Alpha blockers in the management of ureteric lithiasis: A meta-analysis

2022 Recommendations of the AFU Lithiasis Committee: Management of symptomatic urinary stones

The acute situation, caused by an obstructive stone, is defined by a renal colic that may be uncomplicated, complicated, or at risk in specific conditions. Its management may be medical or require interventional treatment by extracorporeal shockwave lithotripsy, endoscopic removal, or ureteroscopy. METHODOLOGY: These recommendations were developed using two methods, the Clinical Practice Recommendations (CPR) and the ADAPTE method, in function of whether the question was considered in the European Association of Urology (EAU) recommendations (https://uroweb.org/guidelines/urolithiasis) [EAU Guidelines on urolithiasis. 2022] and whether they could be adapted to the French context.

The modulation of ureteral smooth muscle contractile responses by α1- and α2-adrenoceptor activation

PURPOSE

This study was performed to investigate the influence of α-adrenoceptor subtypes upon ureteral smooth muscle contractile responses.

METHODS

Rat ureters were challenged in vitro with noradrenaline (NA), the α₁-adrenoceptor agonist phenylephrine (PE), and the α₂-adrenoceptor agonist clonidine (CLON). The influences of the agonists on the magnitude and frequency of acetylcholine (ACh)-stimulated phasic contractile responses were recorded.

RESULTS

The magnitude of the phasic contractile responses effected by ACh was not significantly influenced by the adrenoceptor agonists, but the frequency of the response was significantly enhanced by all three agonists (p < 0.05). Idazoxan and prazosin abolished the rise in frequency effected by CLON and PE, respectively, whereas both antagonists in combination were required to abolish the increase in frequency effected by NA.

CONCLUSIONS

It has been demonstrated that α₁- and α₂-adrenoceptors modulate the contractile function of rat ureteral smooth muscle by increasing the frequency, but not the magnitude, of phasic contractile responses. The enhancement of contractile function by NA is mediated by mechanisms dependent upon both α₁- and α₂-adrenoceptors.

On medical treatment for ureteral stone expulsion

There is evidence that α-adrenoceptor (α-AR) antagonists facilitate the passage of ureteric stones, but the mechanism behind this effect has not been established. If one accepts that it is the friction between a ureteral stone and the mucosa that hampers the passage of the stone, and that the passage traumatizes the mucosa, the aim of treatment must be to reduce this friction. Elevated pressure above an obstructing stone results in an increase in tension in the wall of the upper urinary tract, including the tension at stone level, which causes an increase in friction and ureteric colic. Reducing pressure, by low but adequate fluid intake, non-steroidal anti-inflammatory drugs (NSAIDs), or α-AR antagonists that reduce the friction and give pain relief, seems to be rational. When the stone is pressed downwards by a high pressure the mucosa forms a bar ahead of the stone. These factors reduce the ureteral lumen and hamper the passage of both urine and the stone. The swelling can be reduced by NSAIDs. Filling of the ureter ahead of the stone reduces the friction between the stone and the ureteral mucosa. Evacuation of the urine ahead of the stone by effective peristaltic activity increases this friction. α-AR antagonists that reduce peristalsis may therefore be used to reduce the friction and consequently allow the stones to pass more often and earlier. For very early stone expulsion, a combination of NSAIDs and α-AR antagonists may be useful. There is no evidence that spasm influences the passage of ureteral stones.

Outcome of uncomplicated ureteric calculi managed with medical expulsive therapy in the outpatient clinic of a urology unit in Sri Lanka

OBJECTIVE

Although medical expulsive therapy (MET) is shown to be effective for ureteric calculi, the optimum duration and the stone size suitable for MET are not well established yet. The objectives of the study were to determine the optimum duration and maximum stone size suitable for MET.

RESULTS

All patients with radiologically confirmed uncomplicated ureteric calculi treated with MET using tamsulosin over a period of 6 months in the outpatient setting were followed up. There were 213 patients. 165 were men. Mean age was 42 years. At presentation 42 stones were in upper ureter (19.7%), 51 in mid ureter (23.9%), 120 in lower ureter (56.3%). The majority (82.7%) of stones were less than 10 mm. Seven stones (3.3%) were over 15 mm. Ninety-two (43.2%) patients had spontaneous passage of stones within 6-weeks of MET. Another 38.9% passed the stone within the next 6-weeks. Thirty-eight patients (17.8%) required surgery. Uncomplicated ureteric stones up to 10 mm can be given a trial of MET using tamsulosin which can be extended up to 12-weeks with a success rate over 92%. This may have substantial clinical and fiscal benefits by reducing the number of interventional procedures especially in resource-poor settings.