The principal plasma proteins for drug binding are:
albumin
α1-acid glycoprotein
lipoproteinsSome drug interactions with warfarin are due to changes in protein binding. Cytochrome P450
Patients have abnormal metabolism by cytochrome P450 due to either inheriting abnormal alleles or due to drug interactions. Tables are available to check for drug interactions due to P450 interactions. Synergistic effects
An example of synergism is two drugs that both prolong the QT interval. Assessing causality
Causality assessment is used to determine the likelihood that a drug caused a suspected ADR. There are a number of different methods used to judge causation, including the Naranjo algorithm, the Venulet algorithm and the WHO causality term assessment criteria. Each have pros and cons associated with their use and most require some level of expert judgement to apply. An ADR should not be labeled as certain unless the ADR abates with a challenge-dechallenge-rechallenge protocol (stopping and starting the agent in question). The chronology of the onset of the suspected ADR is important, as another substance or factor may be implicated as a cause; co-prescribed medications and underlying psychiatric conditions may be factors in the ADR.Assigning causality to a specific agent often proves difficult, unless the event is found during a clinical study or large databases are used. Both methods have difficulties and can be fraught with error. Even in clinical studies some ADRs may be missed as large numbers of test individuals are required to find that adverse drug reaction. Psychiatric ADRs are often missed as they are grouped together in the questionnaires used to assess the population.
Severe renal colic caused by kinking ureter. Pain classically relieved a little by going on all fours with hips higher than head. Diagnosis
LPHS is considered a diagnosis of exclusion. The syndrome presents with hematuria (blood in the urine) and flank (a region of the lower back beneath the ribs and above the ilium) pain which can result from a number of causes. Nonglomerular causes of bleeding (e.g., urinary infection, tumor, or nephrolithiasis) must be excluded. Obstruction of the urinary tract should not be present, confirmed by at least two imaging procedures while pain is present. Diagnosis of loin pain-hematuria syndrome (LPHS) occurs when hematuria is present, recurrent or persistent pain is severe, and other causes of bleeding are excluded. Urine testing can be performed to detect microscopic levels of hematuria. Protein is also commonly found in the urine of patients with LPHS. Kidney biopsies are sometimes performed to look for evidence of glomerular hematuria, excess red blood cells in the kidney tubules, and to assess the width of the glomerular basement membrane. Hematuria (more than 5 red blood cells per high power field) should be present in virtually every urinalysis and is typically characterized by dysmorphic red cells. Recurrent or persistent severe pain for  six months or more, occurring in the costovertebral angles. Relation to chronic pelvic pain
LPHS has considerable overlap with chronic pelvic pain syndrome.