary human lymphocytes obtained from HIV/HCV-coinfected individuals under concomitant administration of HCV and HIV medications was demonstrated by de Mendoza and coworkers (de Mendoza et al. 2007). They claimed that the use of HCV medication together with certain antiretroviral agents seemed to enhance mitochondrial damage due to a synergistic deleterious interaction between the anti-HCV and anti-HIV drugs. In contrast, an improvement in mitochondrial content with effective... 

Pertwee RG, Ross TM. (1991). Drugs which stimulate or facilitate central cholinergic transmission interact synergistically with delta-9-tetrahydrocannabinol to produce marked catalepsy in mice. Neuropharmacology. 30(1) 67-71. 

Pretreatment of human T24 bladder or human colorectal adenocarcinoma cells with 5-FU followed by CGP 41251 showed a synergistic drug interaction in both cell lines (Fabbro et al., 1999). CGP 41251 or 5rFU were ineffective as a single agent against COLO 205 tumors up to 200 mg/kg/day p.o. and 75 mg/kg/week i. v., respectively. Combination of both compounds at these concentrations showed significant antitumor activity in this tumor model (Fabbro et al., 1999). 

Pharmacodynamic interactions generally involve additive, synergistic or antagonistic effects of drugs acting on the same receptors or physiological systems. These interactions are more difficult to classify than those with a pharmacokinetic basis. They are fairly common but may not always be recognised. 

Propofol is primarily a hypnotic drug with substantial cardiorespiratory depressant actions and with no ability to produce neuromuscular blockade. While propofol lacks analgesic properties, its use permits lower doses of opioids. Likewise, less propofol is required for adequate hypnosis when it is administered with opioids. Thus, it is said that propofol and opioids interact synergistically. 

Pharmacodynamic interactions take place at the site of drug action. When two or more drugs with similar pharmacological effects are administered together, an additive or synergistic effect is usually seen. 

However, the information derived from a detailed pharmacokinetic study will help to anticipate potential botanical product-drug interactions, to optimize the bioavailability, the quality, and hence the efficacy of herbal medicines, to support evidence for the synergistic nature of herbal medicines, and to better appreciate the safety and toxicity of the plant. Because pharmacokinetic studies with herbal medicines are often complicated by their chemical complexity and by the fact that the active compounds are often unknown, it could be one future issue to assess bioavailability by measuring surrogate parameters in plasma or tissue instead of directly assaying putative active compounds in the blood. In summary, to use HMPs in an evidence-based approach and to achieve the status rational phytomedicine, more experimental studies are needed to characterize the bioavailability and pharmacokinetics of botanical products. 

Synergy studies are in vitro tests that attempt to measure synergistic, additive, indifferent, or antagonistic drug interactions. In general, these tests have not been standardized and have not correlated well with clinical outcome. (See section on Antimicrobial Drug Combinations for details.)... 

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