Which of the following statement is true regarding fixed dose combination of drugs?

Fixed dose combination (FDC):- Combination of two or more active drugs in single dose form. Rationality of FDC's should be based on ceain aspect such as:- The drugs in combination should act by different mechanism. Pharmacokinetic must not be widely different. Combination should not have supraadditive toxicity of the ingredients. Demerits:- Dosage alteration of one drug is not possible without alteration of other drugs. Differing pharmacokinetic of constituent drugs poses the problem of frequency of administration of the formula. Increased chance of adverse drug effect and interaction compared with both drugs given individually.