Many studies have been conducted on the essential services provided by pharmacists during the COVID-19 pandemic. Pharmacists were likely to play an important role during this pandemic in multiple aspects, such as providing drug information to health care providers [11,12], patient counseling [13] and alternative suggestion therapy [14]. This study highlights the experience of integrating clinical pharmacy within a COVID unit at the university hospital center.

The clinical pharmacist is presented as a complementary health professional in the management of these patients, allowing them to secure their care pathways. They played an extremely important role in ensuring patient safety during the coronavirus pandemic, according to Li et al [15].

In our institution, the clinical pharmacy team has been reorganized to provide drug management for patients infected or suspected of having COVID-19.

The first step in securing the management of patients with COVID-19 was the elaboration of charts by a multi-professional therapeutic group. This was implemented during the first wave. It is composed of (infectiologists, pharmacists, etc.) who develop practical help charts that constitute a reliable database for the management of COVID patients [9].

In our study, the patients were mainly elderly women with hypertension and diabetes, the results of our study are in line with the American study by Richardson et al, which included 5700 American patients, which identified the same comorbidities with higher rates (56.6%, 33.8% for hypertension and diabetes respectively) [4].

During this period, the main drug-related problems were related to general anti-infective agents for systemic use (ATC J) which accounted for 25% (16/63). These problems were also identified in a French study by Mabille C. et al [16]. This therapeutic category was the cornerstone of the treatment of suspected or confirmed respiratory co-infections. Indeed, antibiotics are often prescribed in overdose, especially in patients with impaired kidney function.

For ATC P “Antiparasitics, insecticides and repellents”, clinical pharmacists mainly participated in optimizing the appropriate use of hydroxychloroquine, particularly in cases of interaction with drugs that prolong the QT interval.

Due to the many drug interactions of hydroxychloroquine with certain drugs that cause QT prolongation, it was essential to control their use, especially since they were very often prescribed by doctors who were not accustomed to their use.

This appropriate use has been framed as follows:

- An electrocardiogram (ECG) is done systematically before the initiation of treatment and during treatment.

- Development of a prescribing aid in cases of kidney or liver failure.

- Vigilance when hydroxychloroquine is associated with other drugs that prolong QT interval (the association must be discussed with a senior)

- Management of adverse reactions to hydroxychloroquine

During this study period, problems related to antithrombotic agents (ATC B) represent 17% (11/63). These PIs were important because of the high risk of thromboembolic complications in patients with COVID-19. In the majority of cases, a dosing error was observed and the PIs led to a change in treatment [17].

Thus, some pharmaceutical interventions have focused on the switch from oral anticoagulants (direct oral anticoagulants (DOACs) or vitamin K antagonists (VKAs)) to curative heparin therapy: low molecular weight heparin (LMWH), unfractionated heparin (UFH) to avoid the risk instability and drug interactions with the different COVID-19 treatments, especially with hydroxychloroquine.

The panel states that continuation of prophylactic anticoagulation with a DOAC after hospital discharge should be proposed in COVID-19 patients with two or more risk factors for venous thromboembolic disease (VTE) [18].

Prescribing a DOAC instead of injectable LMWH avoids the need for nurses to travel to patients who are unable to self-inject [18].

In more than a quarter of cases, a dosing error in case of relay with a DOAC was observed at hospital discharge. The PIs led to a change in treatment dose.

In the same context of treatment with an anticoagulant, cases of adaptation of the dosage to the kidney function in case of overdose have been reported in patients with kidney failure.

For the ATC H (Systemic hormonal drugs), the clinical pharmacist was mainly involved in the optimization of the appropriate use of corticosteroids. The High Council of Public Health (HCSP) recommends the application of the RECOVERY protocol, i.e., 6 mg/day of dexamethasone for 10 days, and failing that, the use of methylprednisolone at a dose of 32 mg/day, or prednisone at a dose of 40 mg/day, or finally, as a last resort, hydrocortisone at a dose of 160 mg/day for 10 days, with a gradual decrease in dose over three or four days [19]

Indeed, corticosteroids are often over-prescribed or over-dosed, and most PIs have been recommended by reducing the dosage or adapting the frequency of intake, as is the case of dexamethasone which was prescribed at a dosage of 6 mg/day but in three doses instead of one, and also the duration of treatment.

Medical acceptance rate:
According to Renaudin et al [20], a PI is considered accepted when the prescriber changes the prescription in accordance with the PI within a period not exceeding 48 hours. In our study, this percentage was significant and amounted to 95%. This reflects the familiarity of the physicians in the unit with clinical pharmacy as they were working in medical units that already had a clinical pharmacist integrated into the care team.